SAFETY GUIDE
Radiation Protection in Radiotherapy
Radiation Protection Series Publication No. ?? Public Comment draft: 24 August 2007
Submissions should be forwarded by 26 October 2007 and addressed to: Mr Alan Melbourne Manager Standards Development and Committee Support Section ARPANSA 619 Lower Plenty Road Yallambie VIC 3085 Or by email to: secretariat@arpansa.gov.au (Electronic submissions are preferred) All submissions will be held in a register of submissions, and unless marked confidential, may be made public.
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Safety Guide Contents
1. Introduction .................................................................................... 5 1.1 1.2 1.3 1.4 1.5 1.6 2. 3. CITATION ........................................................................................................ 5 BACKGROUND .................................................................................................. 5 PURPOSE ......................................................................................................... 5 SCOPE ............................................................................................................. 5 STRUCTURE ..................................................................................................... 6 INTERPRETATION ............................................................................................. 6
Justification..................................................................................... 7 Responsibilities ............................................................................... 9 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 THE RESPONSIBLE PERSON .............................................................................. 9 MEDICAL PRACTITIONERS ...............................................................................12 RADIATION THERAPISTS..................................................................................13 PERSONS ADMINISTERING RADIATION.............................................................14 RADIATION SAFETY OFFICER (RSO) ................................................................ 17 RADIATION ONCOLOGY MEDICAL PHYSICIST (ROMP) .................................... 26 THE SUPPLIER ............................................................................................... 27 THE EQUIPMENT SERVICING AGENCY ............................................................. 28 GENERAL CONSIDERATIONS ........................................................................... 30 DESIGN AND OPERATIONAL CONSIDERATIONS ................................................ 30 CALIBRATION OF RADIOTHERAPY EQUIPMENT .................................................31 CLINICAL DOSIMETRY .....................................................................................31 QUALITY ASSURANCE ......................................................................................31
4.
Optimisation of Protection for Medical Exposures ......................... 30 4.1 4.2 4.3 4.4 4.5
5. 6.
Quality Assurance .......................................................................... 32 Radiation Incidents........................................................................ 35 6.1 MANAGEMENT OF A RADIATION INCIDENT ...................................................... 35 6.2 INCIDENT PREVENTION .................................................................................. 35
7.
Treatment Planning and Delivery................................................... 37 7.1 7.2 TREATMENT PLANNING ...................................................................................37 TREATMENT DELIVERY .................................................................................. 39
8. 9.
Radiation Protection in the Care of a Patient with Brachytherapy Sources In Situ................................................................................41 Radiation Protection in the Event of the Death of a Patient Undergoing Treatment with Brachytherapy Sources In Situ........... 47
10. Radiation Monitoring and Radiation Levels ................................... 48 11. Storage and Transport ................................................................... 49 11.1 STORAGE AND HANDLING .............................................................................. 49 11.2 TRANSPORT ................................................................................................... 50 12. Repairs and Maintenance............................................................... 52
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Annex A
RADIATION MANAGEMENT PLAN ........................................... 53
WORKING RULES ..................................................................................................... 53 EMERGENCY PROCEDURES ...................................................................................... 54
Annex B Annex C Annex D Annex E Annex F Annex G Annex H Annex I Annex J
PROCEDURES ..................................................................... 59 BRACHYTHERAPY SOURCES .................................................. 63 EQUIPMENT AND FACILITIES ................................................. 69 QUANTIFICATION OF ERROR AND MONITORING OF INCIDENTS IN THE DELIVERY OF THE RADIOTHERAPY TREATMENT PROCESS......71 RADIATION WARNING SIGNS AND NOTICES ............................. 74 PROCEDURE FOR WIPE TESTING A SEALED RADIOACTIVE SOURCE OR SOURCE HOUSING ............................................................ 76 SURVEY METERS..................................................................77 HEALTH EFFECTS OF IONIZING RADIATION AND STANDARDS FOR CONTROL OF EXPOSURE ........................................................ 78 ARPANSA RADIATION PROTECTION SERIES PUBLICATIONS ...... 81
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1.
1.1
Introduction
CITATION
This Safety Guide may be cited as the Safety Guide for Radiation Protection in Radiotherapy (2007).
1.2
BACKGROUND
This Safety Guide has been prepared as a supplement to the Code of Practice for Radiation Protection in the Medical Applications of Ionizing Radiation (2007) (hereafter called ‘the Code’). The information contained in this Safety Guide is intended to provide practice-specific guidance in radiotherapy on achieving the requirements set out in the Code. Radiotherapy is the branch of clinical medicine that uses ionizing radiation, either alone or in combination with other modalities, for the treatment of patients with malignancies or other diseases. It includes responsibility for the diagnosis, treatment, follow-up and supportive care of the cancer patient as an integral part of the multidisciplinary management of patients. The use of radiotherapy has overall societal benefit but the high radiation doses involved with therapeutic exposures have the potential to cause harm to those who benefit from the treatment, health care staff and members of the public if inadvertent radiation exposure occurs.
1.3
PURPOSE
Although the guidance offered in this Safety Guide is in itself not mandatory, it is recommended that the measures included in this Safety Guide should be implemented in the interests of reducing radiation exposure and risks. This Safety Guide provides information to assist the relevant persons to meet the requirements of the Code in the delivery of radiation therapy. It includes information on the following responsibilities and protective measures:
• • • •
the related roles of the members of the multidisciplinary team and delegations of responsibilities; appropriate procedures for optimising protection through careful treatment planning and delivery; detailed recommendations regarding quality assurance activities; and recommendations regarding documentation and relevant departmental protocols.
1.4
SCOPE
This Safety Guide applies to the following ionizing radiation exposures in radiotherapy:
•
the exposure of patients as part of their treatment;
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• • • • •
the exposure of individuals participating in research programs1; the occupational exposure of individuals; the exposure of health professionals other than those with training in the medical applications of ionizing radiation; the exposure of carers; and the exposure of members of the public arising from the use of medical radiation equipment and radioactive sources.
It covers sealed source brachytherapy and teletherapy (external beam radiotherapy using photons, electrons and charged or uncharged particles) but does not address radioactive source teletherapy since it is no longer in use in Australia. The definitions of brachytherapy and teletherapy are given in the Glossary.
1.5
STRUCTURE
This Safety Guide sets out information that should assist in achieving the levels of protection established in the Code. It does not form part of the material that would be adopted into regulatory frameworks by State, Territory or Commonwealth regulatory authorities.
1.6
INTERPRETATION
The meaning of terms defined in the Glossary to this Safety Guide is the same as the meaning defined in the Glossary to the Code. Material in the Annexes provides clarification and guidance on issues discussed in this Safety Guide.
1
Specific requirements for research participants are given in the Code of Practice for the Exposure of Humans to Ionizing Radiation for Research Purposes (2005), ARPANSA. Page 6 of 92
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2.
Justification
All therapeutic exposures to ionizing radiation should be subject to the principles of justification and optimisation. For doses received by a patient undergoing medical diagnosis or treatment, there are two levels of justification. Firstly, the practice involving exposure to radiation should be justified in principle. In this context, the continuing involvement of medical professional societies should be ensured, as matters of effective medical practice will be central to this judgement (IAEA 2002). Secondly, each procedure should be subject to a further, case-by-case justification by the prescribing practitioner (ICRP 1991). The decision to perform a radiotherapeutic procedure rests upon the professional judgement of the benefits that accrue to the total health of the patient, as opposed to any effects that might be caused by the ionizing radiation. The benefit will be the potential therapeutic effect of a procedure resulting from the medical exposure, including direct health benefits to an individual as well as the benefits to society. The detriment will be the potential deleterious effects of ionizing radiation. The objective of radiotherapy is to deliver a radiation dose to a selected target volume of an organ or tissue for the purpose of killing cells. Such therapy results in absorbed doses that are orders of magnitude greater than those encountered in diagnostic studies. The dose is usually delivered in more than one treatment fraction. The potential for complications with normal tissue is significant. Such effects will often be an unavoidable part of a properly justified procedure. Therefore, the justification for each procedure should be carefully considered (IAEA 2002). The justification process should also take into account the efficacy, benefits and risks of using alternative procedures, for example surgery or chemotherapy, either alone or in combination with radiotherapy (IAEA 2002). Also influencing this choice will be practitioner preference and expertise, and the availability of the alternative procedure. Special cases that warrant further justification include the medical exposure of the pregnant or potentially pregnant patient, as there is evidence to suggest that the embryo or fetus is more radiosensitive than the mature adult (Delongchamp et al. 1997, Doll and Wakeford 1997). Likewise, radiotherapy involving children under the age of 18 years requires a higher level of justification since children may be more susceptible to the induction of radiation induced cancers (ICRP 1991, Delongchamp et al. 1997) and they have a longer life expectancy during which manifestation of possible harmful effects of radiation may occur. Paediatric radiotherapy is best performed in experienced centres, linked to paediatric oncology groups providing access to internationally endorsed treatment protocols. Research that exposes humans to ionizing radiation should conform to the requirements published by ARPANSA in Radiation Protection Series (RPS) No. 8 (ARPANSA 2005), which requires that proposals for research involving ionizing radiation be submitted for approval to a properly constituted Human Research Ethics Committee, including details of the level of exposure and the reasons justifying its use. Radiotherapy clinical trials involve high radiation doses at levels which cause tissue effects, specifically destruction of the cancer with an acceptable level of radiation induced complications. The risk associated with the radiation exposure needs to be explained to the research participant. However, radiotherapy clinical
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trials differ from research involving diagnostic investigations in that the participant may receive some potential benefit from the trial.
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3.
Responsibilities
The delivery of radiotherapy requires a multi-disciplinary approach, with input from a number of professional groups, interacting with equipment and source manufacturers and suppliers, maintenance engineers, and the relevant regulatory authorities. All staff members have an individual and joint responsibility to ensure their contribution to safe practices and treatment delivery. Consideration needs to be given to occupational exposure, medical exposure and exposure of the general public.
3.1
THE RESPONSIBLE PERSON
The Responsible Person may be a natural person or a corporation, and in the context of the practice of radiotherapy may be the CEO of a hospital or clinic, or a director of medical services of the hospital or clinic. The Responsible Person has overall management and control of the radiotherapy facility. The Responsible Person’s radiation safety policy documentation should clearly demonstrate the commitment of senior management to restrict unnecessary or unintended radiation exposure during the use of radiotherapy equipment. It should include consideration of radiation protection for occupational and for medical exposures, and should clearly identify those designated with responsibility and the scope of their responsibility. The legal responsibility for adherence to the Code lies with the Responsible Person. Although some tasks may be delegated to others, such as the institution’s Radiation Safety Officer (RSO), the ultimate responsibility lies with the Responsible Person. Under the Code, the Responsible Person is required to ensure that a Radiation Management Plan for the control of radiation exposure is in place. This plan would normally be developed by the institution’s RSO and the Radiation Oncology Medical Physicist (ROMP) working closely with operators and practitioners, and would be expected to specifically include written procedures or protocols to address the following issues: • • • • • protection of employees, patients and members of the public; the correct identification of the patient prior to the radiotherapy treatment being performed; irradiation of pregnant or potentially pregnant patients with specific advice about how to minimise the chance of irradiating the embryo or fetus; concerns about the risks from ionizing radiation and how to explain them to patients, guardians and carers; the protection of individuals (carers), who voluntarily help in the care, support and comfort of patients undergoing all forms of radiotherapy. The Responsible Person should be able to demonstrate that the effective dose received by the carer is unlikely to exceed 5 mSv per year (IAEA 1996). Carers should be individuals who are not normally occupationally exposed (for example, relatives and friends over the age of eighteen, who are not pregnant). Nurses and support staff should only assist if a carer is not available; accidental, abnormal or unplanned exposures to radiation; and regulatory requirements.
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The responsibilities of the Responsible Person and the roles of the Radiation Oncologist, Radiation Therapist, RSO, ROMP, service engineer and any other qualified persons who may use the radiotherapy equipment or sources should be clearly defined and documented. Responsibilities and lines of communication between employees and external radiation workers (such as service engineer contractors) should also be clearly defined to ensure adequate radiation safe practices are satisfied. Guidelines for the preparation of a Radiation Management Plan are given in Annex A. In relation to radiotherapy equipment or sources, the Responsible Person will need to ensure that: • • • • • • the relevant regulatory authority is advised of the sale, transfer or disposal of the radiotherapy equipment or sources; any records required by the Code are kept and updated; the general radiotherapy procedures detailed in the Annexes of this Safety Guide are followed; a comprehensive clinical protocol and treatment policy document for the treatment facilities is readily available, followed and regularly updated; where an electronic approval system is in use, all users have, and continue to have, individual and secure passwords; the quality control procedures expected by the prescription are followed in the delivery of the treatment even though the prescribing practitioner may be remote from the treatment site for certain types of treatment; after the installation or modification of any radiotherapy equipment, a ROMP carries out initial dosimetry and acceptance tests to verify that the equipment conforms to the technical specifications of the manufacturer or supplier; a radiation survey is undertaken prior to initial use of radiotherapy equipment and sources to confirm the shielding meets the relevant requirements; following initial acceptance or a major modification, a second verification of the dose calibration by an independent ROMP using an independently calibrated dosimetry instrument is carried out to minimise the risk of errors in acceptance; following maintenance or repair work on radiotherapy equipment, the equipment is not returned to clinical use until the ROMP has:
• •
•
•
•
•
received and accepted as satisfactory a written report about the work from the equipment servicing agency who performed it; and undertaken the checks necessary to ensure satisfactory function of the equipment before it is returned to clinical use.
•
if the maintenance or repair work was such that the safe operation or dosimetric accuracy of the radiotherapy equipment might have been affected, the use of the equipment for radiotherapy is not permitted until the ROMP has:
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• • •
assessed whether any specific tests or measurements need to be made; determined that the equipment is operating satisfactorily; and provided a written recommendation to the Responsible Person that the equipment can be returned to clinical use.
a routine schedule for calibration, dosimetry and quality assurance tests is developed and implemented. all radioactive sources are:
• • •
handled in accordance with the requirements detailed in Annex B; stored in accordance with the requirements detailed in Annex C; stored with appropriate security; and
before a new brachytherapy source is commissioned or loaded, the source manufacturer’s test certificate is inspected by a ROMP; routine checks of the integrity of brachytherapy sources are conducted in accordance with the requirements for brachytherapy source contamination checks; the following functions are restricted to persons who are appropriately authorised by the relevant regulatory authority:
•
•
loading sealed radioactive sources into brachytherapy equipment (including remote afterloading brachytherapy equipment) or unloading sources from such equipment; loading sealed radioactive sources into their transport containers or unloading the sources from their containers; and arranging for the re-location or disposal of sealed radioactive sources; all dosimetry calibrations, clinical dosimetry data and methods of calculation for therapy equipment are re-confirmed at intervals of not more than three years; the measurements and checks carried out for the dosimetry reconfirmation are sufficiently comprehensive to detect any significant variations from the data in use; the physical data and the accuracy of imaging modalities used for anatomical information and for quantitative purposes in treatment planning computer systems are determined; and the routinely availability and use of in-vivo dosimetry (e.g. thermoluminescent dosimeters or diodes) for direct clinical measurements where applicable;
• •
the ROMP arranges:
•
•
•
•
documentation describing measurements and results that verify the system of treatment delivery is maintained (ICRP 2000); and any reportable incident is reported to the relevant regulatory authority.
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3.2
MEDICAL PRACTITIONERS
Radiotherapy may be administered only on the prescription of a medical practitioner. Approved in this context means holding qualifications acceptable to the relevant professional specialty and authorised by the relevant regulatory authority. The approved medical practitioner is assigned the primary task and obligation of ensuring overall patient protection and safety in the prescription of, and during the delivery of, the treatment (BSS No. 115 Appendix II, IAEA 1996). Prescription of radiotherapy is normally restricted to the following specialties: • • • external beam therapy: Radiation Oncologists, Dermatologists (superficial radiotherapy only); intra-operative photon or electron radiotherapy: Radiation Oncologists; and sealed source brachytherapy: Radiation Oncologists, Ophthalmologists (eye plaque treatment only), Dermatologists (superficial radiotherapy only).
However during treatment application, members of other medical specialties may operate with the prescribing doctor (e.g. urologists and gastroenterologists for relevant manual brachytherapy procedures; cardiologists for intravascular brachytherapy). The treatment prescription should be given in writing, stating as relevant the site to be treated, the total dose and number of fractions (giving an indication of fraction size), and the time frame for completion of treatment. The planned technique and the intent of treatment should be documented. An indication of concurrent chemotherapy may also usefully be appended. The Radiation Oncologist (or relevant medical specialist) should be satisfied that the planning and dosimetry processes will adequately achieve the aim of the treatment, in terms of coverage of the tumour volume, appropriate dose to the tumour and appropriate dose constraints to protect normal tissues. Signature and dating of the treatment plan should indicate approval sufficient for commencement of treatment. The responsibility for this process and for overseeing the treatment delivery rests with the Radiation Oncologist (or relevant medical specialist), and while he or she cannot monitor every part of the process, there should be adequate interaction through the process to allow the Radiation Oncologist or medical specialist to fulfil this responsibility. The Radiation Oncologist should ensure that records of the treatment are retained in line with the recommendations of the Royal Australian and New Zealand College of Radiologists (RANZCR 2005). In order to fulfil the medical obligations outlined in the Code, the presence of an authorised Radiation Oncologist or relevant medical specialist (or their medical practitioner deputy) during application and/or delivery of the radiotherapy to the patient is required (in the treatment room or at the equipment controls, as appropriate) for those types of radiotherapy where immediate medical issues (routine or emergency) may arise during the application of the treatment. For interstitial or intraluminal HDR brachytherapy, the Radiation Oncologist (or medical practitioner deputy trained in the relevant emergency procedures) needs to be present at the controls of the treatment room for the duration of the treatment. This is to ensure that medical assistance is immediately available to remove the source applicator from the patient in the event of an emergency where the source
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cannot be rewound from an in situ applicator. However, the Radiation Oncologist would not be required to attend for superficial or intracavitary HDR treatments. The Radiation Oncologist (or medical practitioner deputy) should deliver the treatment (or be present) during the application of intra-operative radiotherapy. The Radiation Oncologist or relevant medical specialist (or their medical practitioner deputy) should deliver the treatment (or be present) for manual brachytherapy (other than non-surgical plaque application), including intravascular brachytherapy. It is not typical for the presence of the Radiation Oncologist to be required during application of routine external beam therapy or remote afterloading LDR brachytherapy, as these treatments are normally administered by the Radiation Therapist (in the case of external beam therapy) or by the medical physicist and radiotherapy nurse (in the case of remote afterloading brachytherapy). The Radiation Oncologist should maintain currency by ensuring that he or she meets the requirements in training, certification and continued professional development as approved by the relevant professional body. They should hold current professional registration to practice the relevant medical specialty and authorisation granted by the relevant regulatory authority for the prescription of the therapeutic radiation modalities. Oversight of treatment will include definition of the target volume and critical normal structures, setting of constraints for normal tissue tolerance, approval of the treatment plan and evaluation of the therapeutic radiation exposure. The Radiation Oncologist will also take responsibility for the development and adoption of protocols defining treatment schedules, prescribed doses and doses to relevant organs and other relevant tissues.
3.3
• •
RADIATION THERAPISTS
calculate and document the relevant clinical dosimetry parameters for planning and treatment; participate in the development, approval, implementation and regular review of the quality control program, conforming to the standards endorsed by the appropriate professional bodies; adhere to the manufacturer’s operating manual and any additional safe practice procedures for operating the radiotherapy equipment that may be prepared by the ROMP; report any equipment malfunction to the ROMP; and undertake Continuing Professional Development to ensure that knowledge and skill base maintain currency.
In conjunction with other professional staff, the Radiation Therapist will typically:
•
• •
Radiation Therapists work in the multidisciplinary team contributing to patient care during the process of delivering a course of radiotherapy. An accredited Radiation Therapist will be experienced in all aspects of planning and delivery of radiation treatment, which includes megavoltage, orthovoltage, superficial and brachytherapy treatments. In doing so, the Radiation Therapist may operate a broad range of radiotherapy equipment including linear accelerators, kilovoltage X-ray units, CT scanners and brachytherapy afterloading units. Safe and accurate administration of
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radiation is a fundamental role of the Radiation Therapist, working where relevant with other members of the multidisciplinary team. Radiation Therapists undertake all aspects of the treatment planning process including simulation/CT simulation, stabilisation device manufacture and computer assisted planning. Close interaction with Radiation Oncologists and ROMPs should ensure that the most appropriate technique for delivering the dose prescription is employed, particularly in determining the appropriate treatment technique for more complex cases.
3.4
PERSONS ADMINISTERING RADIATION
Persons administering radiation under the auspices of the approved medical practitioner will usually be a qualified Radiation Therapist, although in some circumstances such as brachytherapy the ROMP will also be involved. Administration of radiotherapy covers the localising, planning, verification and treatment delivery procedures. Radiation Therapists should deliver radiation treatment as prescribed by the Radiation Oncologist according to the departmental protocols describing patient positioning and planning, machine operation and the use of accessories. The Radiation Therapist should maintain accurate documentation and complete records of all radiation treatments as specified by the protocols within the Radiation Oncology facility. In addition, the Radiation Therapist should manage a comprehensive quality assurance and quality improvement program for patient related treatment/planning activities, underpinning the safe and effective delivery of all radiation treatment activities. Radioactive plaque application for ophthalmology and dermatology (not involving surgery) may be administered by a Radiation Therapist and would not normally require the presence of an authorised medical specialist or of a ROMP or their deputies. The presence of a ROMP (or the physicist deputy) during application and/or delivery of the radiotherapy to the patient is required, in the treatment room or at the equipment controls as appropriate, for those types of radiotherapy where matters of calibration, dosimetry and potential emergencies might be involved during the procedure. The normal requirements for the presence of a ROMP or physicist deputy during treatment are: • • • external beam therapy: for particular non-standard treatments only; intra-operative photon or electron radiotherapy: for all treatments throughout the treatment; sealed source HDR brachytherapy: for all treatments throughout the treatment (the physicist has an integral role during treatment in relation to safety and emergency precautions); sealed source remote afterloading LDR brachytherapy: for all treatments during initiation of the treatment; and manual brachytherapy (other than eye plaque application): during application/insertion of all sources.
• •
A ROMP or the physicist’s deputy should be present during the application and/or delivery of the radiotherapy, when it involves calibration, dosimetry or when
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potential radiation emergencies may occur during the procedure. A medical physicist should be present during treatment involving: • • • non-standard external beam therapy; all intra-operative photon or electron radiotherapy that may occur in the operating theatre or, conversely, in the treatment room following surgery; all sealed source HDR brachytherapy throughout the surgical and treatment procedures (the physicist has an integral role during treatment in relation to safety and emergency precautions); the operation and treatment insertion of sealed source remote afterloading LDR brachytherapy (such as radioactive iodine-125 seed prostate implants); and the application or insertion of all sealed radioactive sources for manual brachytherapy (other than non-surgical plaque application). Specific examples are the surgical placement of plaques for orbital retinoblastoma, mould implants to superficial tumours or interstitial implants using radioactive iridium-192.
•
•
External radioactive plaque application for ophthalmology (not involving surgery) may be administered by a Radiation Therapist and would not normally require the presence of a medical physicist or deputy. A ROMP (or the physicist’s deputy) should be available to provide general supervision during the course of hospitalised LDR brachytherapy (such as gynaecological insertions, prostate implants and special applicators using caesium-137, iodine-125 and iridium-192), including confirming that sources intended for removal at the end of the treatment have been removed at the scheduled time. Equipment design and departmental protocols will support personnel involved in delivering radiation to do so safely and to meet the requirements of the Code. All teletherapy treatment units should be equipped with a computer controlled verification and record system (V&R) that automatically compares individual patient personal details and treatment settings for each field. The V&R system will also be able to compare the predetermined treatment setting recorded for an individual patient treatment with the actual treatment settings of each treatment. The treatment parameters should be input manually or, preferably, by electronic transfer directly from the simulator or planning computer into the V&R system by the planning Radiation Therapist. All parameters should then be checked independently by another Radiation Therapist before the treatment is delivered. The predetermined treatment parameters should be assigned with appropriate tolerances to allow for daily set-up inconsistency. Only a designated Radiation Therapist should have the authority to override the predetermined treatment verification settings, according to defined protocols if the actual settings exceed the tolerance values. All overridden parameters should be identified and recorded in the patient treatment record for possible future clinical audit.
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Simulation films or digitally reconstructed radiographs of a patient treatment plan should be made available to use as a standard for comparison with portal images of the patient obtained during the course of treatment. For patients receiving radical radiation treatment, there should be clearly defined protocols for the frequency of taking portal films or images from an electronic portal imaging device or equivalent. Additional portal images can be obtained more frequently on request if consistency of patient positioning is in doubt. There should be defined protocols to allow positional corrections. Minimum monitor units should be adopted to achieve the best quality of portal images to minimise unnecessary exposure to the patient. Whenever possible portal images should be included as part of the treatment field and monitor units exposure. Special care should be taken when there are complex or unusual treatment plans or when there is a change in procedures (IAEA 2000a), such as: • • • • • a change of supplier of radioactive material; a non-typical dose; an unusual target area; a treatment with the patient in an unusual position; or a complex treatment.
A double check by some form of direct measurement should be arranged for these cases and considered as an important safeguard against the occurrence of treatment errors (a defence in depth principle). A person who administers radiation to a patient for radiotherapy treatment will need to: • document details of the doses delivered including the tumour dose, the dose to the treatment site, the absorbed doses to clinically relevant organs or critical structures, how the dose was delivered and any other information requested in the prescription; and follow all requirements of the Responsible Person’s Radiation Management Plan that are applicable to that person.
•
External Beam Radiotherapy and Intra-operative Photon or Electron Radiotherapy: A person who administers radiation to a patient for radiotherapy treatment with external beam radiotherapy, or with intra-operative photon or electron radiotherapy will need to: • • make a written record describing the delivery of the prescribed radiotherapy treatment to the patient; and ensure that the written record includes the following details:
• • • •
date of treatment; treatment site and field size(s); total radiation dose at the reference point; number of fractions;
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radiation type and quality; and doses received by critical normal tissues.
Similarly, a person who administers radiation to a patient radiotherapy treatment with brachytherapy will need to: • • make a written record of the details of the sealed sources used on the patient; ensure that the written record includes the following details:
• • • •
the activity; the batch number and expiry date of the source; the date and time of application or administration of the source; for permanently implanted sealed sources, the anticipated time when the radiation hazard from the sources becomes acceptably low; for non-permanently implanted sealed sources, the anticipated time when the sources are to be removed; the site being treated; and the dose administered to the treatment site;
• • •
follow the appropriate procedures for brachytherapy treatment delivery; and follow relevant written procedures for superficial brachytherapy involving ophthalmologic applicators, dermatological applicators or moulds.
No person may use or operate any radiotherapy equipment unless they have received the training detailed in the Responsible Person’s Radiation Management Plan and unless they are: • • familiar with the Responsible Person’s defence in depth procedures on all major treatment parameters and monitor units; and aware that all treatment plans are required to be signed by an approved medical practitioner and a person the Responsible Person has approved to check treatment plans.
3.5
RADIATION SAFETY OFFICER (RSO)
The Responsible Person may decide to delegate certain duties to a person such as a Radiation Safety Officer (RSO). Delegating duties to an RSO does not, however, absolve the Responsible Person from their legal responsibility for ensuring that those duties are carried out. In some Australian jurisdictions, the appointment of an RSO is, in fact, mandatory following the issue of an authorisation by the relevant regulatory authority. Typically, an RSO will: • • have sufficient professional and/or technical training to perform the RSO duties as detailed in this Section; undertake the measurements, investigations and assessments, keep the records and perform any or all of the duties specified in this Section;
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•
have the necessary authorisation, equipment, procedures and employee cooperation to undertake the measurements, investigations and assessments, and keep the records required specified in this Section; and ensure that the Responsible Person is kept informed of the radiation safety status of the practice.
•
A radiotherapy RSO should be a ROMP who has had extensive radiation training and experience and who has senior management responsibilities. In some organisations the institution’s RSO may not necessarily be a ROMP nor have direct involvement with the radiotherapy facility. For example, the RSO of a hospital might be a senior medical physicist in the hospital’s medical physics group who is not directly involved with radiotherapy. In such cases, the institution’s RSO would still be expected to have an appreciation of the radiotherapy facilities and the delivery of the treatment, and would closely liaise with the facility’s ROMP to ensure the most appropriate management of radiation safe practice in radiotherapy. The aim is to provide suitable administrative support and guidance for the management and approval of radiation safety procedures by the Responsible Person. The ROMP, designated as the radiotherapy radiation safety expert, should also ensure that satisfactory quality assurance (QA) programs and quality control (QC) testing for radiation safe practices in radiotherapy are performed. The radiotherapy radiation safety expert (the designated ROMP) normally has overall responsibility for the maintenance of up-to-date records for all stocks and locations of radiotherapy equipment, arranging for the safe storage of radioactive substances and ensuring the safe disposal of any radioactive waste. The radiotherapy radiation safety expert should also ensure that all shielding, radiation safety devices, radiation protective equipment, radiation monitoring and radiation surveying devices are provided by the Responsible Person. This would include ensuring that these are installed or available, regularly tested and serviced, repaired and replaced when necessary. The institution’s RSO will, in collaboration with a ROMP, typically have the following responsibilities in relation to the therapeutic use of radiation-producing equipment and radioactive sources: • • • • • be responsible for the maintenance of occupational exposures on behalf of the Responsible Person; oversee radiotherapy safety programs with regard to radiological and radiotherapeutic safety; as directed by the Responsible Person, develop an institution radiation safety manual or Radiation Management Plan; report any radiation incident to the Responsible Person; monitor radiation safety education within the clinic and any hospital departments, theatres or wards associated with the application of radiotherapy; and hold responsibility for the safety and documentation of radioactive sources.
•
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The policies, plans and procedures relating to the control and monitoring of exposure will commonly be developed and implemented by the institution’s RSO in conjunction with the ROMP designated as the responsible radiotherapy radiation safety expert. The designated ROMP should take responsibility for developing the dosimetry procedures and radiotherapy radiation safety issues. This should include the preparation of a plan for dealing with incidents, and emergencies in conjunction with the institution’s RSO. The institution’s RSO should provide local approval and regular review, which should be subject to the requirements and auditing of the relevant regulatory authority. The ultimate responsibility for developing a Radiation Management Plan lies with the Responsible Person. Nevertheless, this task will usually be delegated to the institution’s RSO and the designated ROMP who has specific radiation safety expertise in radiotherapy. Education and Training Radiotherapy programs should be conducted with adequate numbers of appropriately qualified and trained personnel (including Radiation Oncologists, ROMPs, Radiation Therapists, and nursing and support staff). Resources should be made available to assist with ongoing training and continuing professional development for the staff, particularly with the introduction of new technologies or techniques. Where the person operating or otherwise dealing with radiotherapy equipment or radioactive sources is acting under the supervision of an authorised person, this may be general supervision, personal supervision2 or immediate personal supervision3 depending on the level of experience and qualification of the person under supervision. Protection and Monitoring The design of the facility and the provisions of the Radiation Management Plan will provide radiation protection for staff within the exposure limits required by the regulatory authorities. There will be some level of exposure of staff within these limits, and the provision of approved personal radiation monitoring devices supplied by an approved provider is required for occupationally exposed persons for the particular category of procedures undertaken. Detailed recommendations for monitoring of personnel are found in Section 10 of this Safety Guide. The following considerations should be reviewed with regard to design of teletherapy and brachytherapy facilities to ensure appropriate protection of patients, personnel and visitors. Shielding Design In designing a therapy treatment facility, the Responsible Person should be aware of their obligations to limit the dose to employees and members of the general public to
2
3
Personal supervision is the exercise of control over radiation safety with the person exercising such control being present on the premises of operation.
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that required by the relevant regulatory authority. The dose constraint of 0.3 mSv per annum, to be applied to areas occupied by members of the general public, was recommended in the National Radiological Protection Board (NRPB)’s publication Board Advice Following Publication of the 1990 Recommendations of ICRP (NRPB 1991). The NRPBs recommendation was subsequently adopted by The International Commission on Radiological Protection (ICRP), as ICRP Publication 81 (ICRP 1998). Prior to the start of radiotherapy building works, a ROMP or RSO (suitably experienced in radiotherapy shielding methods and approved by the relevant regulatory authority) will determine and document the radiation shielding specifications for all protective barriers. Different requirements apply to the quality of radiation protection and shielding in brachytherapy, depending on the rate of dose delivery. Dose rates in brachytherapy are defined using reference air kerma rate in Gy.m2.h-1. Dose rates are divided clinically into: • • • • High Dose Rate (HDR): greater than 12 Gy.h-1, where the individual treatment fraction is delivered in minutes. Medium Dose Rate (MDR): greater than 2 Gy.h-1 and less than 12 Gy.h-1. Low Dose Rate (LDR) (0.4-2.0 Gy.h-1), which usually utilises a permanent implant. Pulsed Dose Rate (PDR), where a high activity source is used with cyclic administration during the treatment fraction, so that the dose rate is similar to HDR during the active part of the cycle but mimics the LDR delivery rate over the total treatment fraction. The instantaneous dose rates are 1.0 to 3.0 Gy.h-1.
A ROMP, or an approved radiation safety expert experienced in radiotherapy shielding requirements, should calculate and specify the radiation shielding details for all rooms housing radiotherapy equipment. This will include the mobile shielding requirements for IORT. Full details of the parameters on which the shielding calculations are based should be documented in a report and provided to the Responsible Person at the time of the architect’s or builder’s early planning stage. The site ROMP should be involved throughout the planning and building stages to ensure that the building design and facilities satisfy radiation safety safe standards and practice. Room Design Features for Teletherapy and for Brachytherapy Using Remote Afterloading Devices Rooms designed for Teletherapy and Brachytherapy using remote afterloading devices should have visible and accessible emergency switches controlling the mains power to the therapy equipment to allow for emergency termination of a radiation exposure. These devices might be used, for example, to terminate a patient treatment: • • in the event of uncontrolled movement of the patient; in the event of a staff member being accidentally left in the treatment room after commencement of the treatment; or
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•
to access the patient urgently.
All staff members should be familiarised (by the appropriate line manager) with the positions of all ‘emergency off’ buttons before being allowed to operate the unit. The operator (usually the Radiation Therapist) needs to be able to observe the patient/couch area throughout the entire radiation exposure. Closed circuit TV monitoring of the patient from beside the control panel is the usual method of achieving this. There should be an intercom system to allow 2-way audible communication between the Radiation Therapist and the patient. Wherever possible, operating consoles should be placed outside the treatment room. Where a treatment room has operating controls within it, scattered radiation may still scatter off ceilings and walls exposing the operator behind the protective screen. It is strongly recommended that rooms where such a configuration is still used be redesigned. Engineering and physics personnel may wish to by-pass dosimetry interlocks when tuning the beam steering while attempting to diagnose operating faults of the treatment machine. Normal interlocks on linear accelerators, such as ‘under dose rate’, ‘flatness’ and ‘symmetry’, may trip when the beam parameters are outside the normal limits. Interlock by-pass would not involve a patient’s treatment or allow anyone to remain in the room during the exposure. Service and physics personnel should follow the manufacturer’s procedures when any interlock is by-passed to maintain safe standards of operation and to avoid damaging the equipment. These personnel should be thoroughly trained in the safe operation, design and technical aspects necessary for on-going repair and physics quality assurance and calibration. The ROMP should use manufacturer’s software to set up user groups with different areas of access to machine control, to ensure only those qualified to adjust linac parameters are able to do so. For clinical or laboratory areas where remote afterloading brachytherapy radioactive sources are prepared, sterilised and cleaned, the facilities and design should conform to (or provide an equivalent level of safety as) the relevant requirements for radiation laboratories using sealed sources detailed in the Australian Standards AS/NZS 2982.1:1997 (Standards Australia 1997) and AS 2243.4-1998 (Standards Australia 1998). The ROMP or the institution’s RSO should be consulted if the use of a brachytherapy treatment room for any other purpose is planned whilst the brachytherapy source(s) is in its shielded container(s). It may occasionally be required to move a brachytherapy device from one area to another. The ROMP should be consulted if this is proposed, to ensure that the dose limits for individuals and the shielding and design aspects comply with the requirements of the relevant regulatory authority. Registration, Documentation, Notification and Reporting The Responsible Person may delegate to the institution’s RSO the responsibilities of providing all necessary information to the relevant regulatory authority and obtaining the required authorisations from the relevant regulatory authority.
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Each device should have its own record log, which contains information on equipment malfunction, component replacement, service upgrade or any other modification. Each entry should contain information on: • • • • • • date; action; reason for action; person performing action; date and time of return to clinical use; and person authorising clinical use.
Normally the ROMP is designated as responsible for the technical QA of the therapy equipment and treatment planning equipment. The service engineer should record the summary of any repair and maintenance carried out on radiotherapy equipment in the user’s service record book, which will be kept in a readily accessible place near each item of radiotherapy equipment. See Annex D of this Safety Guide for information regarding the Brachytherapy Source Register. For certain procedures when a patient is transferred to a different institution or clinic, the Responsible Person or delegate should (in the interests of ensuring optimisation and continuity of treatment) ensure that all relevant records of the patient’s radiation treatment are provided to the new institution or clinic. Emergency Plans and Radiation Incidents Guidance on emergency plans and radiation incidents is provided in Section 6 of this Safety Guide. Clinical Protocols and Treatment Policies The Responsible Person has overall responsibility for ensuring that clinical protocols and treatment policies are written, followed and regularly updated. In practice it will be the medical practitioners, in collaboration with other staff members including ROMPs and Radiation Therapists, who undertake these functions. The protocols and policies should include both details for the radiotherapy prescription, and the required procedures for planning, verification, dose delivery and quality assurance activities. It may also be useful to include background information discussing the evidence that supports the protocol or procedure. Commissioning and Equipment Servicing Commissioning, Calibration and Compliance The calibration, dosimetry and quality assurance responsibilities will be delegated by the Responsible Person to a ROMP. The Codes of Practice or protocols for the dosimetric calibration of therapy equipment should be in accordance with those adopted (and reviewed from time to time) by the Australasian College of Physical
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Scientists and Engineers in Medicine (ACPSEM). Relevant national and international calibration protocols include the ACPSEM protocol (ACPSEM 1997), IAEA Technical Report Series No. 398 (IAEA 2000b), IAEA Technical Report Series No. 277 (IAEA 1997), and the IPEMB Code of Practice (IPEMB 1996). The ROMP should compare the equipment or source test data to the technical specifications certified by the manufacturer or supplier. More detailed physics data are generally required to be measured and documented during the subsequent commissioning stage following acceptance. The ROMP will typically: • carry out full acceptance testing of new or modified radiotherapy treatment planning or dosimetry equipment. Where non-standard equipment is used, the tests need to take due regard of protocols provided by the supplier and include a risk assessment; ensure that records of all acceptance tests and commissioning data are kept and are readily available for later referral; ensure that the equipment is clinically used only for modes of treatment applicability that have been tested and accepted for use, and that all operators are duly informed of the limited conditions of use; and confirm the basic physics data stored in the planning computer system and that doses calculated by the computer treatment planning system are correct to within the accepted limits of accuracy.
• •
•
In most circumstances there are national or international standards to satisfy when commissioning or calibrating radiotherapy equipment. With the emergence of new technology, some component parts of radiotherapy equipment do not yet have national or international guidelines. Manufacturers should supply to the ROMP a list of other sites with the same equipment installed, and the ROMP should consult with other physicists experienced with that equipment configuration. No radiotherapy treatment or planning equipment should be released for clinical use until the ROMP is satisfied that the equipment is satisfactorily operating, calibrated and safe to use. The ROMP should re-calibrate therapy equipment after initial commissioning and calibration, at least at the frequencies prescribed in the ACPSEM quality assurance protocol (ACPSEM 1997) and under the conditions prescribed in the ACPSEM protocol. This procedure will ensure that the equipment will undergo sufficient recommission tests to confirm that the previous standards of operation are still satisfactory and independently re-calibrated in accordance with the calibration protocol for that equipment (ACPSEM 1997). The maximum interval between radiation output calibration (measured under reference conditions and in accordance with the ACPSEM dosimetry protocol (ACPSEM 1997)) for all beam energies and types should not be greater than one year. The test frequencies and tolerances for ionizing radiation apparatus and treatment planning systems are based on Kutcher et al. (1994) and on Van Dyk et al. (1993). X-ray Apparatus 4.5 mm Cu HVL) Operating up to 400 kVp (or maximum
The following criteria should be considered for X-ray apparatus: • • design criteria for shielding; shielding assessment;
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• • • • • •
radiation warning signs; radiation treatment controls; room design features; commissioning; calibration; and maintenance.
Linear Accelerators The following criteria should be considered for a linear accelerator: • • • • • • • • design criteria for shielding; shielding assessment; radiation warning signs; radiation treatment controls; room design features; commissioning; calibration; and maintenance.
Recommissioning In addition to the initial acceptance and commissioning, the same test and measurement procedures should be followed whenever a major upgrade or overhaul of the equipment is undertaken. ‘Major’ would mean that the calibration or performance specification of the equipment might have changed sufficiently to warrant re-evaluation of the clinical suitability of the equipment or that the associated planning/treatment data need to be updated. Some examples of situations considered as major are as follows: • External beam radiotherapy: Critical situations to consider for X-ray tube equipment would be the replacement of the X-ray tube itself, repairs or modifications to the high voltage and current controls and timer. Damage to filters or applicators may require detailed measurement as well as inspection after repair. Similarly, maintenance of the gun, target, waveguide, microwave source, dosimetry control circuits, ion chamber, flattening filter/scatterer replacement, machine tuning, its light optics and mechanical bearing system all require a reassessment of the equipment’s calibration and accuracy of radiation delivery. A mini-commissioning procedure is necessary when the X-ray tube or linear accelerator waveguide is replaced affecting the dosimetry or major bearings are replaced affecting the mechanical alignment of beam delivery. • Intra-operative therapy:
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Commissioning of a linear accelerator for intra-operative therapy in the treatment room or a mobile small electron type accelerator in theatre should follow the same guidelines as described above. Remote afterloading brachytherapy: Remote afterloading brachytherapy devices require a modified commissioning procedure after each new replacement radioactive source is loaded. For example, the accuracy of source activity, positional accuracy and source integrity should be determined prior to use. Any maintenance of the mechanical or electrical controls would necessitate a similar range of essential tests. Manual brachytherapy: Apart from regular quality assurance tests and safe practice housekeeping, individual radioactive sources should be tested if there is any indication of physical damage or wear, particularly if there is a possibility of radioactive source leakage from its inert, sealed container. All physical data procured during the acceptance testing and commissioning should be appropriately documented and should be used as a reference baseline from which to monitor the performance of the radiotherapy equipment during subsequent quality control performance or operational tests. For brachytherapy, where such data exist, source activity may be measured by one of three methods as in the report on the Code of Practice for Brachytherapy Physics (Nath et al. 1997): • • direct traceability, when the source or transfer instrument (e.g. well chamber) is calibrated against a national standard; secondary traceability, when the source is calibrated by comparison with the same radionuclide and design that has a directly traceable calibration or by a transfer instrument that bears a directly traceable calibration; secondary traceability by statistical inference which is established, when a source is one of a group of sources of which a suitable random sample has direct or secondary traceability; or for sources that do not yet have a national standard, users should develop a constancy check calibrated against the vendor’s standard and use this consistency check to verify the source strength. Other options also exist (for example the interpolative free-air standard method), but a clear protocol should be clearly established before such sources are used clinically.
•
•
The measurement technique designed to check the source manufacturer details supplied with the source should take account of: • • any inaccuracy of measurements arising from the very high dose rate emitted from sealed radioactive sources; and positional errors that may occur between the sealed radioactive source(s) and the radiation instrument used for the calibration, keeping them to a minimum.
See also later in this Section for guidance on equipment servicing.
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Storage and Transport of Radioactive Sources Specific details regarding storage and transport of radioactive sources are given in Section 11 of the Safety Guide.
3.6
RADIATION ONCOLOGY MEDICAL PHYSICIST (ROMP)
The ROMP is an essential component of the design and delivery of radiotherapy treatments and will, for a radiotherapy practice, generally fulfil the role of the Qualified Expert specified in the Code. The calibration, dosimetry and quality assurance requirements are the specific responsibility of an accredited ROMP (BSS No. 115, Appendix II, IAEA 1996). The role of the ROMP will typically include the following components: • meeting the training, certification and continued professional development requirements as:
• •
endorsed by the relevant professional body; and approved by the relevant regulatory authority; of the manufacturer's performance specifications; and relevant standards;
•
ensuring that the equipment complies with all:
• •
Before submitting a request for authorisation of radiotherapy equipment by the relevant regulatory authority; • in the case of any non-compliance with manufacturer’s specifications or relevant standards, carrying out a risk assessment of the variation and record the findings4; assisting and advising the Responsible Person on commissioning, acceptance tests and calibration of the output of the treatment equipment and for ensuring that all physical data being used at the site are accurate and adequate. The calibration standard needs to be traceable to a national standards dosimetry laboratory; overseeing and assisting in the implementation of the quality assurance program; overseeing and assisting in the development, implementation and regular reviews of radiation safety procedures; ensuring that:
• • • •
•
• • •
all new calculation methods and planning data are correct and verified by measurement of a simulation; sufficient planning dosimetry data are available; adequate tuition, documentation and procedures are supplied for dose calculations; and guidance is given regarding measured margins of error to establish the physical parameters of treatment regimens;
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undertaking full safety assessments of equipment where there is no appropriate national or international standard for the equipment design and operation in accordance; providing training to other staff groups in radiation oncology physics and radiation safety; ensuring the radiation safety of patients, staff and the public; providing expert advice in the application of physics and dosimetry principles in non-standard treatments; and undertaking continuing professional development to ensure that knowledge and skill base maintain currency.
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ROMPs should be involved in activities such as the development, implementation, maintenance and quality control of the infrastructure (facilities, equipment and computer systems) and the implementation processes necessary for the provision of new radiation treatments. This requires a thorough understanding of the physical principles in the production, attenuation and shaping of photon and electron beams in particular. One of the most critical factors in modern radiotherapy is the accurate localisation of the isocentre of the treatment machine in relation to the target volume. The ROMP should fully understand methods of error analysis and ensure that the methods used for patient positioning and portal verification are appropriate. The ROMP works in close collaboration with the institution’s RSO. The RSO has responsibilities for the development, implementation and regular review of radiation safe practices during radiotherapy treatment or planning procedures. The ROMP will undertake the investigation of incidents as delegated by the Responsible Person, and ensure the development of corrective measures to prevent a recurrence of similar incidents. The ROMP will also submit a suitable report (where necessary) to the institution’s RSO, to the radiation safety committee for the hospital or practice and to relevant authorities.
3.7
THE SUPPLIER
The supplier of radiotherapy equipment should routinely incorporate current national standards in the design of their equipment, and when national standards are not defined, should ensure adherence to appropriate international standards. Accompanying documentation should make reference to which standards have been adopted, and record the stringency of adherence to those standards. Implicit in this is the assurance that the required levels of radiation protection are met, all safety controls are in full working order, and that there is redundancy within the system in case of failure of one component. When negotiating contracts with radiotherapy departments, the suppliers should demonstrate how their products fulfil the safety requirements of the purchaser and that the appropriate standards are reached, and work with the purchaser to show that the standards are achieved when the equipment is operational. Any deviation from the required standards should be resolved through mutual collaboration of both parties.
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Suppliers of radioactive sources have particular obligations, including the assurance of safe transportation until accepted by the purchaser. They should be fully conversant with the requirements in each jurisdiction, and be confident that any agent they employ during source transportation is also fully conversant with the regulations. The supplier also has ongoing obligations to the source purchasers. When the activity and half-life of a radioactive source makes it impractical to store for decay at the hospital or clinic site until sufficiently inactive, the suppliers should make arrangements to repossess the source for safe storage and disposal. This requirement should be included in the contract agreement between the supplier and the hospital or clinic. This typically applies for larger activities of nuclides with half-lives of months or years. Repossession arrangements by the supplier should apply when: • • • • iridium-192 sources are used for HDR brachytherapy (the supplier normally repossesses the old source when the new source is loaded); caesium-137 sources used for LDR remote afterloading have reached the end of their useful life due to low activity or poor source integrity; caesium-137 sources used with manual applicators have reached the end of their useful life due to low activity or poor source integrity; eye or skin plaques using strontium-90, cobalt-60, or ruthenium-106 when they have reached the end of their useful life due to low activity or poor source integrity; and strontium-90 intravascular brachytherapy sources have reached the end of their useful life due to low activity or poor source integrity. Phosphorus-32 intravascular brachytherapy sources, have a relatively short half-life of 14 days, but should normally be repossessed by the supplier.
•
Other sources with shorter half-lives (such as gold-198 and palladium-103 seeds) may be stored at the hospital or clinic until sufficiently decayed to be regarded as inactive and then disposed of in a suitable manner as a non-active source. All reference to indicate radioactivity on the source or container should be removed. Similarly, sources of small activity but with half-lives of months (such as iodine-125 seeds and iridium-192 wire) may be stored at the hospital or clinic until sufficiently decayed to be regarded as inactive and then disposed of in a suitable manner as a non-active source. All reference to indicate radioactivity on the source or container should be removed.
3.8
•
THE EQUIPMENT SERVICING AGENCY
meet the requirements in training, certification and continued professional development as endorsed by the relevant professional body and of any authorisation required by the relevant regulatory authority; be responsible for installing and/or maintaining equipment at the specifications given in the contract between the supplier and hospital/clinic or between the service firm and hospital/clinic, as relevant; ensure that a comprehensive set of manuals is available for all installed equipment; and
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Radiotherapy equipment service personnel should:
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•
undertake continuing professional development to ensure that knowledge and skill base maintain currency.
Equipment service personnel may be employed by the supplier of the equipment or by the organisation housing the equipment. The responsibility to conform to the protection requirements and procedures of the organisation remain the same in either instance. In addition to any formal qualification and training required by the relevant professional body, service personnel should attend such training courses as are offered by the manufacturers for new or upgraded equipment with which they are not familiar. The manufacturers will also notify all service personnel of equipment updates and field change orders. This applies equally if a contractor is involved in equipment maintenance.
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4.
4.1
Optimisation of Protection for Medical Exposures
GENERAL CONSIDERATIONS
Once clinically justified, each radiotherapeutic procedure should be performed so that the dose to the patient is the lowest necessary to achieve the desired therapeutic effect. Since patients may accrue direct benefits from medical exposures, it is not appropriate to impose strict limits on the doses received from fully justified procedures. In radiotherapy, it is necessary to differentiate between the dose to the target tissue and the dose to other parts of the body (ICRP 1996). If the dose to the target tissue is too small, the radiotherapy will be ineffective. The exposures will not have been justified and the optimisation of protection does not arise. The protection of tissues outside the target volume is an integral part of dose planning, which can be regarded as including the same aims as the optimisation of protection.
4.2
DESIGN AND OPERATIONAL CONSIDERATIONS
The degree of effects to tissue surrounding the target volume is a matter for Radiation Oncologists (or other approved medical practitioners) to evaluate (IAEA 2002). However, if the side effects differ significantly from the expectations of the clinician, this will be a matter of concern to the relevant regulatory authority. Furthermore, in the case of accidental overdoses there will be no opportunity to correct the mistake. Any unplanned or unexpected outcomes resulting from doses either higher or lower than intended should be reported to the relevant regulatory authority (see Section 6 of this Safety Guide). The Code highlights the need for individuals performing or directing exposures of ionizing radiation to take particular care when irradiating pregnant or potentially pregnant patients. The IAEA Basic Safety Standards (BSS), Safety Series No. 115 (IAEA 1996) requires the selection of the appropriate radiotherapy treatment considering complications with normal tissue and the possible detriment to any embryo or fetus that might be present when the patient is a woman who is or is likely to be pregnant. The patient should be informed of possible risks. Multiple safeguards (the defence in depth principle) for all critical components of radiotherapy equipment should be used, with the aim of preventing a single failure leading to serious consequences (IAEA 2002). Especially critical for safety in radiotherapy is the understanding of equipment displays and the accompanying operational and maintenance documents. If they are in foreign language, their written translation in to the local language and terminology should be prepared and should be accessible at any time to the operational staff. The timely replacement of brachytherapy sealed sources should be undertaken so that treatment times are kept reasonably short to ensure that the potential for movement of the patient is low.
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4.3
CALIBRATION OF RADIOTHERAPY EQUIPMENT
Guidance on the calibration of radiotherapy equipment is given in Section 3 and Annex B of this Safety Guide. To ensure accurate and safe clinical usage, calibration of radiotherapy equipment should be undertaken at commissioning, after source change and after major repairs or modifications that may affect dosimetry. The intervals for these calibrations may differ, depending on the type of source and unit. The miscalibration of radiotherapy equipment can result in inappropriate treatment involving many patients and can lead to serious consequences. The application of the defence in depth principle by means of redundancy and diversity will help to prevent miscalibration.
4.4
CLINICAL DOSIMETRY
Doses should be optimised consistent with obtaining the desired result from the treatment, and the risk of errors in the delivery of such doses should be maintained as low as reasonably achievable. Prescription, planning, dose delivery and documentation should follow nationally and internationally accepted terms and concepts. Phantom and in vivo measurements should be performed as part of clinical dosimetry. Treatment planning systems are an essential component of treatment delivery and therefore full documentation of the commissioning and validation processes for these systems should be available.
4.5
QUALITY ASSURANCE
Guidance on Quality Assurance is given in Section 5 of this Safety Guide. The Code requires the establishment of a comprehensive Quality Assurance program with participation of appropriate qualified experts in the relevant fields. The Quality Assurance program should be regularly reviewed and updated. The Quality Assurance program should be linked to institution’s Radiation Management Plan in order to strengthen safety while at the same time improving quality and efficiency.
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5.
Quality Assurance
An effective quality assurance program involves all activities in the delivery of radiotherapy from clinical practice itself, through to administration and physical and technical aspects. The aim of the Quality Assurance program is to ensure that all procedures are appropriately defined, documented, understood, put into practice, and regularly reviewed. In the multidisciplinary radiotherapy environment, no one professional group has expertise in all areas. Development and oversight of the program may be facilitated by the establishment of a Quality Assurance Committee (QAC), composed of representatives from the relevant professional groups. The QAC should meet on a regular basis to review the program and oversee its implementation. The QAC should assign clear-cut lines of responsibility for all therapy employees to ensure adequate radiation protection of patients, workers and the public. A well-defined reporting structure should be put in place for review of faults and errors, easily accessible for all staff. The QA program should cover all aspects of care delivery, but of particular importance is the responsibility for all aspects of equipment QA. The QAC should oversee the quality assurance program for which the ROMP is responsible, focussing on radiotherapy equipment maintenance, servicing, dosimetry, radiation safety, and software release and testing. Monitoring by a ROMP should ensure that regular constancy tests, dosimetry and preventative maintenance services of radiotherapy equipment are performed at appropriate intervals. The director in charge of a radiotherapy facility has the responsibility for ensuring the availability and implementation of a comprehensive clinical protocol program or treatment policies, and that they are regularly reviewed and updated. The aim is to ensure safe practice and to allow non-standard approaches to be reviewed prior to introduction into practice. It is the responsibility of the prescribing medical practitioner to carefully assess all conditions relative to the patient with malignant or benign disease before the decision to treat is initiated. Quality Assurance Program The intent of QA is to ensure the delivery of treatment in a consistent and accurate fashion, realising the treating Radiation Oncologists’ clinical intent and ensuring maximal radiation protection to the patient and any person otherwise exposed during the delivery of the treatment. Because of variation between sites and equipment options, each QA protocol will be designed from first principles by the ROMP to reflect the particular environment it is designed for. Basic aspects include: • • • • safety of the patient, the public and the institution; positional accuracy; temporal accuracy; and dose delivery accuracy.
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Reference to the ACPSEM QA protocol (ACPSEM 1997) will assist the ROMP in arranging an appropriate QA program to ensure satisfactory accuracy of treatment. The Quality Assurance program for linear accelerators should be designed to ensure that: • • they comply with the accepted tolerances listed in the ACPSEM QA protocol (ACPSEM 1997); they are tested and calibrated at regular intervals in accordance with accepted protocol for linear accelerators at frequencies listed in the ACPSEM QA protocol (ACPSEM 1997) and in accordance with the ACPSEM dosimetry protocol; the following specific tests are carried out at intervals of not greater than fourteen days:
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•
photon and electron output constancy checks with a field instrument using temperature and pressure corrections; backup monitor constancy; light/radiation field coincidence; field size indicator (collimator setting); cross-hair centring; and gantry and collimator angle indicator; the leakage radiation (excluding neutrons) measured at a distance of 1 metre from the axis of the accelerating waveguide, does not exceed 0.5% of the ambient dose equivalent rate measured on the central axis of the beam at the normal treatment distance; adjustable beam limiting devices for photons attenuate the radiation in the area shielded by them such that the ambient dose equivalent rate at the normal treatment distance does not exceed 4% of the absorbed dose on the beam axis at the same distance; and adjustable or interchangeable beam-limiting devices for electrons attenuate the radiation in the area shielded by the devices to the extent that the absorbed dose at the normal treatment distance does not exceed: • 2% of the central axis absorbed dose, averaged over the area bounded by the line 40 mm outside the 50% dose contour and the maximum field size; and 10% of the central axis absorbed dose, at any point in the area bounded by the line 20 mm outside the 50% dose contour and the maximum field size.
•
radiation leakage is within required limits:
•
•
•
•
The Quality Assurance program for kilovoltage units (up to 400 kVp or maximum 4.5 mm Cu HVL) should be designed to ensure that: • the apparatus:
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complies with accepted tolerances for kilovoltage X-ray apparatus listed in the ACPSEM QA protocol (ACPSEM 1997) for kilovoltage X-ray equipment; and is tested and calibrated at regular intervals in accordance with the accepted protocol for kilovoltage X-ray equipment frequencies listed in the ACPSEM QA protocol (ACPSEM 1997) and in accordance with the ACPSEM dosimetry protocol for kilovoltage X-ray equipment; physics field dosimeter checks of X-ray output constancy is not greater than one month; the output calibrations, measured under reference conditions, are not greater than one year; and the half value layer (HVL) checks are not greater than one year;
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specific maximum QA frequencies for the interval between:
• • •
radiation leakage produces an ambient dose equivalent rate as indicated for each energy (ACPSEM 1997). The measurements should be made under the following conditions:
•
for apparatus operating in the range of 1 – 8mm Al HVL: • • • • • • 1 metre from the focal spot; averaged over any area of 100 cm2; no principal linear dimension exceeds 20 cm; the nominal X-ray tube voltage; and an X-ray output loading for the maximum specified energy input in one hour; an ambient dose equivalent rate not exceeding 1.0 mSv in one hour; 1 metre from the focal spot; averaged over any area of 100 cm2; no principal linear dimension exceeds 20 cm; the nominal X-ray tube voltage; and an X-ray output loading for the maximum specified energy input in one hour; an ambient dose equivalent rate not exceeding 10 mSv in one hour; and
•
for apparatus operating in the range of 0.4 – 4mm Cu HVL: • • • • • •
X-ray transmission through the diaphragms and the sides of applicators does not exceed 2% of the useful beam.
The ROMP, in arranging an appropriate QA program for brachytherapy, should take into account the design and operation of the brachytherapy device (refer to ACPSEM QA protocol (ACPSEM 1997)) to ensure satisfactory accuracy of treatment. The computer program should be checked for accuracy in dose calculation after every modification or upgrade. The calibration of any new source should be checked and the correct activity used for calculation.
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6.
6.1
Radiation Incidents
MANAGEMENT OF A RADIATION INCIDENT
Two groups of radiation incidents occur. Radiation emergencies arise, for example, when a remote-controlled brachytherapy source fails to return to the safe or the failure of a fail-safe mechanism designed to terminate an external beam treatment, or when a patient suffers a medical emergency during treatment with brachytherapy. Departments will need to develop generic emergency plans that can cover all possibilities and ensure that all staff members are thoroughly educated in the procedures to follow. The aim in education on types of potential incidents and rehearsal of appropriate responses is to ensure that all parties are able to act promptly to minimise the radiation risks arising from the emergency. All staff should be thoroughly versed on types of potential incidents, and rehearsed in the appropriate responses to minimize the radiation risks arising from an emergency. The procedures to deal with an incident should include, as relevant: • • • immediate action to reduce exposure; action to prevent non-essential access; and action to prevent dispersion of radioactive substances.
Radiation incidents other than emergencies may arise because of errors in treatment delivery. Annex E discusses the different levels of errors or incidents that may occur in delivery of the prescribed radiotherapy dose to the patient, and the obligations of staff in such events. By convention (ICRU 1993, ICRU 1999), the acceptable dose variation permitted across a target volume is limited to +7% to –5% of the prescribed dose. When errors in treatment planning or delivery occur that have an effect on dose that is less than 5%, these should be recorded but are not considered clinically significant. Dose variations greater than 10% require formal reporting to the relevant regulatory authorities. Errors of dose between 5% and 10% are not likely to have serious clinical consequences but require appropriate investigation of cause and identification of the means by which to minimise the risk of their repetition.
6.2
INCIDENT PREVENTION
Operators of radiotherapy facilities need to take all reasonably practicable steps to prevent incidents, such as (although not limited to) those described above. The following factors are recognised as important components of any program devised to address this requirement: • • • • • structural organisation; education and training; acceptance testing and commissioning; quality assurance programs; multiple levels of independent checks (redundancy); follow-up of equipment faults; repair and maintenance programs; communication and transfer of essential information;
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awareness and attention to procedures and protocols; patient and site identification; external beam radiotherapy – beam calibration, treatment planning systems, treatment simulation, set-up and delivery; brachytherapy – source ordering, delivery, calibration, and acceptance, source preparation, source removal; unsecured long-term storage or abandonment of radiotherapy sources; and public exposure and environmental contamination.
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7.
7.1
Treatment Planning and Delivery
TREATMENT PLANNING
Treatment Prescription As a minimum, the treatment prescription should include the following: • • • • • the treatment site; the total radiation dose; the number of fractions and the overall treatment time; the prescribed point dose and the radiation type and quality; and dose constraints for critical normal tissues.
For radionuclide therapy, the symbol of the nuclide with its atomic number should be clearly defined as part of the radiation treatment prescription. The radionuclide and its administered activity should be clearly shown, and countersigned by ROMP (or their deputy) responsible for isotope measurement. Treatment Planning - Brachytherapy The planning process incorporates source placement and activity to calculate accurately the time required for the source to remain in position in and around the target volume. This can be achieved by manual or computerised planning methods. Manual planning is a useful way of checking the accuracy of computerised planning, but is being used less and less frequently. It should be avoided whenever possible for clinical use. Methods for manual planning include: • • • • Manchester system; Paris system; Quimby system; and Memorial monographs.
Computerised planning of brachytherapy implants should be used as the ideal form of planning process. Different vendors supply programs based on different dose calculation techniques; the ROMP should be included in the decision to obtain and use such software. In addition to pre-planning, dose evaluation should be carried out after the permanent implantation of a radioactive source. This is the assessment of the quality of the procedure to ensure that the required dose was delivered to the target area. This can be by simple estimation for single line source insertions, but most commonly requires replanning with repeat capture of anatomical data (as with perineal implantation of prostates with permanent seed sources). See Annex C for further information regarding brachytherapy sources.
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Treatment Planning – External Beam Teletherapy using linear accelerators offers clinically superior beam characteristics and an inherently greater radiation safety profile than did the former use of sealed radioactive source teletherapy. There should be a well-defined and documented pathway for each patient treatment process, with each stage showing: • • • • • action required; expected time for stage; staff group responsible; independent check process and method; and action to be taken if any changes required.
Each stage of treatment planning should be clearly documented and initialled by the staff undertaking the treatment planning procedures, checked and countersigned by a second person. Use of CT scans (acquired under treatment conditions), as the basis for treatment planning, should be standard for all radical and high-dose palliative treatments. Additional information from other CT, MR and PET scans should be used whenever appropriate to the target volume definition. For treatment monitor units (MU) calculation, the MUs can be initiated manually or by utilising a computer calculation program. The computer calculation program used should undergo commissioning and testing as with any type of equipment before it is introduced into clinical use. Both manual and computer calculation procedures require an independent check to ensure they are free of errors. Any changes to the original treatment plan (e.g. due to change in patient thickness) should be subjected to the same checking requirements as an initial calculation. The patient’s treatment record should have the following information: • • the patient’s personal details for identification purposes; treatment details including regions of the body being treated, quality of radiation used, the magnitude of radiation dose and treatment parameters such as treatment site, total dose, beam type and energy, fractionation, limited dose to organs of risk, treatment position, set up details and treatment technique employed; and the consent of the patient to receive the radiation treatment signed by both the patient and the treating Radiation Oncologist.
•
Before computer treatment planning equipment is introduced clinically, it will need to be tested to ensure that the: • computed dose distributions for all of the external radiotherapy beams intended to be used, compared with measured data, are within acceptable tolerances; computed dose distributions for all the available brachytherapy sources are within tolerances of published or measured data; and
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critical data input and output devices are operating correctly.
A standard set of beam profiles and depth dose measurements will therefore need to be generated by the computer treatment planning program and compared with measured reference data. The computer treatment planning equipment will need to be retested when the radiotherapy equipment to be used is different from that with which the system had been tested. Where the planning computer software is changed or upgraded, standard computer generated plans for a comprehensive range of treatment techniques should be compared with: • • • previous plans; manually calculated plans; or directly simulated phantom dosimetry measurements.
Any discrepancy between dosimetry plans will need to be resolved before the clinical use of the equipment. Patient Immobilisation The type of immobilisation method to be used during external beam radiotherapy should be predetermined before any planning process begins to ensure consistency of patient positioning between treatment planning and delivery. The manufacture of fabricated immobilisation devices such as facemasks or customised polyurethane moulds should be performed by adequately trained mould room staff to ensure the devices can be fitted accurately for later planning and treatment procedures. Target Localisation and Simulation Patients should in general undergo X-ray simulation or CT scanning in the treatment position to enable localisation of the volume to be treated. In certain circumstances it may be preferable to define the target volume using surface markings. The target volume should be delineated by the treating Radiation Oncologist, according to the criteria outlined in ICRU Report 62 (ICRU 1999). The treatment target, organs at risk and potential organ movement should be taken into account when computing the treatment plan. Corrections should be made for well-defined tissue inhomogeneities that will cause significant dose variation. Computer Planning Computer planning of a standard technique should be performed by an experienced Radiation Therapist. Complex and non-standard treatment techniques should be planned with advice as required from an experienced ROMP, fully trained with the software. Whenever possible, a conformal beam approach should always be employed when selecting the treatment technique in order to minimise adverse side effects.
7.2
TREATMENT DELIVERY
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Clinical staff including Radiation Oncologists, Radiation Therapists and nurses should collaborate to develop protocols for assessment of treatment progress (including port films and other quality assurance issues), review of patients through their treatment course and the management of acute side effects. Collaboration with other staff groups involved in the delivery of multi-modal care should also be sought.
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8.
Radiation Protection in the Care of a Patient with Brachytherapy Sources In Situ
Usual practices of informed consent to treatment should be followed before undertaking brachytherapy. If an operative procedure is required, permission should be given in writing before it is commenced. Once the prescription is written and verified, the source containers are positioned, the sources checked, and the treatment can commence. Two trained staff should enter the treatment area, identify that they are treating the correct patient, connect the appropriate equipment, cross check that all connections are in place and correct, and load the programming information into the computer. The doors to the suite are closed, with alarms set in case of accidental interruption. Parameters such as radioactive source activity, time of treatment and the applicator source positions (where applicable) will be independently checked by a second trained staff member and confirmed on the treatment documentation with their signature and date before the commencement of the treatment. With the exception of procedures such as the application of beta-ray applicators a ROMP, RSO, or an authorised responsible officer, will be present at the time of initiation of a procedure to assist with the monitoring, accounting of sources, checking the surrounding area when the procedure has been completed and ensuring that radiation safety procedures are appropriate. Low dose rate brachytherapy may be performed manually or with a remote afterloading unit. Where remote afterloading offers an equivalent technique, application of treatment using remote afterloading apparatus is strongly recommended rather than manual application. While a patient is undergoing treatment as an outpatient to the hospital or clinic he or she should be isolated so long as sources are in situ, kept under observation and any movement of the patient should be restricted within the premises pending discharge. Brachytherapy Emergency Protocols All departments offering brachytherapy will need a local emergency procedure document (including, where appropriate, surgical procedures) that it is made readily available for staff to read or refer to and is located at the control unit outside the treatment room. The procedures should be simply and clearly documented, and detail the position of the suitably shielded container and remote handling tool(s) within the treatment room for use in a source emergency procedure. Any incident deviating from the planned dose delivery should be managed as an emergency and the appropriate procedure followed, including investigation of the cause of the incident. In the case of an emergency, the primary consideration is for the safety of the patient. Before the patient is administered a radioactive implant into a patient, the administering person should query the patient as to whether the patient is involved with close care of a child.
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After a Brachytherapy Treatment At the end of treatment (or at any time, if not required) all sources will be returned to secure housing. In the case of manual afterloading, the Radiation Oncologist should ensure this step; in the case of automatic afterloading, the equipment will automatically return the source to the safe. In either case, the ROMP will routinely and manually check the immediate environment with a suitable radiation monitor to check that there is no chance that the source has been left unintentionally in the patient, or in the room, but not in its correct housing. When a loaded appliance is removed from a patient it should be inspected immediately in case a part has become detached. The patient should then be monitored with a suitable radiation monitor to ensure all sources have been removed. Any prepared sources that are not used for treatment should be promptly returned to the safe and recorded by the custodian. At the end of treatment all temporary sources should be removed from the patient, returned to the safe and recorded by the custodian. The patient and treatment room should be monitored at the end of each procedure to ensure that all sealed sources are accounted for. Any sealed source that is dislodged or removed prematurely from a patient will also require immediate return to safe housing, and the incident recorded. The matter should be reported as soon as possible to the medical practitioner in charge of the treatment or appointed deputy and the ROMP or RSO. Radiation Protection in a Ward Caring for a Patient with Brachytherapy Sources In Situ In some hospitals and clinics the supervision of the ward radiation safety issues of brachytherapy inpatients may be performed by the ROMP who has been involved with the administration of the brachytherapy sources. In other hospitals and clinics the responsibility for ward radiation safety issues may be passed to the institution’s RSO in lieu of a ROMP. The general principles of radiation protection should be followed, that is, to minimise the period of time in contact with, and the proximity to the patient. An assessment of external dose-rate from a patient undergoing treatment with radioactive sources to nearby occupied areas will be made by the ROMP or RSO to minimise exposure of other patients and staff. The maximum allowable contact times should be calculated by the ROMP for each patient/radionuclide, and displayed at the entrance to the patient’s room. Consideration should be given to the relative merits of using a single room with solid walls between the patient and occupied areas, and distancing from these areas. Consideration also takes into account the possible exposure of patients or staff located in adjoining rooms and on the floors above and below. The estimates of dose levels in adjacent areas for the various types of treatments should be confirmed by dose rate surveys performed by the institution’s RSO, ROMP or deputy. If it is impossible to use a single room, the bed occupied by a patient being treated with radioactive sources should be located in a less frequented part of the ward, with solid walls between the patient and occupied areas; a mobile barrier should be used to shield the rest of the ward. When two or more patients are being treated, beds should be grouped together rather than be distributed throughout a ward. A patient
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with sealed sources in situ should have their bathing and toilet arrangements clearly defined. A clear indication should be posted at the room entrance that sealed radioactive sources are present. The radiation warning sign on the door5 to the patient’s room should have an additional instruction such as ‘Visitors must contact the Ward Sisterin-Charge before entering’, any special conditions or conditions should be listed and contact numbers of the institution’s RSO, ROMP or deputy should be displayed. The bed of a patient undergoing treatment should also be marked with a warning sign indicating the presence of a radioactive source in the patient. A shielded emergency container should be provided for the storage of dislodged sources, and should be able to be securely fastened, preferably lockable. If it becomes necessary to use it for dislodged sources, it should be marked with the contents when the sources have been transferred to it, and the Ward Sister-in-Charge, the Radiotherapy RSO and the responsible medical specialist should be informed as soon as possible. All dressings, bed linen and bedpans from a patient with sealed sources in situ should be checked before disposal in order to guard against loss of sources. This check will be made by a suitably trained person using a radiation monitor. Specific instructions written by the RSO covering action to be taken in the event of suspected loss of a sealed source will be kept in the ward where the patient is located. These instructions should cover the following: • • • immediate action to prevent movement of any related material such as bed linen, bed pans, clothing and so on; notification of the loss or suspected loss to the institution’s RSO for the purpose of supervising the search procedures; and follow-up reporting of the incident and its outcome.
In the event of a medical emergency to the patient or physical emergency on the ward, the patient’s medical management takes priority. However, attention to the radiation safety of staff should be incorporated as far as practicable and there should be arrangements for line of communication of safety precautions in these instances. Staffing As part of their responsibilities the ROMP and/or institution’s RSO should provide suitable radiation safety tuition for all staff involved with caring for patients with indwelling sealed sources. Nursing staff need to be familiar with the precautions to be undertaken for patients undergoing treatment, including safety requirements for domestic staff and visitors, and the nature and duration of the hazard. Protocols to deal with unexpected interruptions should be readily available for staff as part of the brachytherapy documentation. In attending patients, staff should work at the maximum practical distance from sources of radiation, and for as short a time as possible. If remotely operated afterloading sources are used, they should be withdrawn from the patient during these periods and re-inserted afterwards. Mobile shields of adequate lead equivalence and size near the bed can often be of value in reducing radiation
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exposure and should be used whenever practicable, but the advice of the ROMP or RSO should be sought in this regard. Nursing staff should be instructed to wear a personal dose meter, and depending on the radionuclide, to work using appropriate lead shields. Nursing staff who are, or think they might be, pregnant should not be involved in the care of patients with sealed radionuclides. In certain circumstances (such as when frequent nursing care is required) it may be desirable to use a roster system of duties in order to reduce individual doses, but this should not be a substitute for good radiation protection practices. Visitors to Patients The time that visitors spend in the close vicinity of patients who have in situ brachytherapy sources that produce penetrating radiation should generally be restricted and visitors should be encouraged to maintain the maximum practicable distance from the patient. In general, women of reproductive capacity and children under 16 years of age should not be permitted to visit patients undergoing treatment, but, where their visiting is permitted, adherence to time and distance constraints is mandatory. Where the treatment involves sources that produce penetrating radiation, it is desirable for the patient to be given a designated private room situated as remotely as possible from areas that may be occupied for substantial periods of time by other persons. Barrier shielding of the brachytherapy patient’s bed or structural shielding of walls around the treatment room may have to be provided if dose levels to adjacent areas are not reduced sufficiently by distance and integral shielding of the building structure. Dose rates to floors above and below should be considered as well as the adjacent rooms on the same level, with occupancy factors for these areas taken into account. Movement of the Patient within the Hospital or Clinic If a patient is to leave the ward during brachytherapy treatment, the following procedures should be adopted: • • • the ROMP or the institution’s RSO or their delegate is to be informed and their instructions followed; the person in charge of the department to receive the patient is to be informed of the movement and of the hazard; the patient should be escorted by a staff member competent to ensure that any radiation risk or risk of contamination presented by the patient's activities outside the ward is minimised; where a risk of loss or dislodgement of a sealed source occurs, checks will be made when the patient leaves and re-enters the ward to ensure that the sealed source complement or array is intact; any trolley or wheelchair moving a patient with gamma emitting sources in situ will display a sign indicating the presence of radioactive sources, and be moved so that the sources are as far from the attendant as practicable;
•
•
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• •
when the movement of a patient necessitates the use of a lift, an exclusive lift should be used; and the patient wears a wristband that states:
• • • • •
patient name; type of treatment, including the word ‘radioactive’ (e.g. ‘radioactive eye applicator treatment’); radioactive trefoil sign; radionuclide, activity, date treatment commenced; and emergency contact details (treatment doctor and/or physicist).
Discharge of a Patient Undergoing Brachytherapy The recommendations and principles contained in ARPANSA Radiation Protection Series (RPS) No. 4 (ARPANSA 2002b) should be noted. In general, patients with temporary sealed implants or moulds will not be discharged without removal of the source(s). In certain circumstances it may be permissible for a patient to be treated at home or as an out-patient with a surface source; in such settings the principles of protection as described in the section above will also be followed. With specific regard to the discharge of a patient with a permanent sealed source implant, the responsible medical practitioner and the RSO will provide the patient with written details of the implant source(s) and activity, and written and verbal instructions regarding radiation protection. These will apply particularly to travel on public transport, and the avoidance of members of the public, with special reference to contact with women who are pregnant and children. It is also recommended that the patient be provided with the means of retrieval and storage of dislodged sources, to be returned to the RSO for disposal. Information should also be supplied to the patient’s general practitioner including details of procedures to be followed in the event of unexpected death. When the patient lives in a remote area and sealed sources are to be removed by him or her, detailed written instructions for the removal, storage and return of the sources should be given to the patient and/or a guardian. For the storage and return of the sources, the following procedures should be adopted: • upon removal of the sources at the specified time, the sources or loaded appliances are to be placed in a strong container which is suitably identified. The container should be provided by the hospital or clinic; any identification worn by the patient should be removed at the same time as the sources and placed in the container; the container should be securely locked and then stored away from occupied space in some inaccessible position so that children cannot obtain it. It should be left in that position for a specified period, which should be not less than one month. Care should be taken that the container is not placed near undeveloped photographic materials; and
• •
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•
after the specified period, the container and its contents should be returned, as instructed, to the hospital or clinic.
The medical responsibility for a decision to allow a patient with sealed sources in situ to leave the hospital or clinic lies with the medical practitioner in charge of the treatment or an appointed deputy. The radiation protection responsibility for such a decision lies with the ROMP and ultimately the RSO in accordance with the requirements of the relevant regulatory authority. However, for long-lived sealed sources such as caesium-137 or iridium-192 no discharge will be allowed. A patient undergoing treatment with sealed sources will be advised, for such time as radiation safety precautions apply, to wear or carry identification on their person, giving the name and activity of the radioisotope and the date of application. If the patient is to be discharged whilst still undergoing treatment with sources, the name and telephone number of the physician to be called in an emergency is to be included. Written instructions on relevant radiation safety precautions (including any restriction of time in confined public places) and the date until which these instructions apply, will be provided to the patient and/or family and relevant patient carers. The information should also be included in the inpatient medical record. There should be additional instruction notes as relevant for the patient, family and general practitioner on discharge. The patient’s daily circumstances should be such that effective doses to members of the public and to adult persons who care for the patient are unlikely to exceed the dose limits and constraints given in ARPANSA/NOHSC Recommendations and National Standard, RPS 1 (ARPANSA 2002a/NOHSC 2002). If the patient is to return home where there are women who are pregnant or young children, clear instructions regarding the possible radiation risks to them will be supplied in writing. Procedures to avoid secondary radiation exposure of a child under close care A patient who has received a radioactive implant, and who is involved with close care of a child, should be provided with advice relating to the external radiation dose on:
(a) (b)
the length of time for which he or she can hold, or be in close proximity to, the child; and the date or time after which no restrictions will be necessary.
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9.
Radiation Protection in the Event of the Death of a Patient Undergoing Treatment with Brachytherapy Sources In Situ
As detailed in Section 8 of this Safety Guide for the discharge of a patient, information on the relevant date to which radiation safety precautions apply should be prepared by the ROMP or institution’s RSO and included in the medical notes of the inpatient. This information facilitates the notification to the RSO at the treating hospital or clinic in the event that the patient dies with the sealed radioactive sources in situ. The notification will normally be given by the ward staff in the case of an inpatient or by the patient’s family, patient’s doctor, or funeral personnel in the case of a discharged patient. If the deceased patient has a temporary implant/applicator in situ (ie designed to be removed after a preset treatment time), it is appropriate that the sources be removed by an authorised person as soon as possible. If the deceased patient has sealed sources in situ as a permanent implant, it may be appropriate to excise the implant tissue before release of the body to the mortuary or funeral personnel. The necessity for this will depend on the type of radiation (penetrating or non-penetrating), the amount of remaining activity, the site of the implant and the proposed extent of handling of the body (post-mortem, embalming, etc), and the intentions for disposal of the body (cremation, burial or entombment). Appropriate physics advice may be needed to ensure the safe disposal of the body. The aim should be to avoid unnecessary exposure of post-mortem or embalming personnel if the implant cannot be readily shielded, and to prevent cremation should the activity significantly exceed the exemption levels given in the IAEA International Basic Safety Standards (BSS), Safety Series No. 115 (IAEA 1996). Permanently implanted sources are not normally an impediment to burial.
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10. Radiation Monitoring and Radiation Levels
As a minimum, it is recommended that all persons operating or otherwise dealing with radiotherapy equipment or radioactive sources for radiotherapy purposes should be monitored with personal radiation monitors (such as film, TLD or OSL dosimeters) unless it can be shown that the exposure is controlled by integral shielding with an effective dose below 1 mSv per year. The monitors should be worn on the trunk, under any protective apron where applicable. The monitors should be changed at regular intervals, and the appropriate monitoring period should be determined by the type of radiation and the type of procedures being carried out. Where the exposure is from behind fixed structural shielding (such as for Linac or normal HDR operation), a monitoring period such as 3 months is generally satisfactory. Where the exposure involves operator skill to keep doses as low as possible (e.g. with manual brachytherapy or source handling), a shorter monitoring period such as a month is recommended. In some cases, personal direct-reading electronic dosimeters may be deemed appropriate in addition to, or instead of, the personal radiation badges (for example, for use by ward nurses instead of the badges, or immediately available for emergency use in facilities such as HDR brachytherapy in addition to the badges). For some brachytherapy and source handling procedures, periodic finger dose monitoring may be appropriate.
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11.
11.1
Storage and Transport
STORAGE AND HANDLING
Security for radioactive sources includes physical security, warning signs that include the contact details of the RSO or other representative of the Responsible Person (for the benefit of emergency personnel), and tracking of movement of sources. The Code requires that the Responsible Person in whose name the brachytherapy sources are held keeps a register of the sealed sources. The sealed Source Register should track all movement of the sources so that they can be accounted for at all times. The custodian who keeps the sealed Source Register on behalf of the Responsible Person could be, for example, a ROMP. In keeping this register the following details should be included: • • • • • • • written authority for issuing the sources required; name of the medical practitioner requiring the sources; name and location of the patient for whom the sources are required; identification and activity of each source issued and the total number and activity of the sources issued; name and signature of the person receiving the sources and the date and time of issue; date(s) of expected return of sealed sources; and date(s) and time(s) of actual return of sealed sources and the signature of the custodian on receipt of the sources.
The Responsible Person should provide the local fire service with details of the location of any sealed source safe or store, and instructions in the event of a fire. Regular and timely examination of a selection of the most commonly used brachytherapy transfer tubes, catheters, applicators, connectors, adaptors and any other equipment through which a brachytherapy source directly passes will ensure early detection of any contamination, and should be part of all brachytherapy quality assurance programs. Brachytherapy sources often have small internal diameters so that it may not be possible to wipe test inside the source container, although a wipe test should be performed wherever possible. Procedures for wipe testing are given in Annex G. When a wipe test is not possible, tests should be made to detect radiation emitted by any radioactive contamination inside or on the outer surface of the source transfer system or applicator. Significant contamination of remote afterloading brachytherapy equipment is unlikely but is confirmed if the results of the contamination check indicate an activity of more than 20 Bq from the wipe test, or radiation greater than twice normal background from the check with the sensitive radiation detector.
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Advice to the relevant regulatory authority of significant contamination of remote afterloading brachytherapy equipment and sources is necessary in order that relevant information is disseminated to other sites using similar equipment.
11.2
TRANSPORT
The consignor’s responsibilities for the safe transport of radioactive sources between sites lies with the Responsible Person. The Responsible Person will, however, most likely delegate the task to the RSO, or to a transporter authorised by the relevant regulatory authority. In either case, the Responsible Person will need to ensure that, before dispatch, the sources are packaged for transport according to the requirements of the Transport Code6 and to any further requirements of the relevant regulatory authority. Before dispatch of the sources, the Responsible Person should ascertain the transport route, means of transport and the responsibility for each stage of the journey. There should be close liaison between Responsible Person, supplier and any transporter to ensure that the transport route, means of transport and responsibility for each stage of the journey is clearly defined. This will ensure that all appropriate documentation is completed and received, that the timing of shipment is known and acceptable, that the transport method and route are confirmed, and that individual responsibilities are understood. Relevant points for consideration include: • • • • • the need for special handling equipment for sealed sources, during transfer from one mode of transport to another, or between vehicles; checking of radiation dose rates from the package or container; checking the correct transport labels are attached to the package or container, and replacing any that are damaged or illegible; ensuring that the package or container is securely attached to the vehicle and that the vehicle is correctly labelled; and security of the consignment during transport, particularly during delays or overnight stops.
Preparations to ensure safe transportation should include confirmation of the integrity of the packaging, the absence of contamination, attachment of appropriate and legible warning labels and completion of a transport document. The required information may be found in the Transport Code, and should include information regarding the type of nuclide and number, activity and construction of sources, relevant specific approvals and details of any special arrangements required. Some radioactive sources may be returned to the supplier at the end of their working life. The Responsible Person may take responsibility through the RSO for return of these sources or pass this responsibility back to the supplier at the time of source change. The Responsible Person or supplier, as relevant for the dispatch, ensures that the sources are packaged for transport according to the requirements of the Transport Code and to any further requirements of the relevant regulatory authority. The Responsible Person or supplier, as relevant, may engage the services of a carrier authorised by the relevant regulatory authority for the transport.
6
The Code of Practice for the Safe Transport of Radioactive Material 2001 published by the Chief Executive Officer of ARPANSA in September 2001. Page 50 of 92
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When returning empty packages to the Supplier, the Responsible Person should follow similar procedures in liaising with the supplier to confirm responsibility, route, modality and date of transport. The package should be examined to ensure its good condition, tested for residual contamination, have all warning labels removed and replaced by a label stating ‘UN 2908 RADIOACTIVE MATERIAL EXCEPTED PACKAGE — EMPTY PACKAGING’, and relevant transport documentation should be completed. The Responsible Person will normally be responsible from dispatch until the consignment reaches the consignee’s premises. Other arrangements are satisfactory provided they are agreed in advance by both parties and are also acceptable to the regulatory authorities. Although the supplier is normally responsible for the packing and transport of radioactive sources by mutual agreement, the Responsible Person should immediately report to the relevant regulatory authority any breach of the transport requirements of that authority.
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12. Repairs and Maintenance
Local procedures should ensure clear lines of communication between service engineers, the ROMP and the Radiation Therapist. Defined procedures for taking a machine out of, and returning it to, clinical use should be developed and clearly understood by the relevant staff. In situations where the ROMP cannot be contacted at the completion of the service work, then the site should ensure a local protocol is documented and made available such that out-of-hours service reports or records are transferred to the in-house medical physics and engineering services and entered as part of the equipment service history. The ROMP would then authorise that the therapy equipment is returned to clinical use. There should be a clear sign or record book to show which staff group or individual is responsible for the equipment at any time. This responsibility extends to radiation safety of all staff; reporting of incidents or malfunctions; returning the equipment to safe working order at the end of the session.
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Annex A
RADIATION MANAGEMENT PLAN
It is a requirement of the Code that the Radiation Management Plan be reviewed and updated at appropriate intervals. The Radiation Management Plan should be viewed as a living document such that as changes occur to equipment, operators or work practices, it should be reviewed or updated to reflect the changing nature of the use of radiation at the practice. The Code requires that work practices be included in the Radiation Management Plan. Work practices will include working rules that need to be followed to ensure a high standard of radiation safety and procedures that need to be followed in the event of an incident or emergency. In addition to general incident or emergency procedures, some specific scenarios should be considered, e.g. fire, flood, loss of control of source(s), or unintended radiation exposure to persons.
WORKING RULES
Working rules should be clear and easy-to-understand and should include details of: • • the expected radiation levels around the radiotherapy equipment and sources; arrangements for personal monitoring including:
• • • • •
the personal monitoring equipment servicing agency; type of personal monitor to be worn; wearing position; requirements for storage of personal monitors when not in use; and the storage location of the control monitor;
• • • • • • • •
arrangements for preventing or minimising radiation exposure of operators and members of the public; steps to be taken in the event of an emergency; particular practices to prevent relevant foreseeable incidents; any authorisation requirements and conditions of each relevant regulatory authority in whose jurisdiction the radiotherapy equipment or sources will be used; arrangements for the implementation of any special instructions from or requirements of the relevant regulatory authority; arrangements for the safe calibration, repair and maintenance of the radiotherapy equipment and sources; instructions concerning the posting of radiation warning signs (see Annex F) when the radiotherapy equipment or sources are in use; and relevant contact addresses and telephone numbers including:
• • • •
the institution’s RSO; where relevant, the maintenance agency; personal monitoring equipment servicing agency; and relevant regulatory authority, as well as the after hours emergency number.
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EMERGENCY PROCEDURES
Written emergency procedures for inclusion in the Radiation Management Plan should include the following items: • • instructions on the immediate actions that need to be taken to protect human life, limit injury and provide first aid where required; instructions on the immediate procedures needed to bring the incident under control, including details on the action necessary to:
• • • •
prevent the further spread of contamination (if this possibility arises); prevent unauthorised and unnecessary access to the secured area; provide or augment shielding against external radiation; and allay panic;
• •
instructions for the operator involved to report the incident to the institution’s RSO or the Responsible Person; instructions for the institution’s RSO to:
• • • •
assess the nature and scope of any radiation hazard; implement any further action required to bring the incident under control; immediately report the incident to the Responsible Person, and to the relevant regulatory authority; investigate the circumstances of the incident and undertake assessments, measurements and calculations, in order to determine the optimum corrective action plan and to estimate the doses of the operators and members of the public involved in the incident; assemble the necessary resources and implement the required corrective action, taking into account any instructions from the Responsible Person and the relevant regulatory authority; prepare a detailed report of the incident as soon as possible after the incident and submit this report, within seven days of the incident, to the relevant regulatory authority, through the Responsible Person; and advise the Responsible Person and the relevant regulatory authority on changes required to prevent the recurrence of a similar incident;
•
•
•
•
names, addresses and telephone numbers required in the event of an emergency (these should be checked and updated at least once every 12 months and when changes in arrangements are made); any other instructions to cover possible emergencies, such as:
• • • • •
•
observed or suspected damage to radiotherapy equipment or a radioactive source, e.g. displacement from a moving vehicle, crushing by a vehicle etc.; observed or suspected malfunction of the radiotherapy equipment; suspected or actual loss of radiotherapy equipment or source(s); failure of safety procedures or a breach of the working rules; and fire, flood, explosion or other disaster or incident in relation to the radiotherapy equipment or sources.
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MANAGEMENT OF AN IN-PATIENT BRACHYTHERAPY MANAGEMENT PLAN
When an in-patient is undergoing treatment with sealed radioactive sources in situ, the Responsible Person should: • provide a designated bed or room for the brachytherapy patient such that the distance and any intervening barrier shielding adjacent occupied areas will ensure that doses to members of the public (including other patients) or to persons occupationally exposed will not exceed the relevant dose limits; ensure radiation warning signs with the radiation trefoil and words such as ‘Patient undergoing treatment with radioactive sources’ are displayed on the patient’s bed and on the entrance to the patient’s room; ensure the patient wears a wrist band which displays the radiation trefoil and which states the:
• • • • • • •
•
•
patient’s name, type of treatment (including the word ‘radioactive’), radiation trefoil, radionuclide, source activity, date of commencement of treatment, and radiation emergency contact details;
• • •
ensure that appropriate radiation safety instructions are provided to all staff caring for the patient (including, where relevant, protocols for radiation emergencies); ensure staff confirm that remote after-loaded sources are fully withdrawn before attending to the patient; ensure that when staff are required to attend to a patient with sources in situ where there are significant dose rates, mobile bed shields of adequate lead equivalence and size are provided next to the patient; where relevant, ensure that special procedures are clearly described for the patient’s toiletry arrangements when sealed sources are in situ and may possibly be dislodged during treatment; ensure that to avoid the loss of dislodged sources, a suitably trained person routinely checks with a radiation monitor all dressings, bed linen, bed pans and relevant effects from the patient, before disposal or removal of these items; ensure a shielded container and appropriate handling tongs for dealing with potentially dislodged sources is available close to the patient’s bed for temporary storage of a dislodged source; and ensure instructions on the restriction (time and/or distance) on visitors, especially women who are pregnant and children, are provided to ensure that dose limits will not exceed the relevant dose constraint.
•
•
•
•
Where an in-patient with brachytherapy sources in situ is moved within the premises or between different premises that patient should retain any identification wristband. Further, the patient should be accompanied by staff trained in relevant radiation safety and emergency procedures. Any instructions provided by a ROMP or the RSO need to be adhered to by all persons attending to the patient and all sources accounted for and appropriately recorded at the commencement and end of the patient transfer.
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Before an in-patient undergoing brachytherapy is discharged, the medical practitioner making the medical decision to discharge the patient will need to ensure that all caesium-137 or iridium-192 sources have been removed before the patient is discharged. Where the patient is undergoing treatment with radioactive sources other than caesium-137 or iridium-192, the opinion of a ROMP or RSO will need to be sought regarding when the radiation levels are safe for discharge of the patient. The patient will need to be issued with sufficient radiation safety instructions, prepared by a ROMP or RSO, to provide adequate radiation protection of the public. These should include directions that the patient carries the information on his/her person detailing: • • • • the name and activity of the radionuclide; the date of its application; the name and telephone number of the medical practitioner, the ROMP and the RSO to be called in an emergency; and the date on which the requirement may cease.
Guidance about when a patient may be discharged from hospital is provided in the ARPANSA Recommendations for the Discharge of Patients Undergoing Treatment with Radioactive Substances (ARPANSA 2002b).
SURVEY METERS
A suitable radiation survey meter that meets the requirements of Annex H should be readily available or accessible7 to monitor radiation emitted by the source.
STORAGE OF RADIOACTIVE SOURCES
Each radioactive source used for radiotherapy will need to be safely and securely stored when it is not in use and should be subject to the following requirements: • • • When in storage, each source should be placed securely into the shielded position; Each source should be placed in a store for radioactive materials and not be stored with explosives, or combustible, corrosive or oxidising chemicals; and A permanent record of the fact that the radioactive source is stored, or has been issued, should be kept by the Responsible Person.
The store for radioactive sources should be constructed of durable materials capable of physically securing the radioactive sources. It should be designed and constructed so that the radiation levels outside the store: • • • do not result in an ambient dose equivalent rate or directional dose equivalent rate, as appropriate, that exceeds 10 µSv h-1; are as low as reasonably achievable in occupied areas; and are such that no member of the public can receive a dose exceeding 1 mSv per year;
When radioactive sources are in the store, the store should be labelled with a conspicuous sign8, the letters and symbol of which should always be black on yellow background, bearing the radiation hazard warning symbol and the warning ‘Store for Radioactive Materials’ or
7
8
‘Readily available or accessible’ means that the person can obtain a survey meter within a reasonable time. This may be achieved by borrowing, hiring or sharing a survey meter. Details of how the availability or accessibility of the survey meter are to be achieved are to be included in the Radiation Management Plan. An example of a suitable sign is given in Annex B of this Safety Guide. Page 56 of 92
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similar. It should be kept locked, with the ROMP having responsibility for the key, and have additional security measures put in place if required by the relevant regulatory authority.
TRANSPORT OF RADIOACTIVE SOURCES
Radiation placards, as required by the Transport Code, need to be displayed on a vehicle transporting a radioactive source even when there are other compatible dangerous goods present. ‘Mixed class’ placards cannot be used in place of the standard radiation placard. In the event of an incident during transport, the person in charge of the vehicle, or a person who is otherwise charged with the care of the radioactive source during transport, should immediately notify the Responsible Person for the source and the relevant regulatory authority.
EQUIPMENT INVENTORY
The Responsible Person should keep and maintain information records relating to the radiotherapy equipment or radioactive sources and update the inventory list following: • • • • a major upgrade; a radioactive source change; equipment replacement, decommissioning or removal; or the installation of new or updated software.
The following records should be kept for the operational life of radiotherapy equipment: • • • • • • • • equipment specifications; records of equipment acceptance tests; commissioning records; calibration records; quality assurance records; records of routine maintenance9; records of repairs or maintenance work; and records of the equipment’s downtime.
Records for each radioactive source should detail: • • • • • • the date the radioactive source was received; the whereabouts and identification details of each radioactive source; the type of radioactive source; the activity and date of measurement of the activity of the radioactive source; if the radioactive source is incorporated in a sealed source apparatus, the identification details of the apparatus; and if the radioactive source was disposed of, the date of disposal.
Where sealed sources are used for brachytherapy, the brachytherapy Source Register and inventory should be reviewed on a six monthly basis.
9
Work intended by the manufacturer of the radiation source to be performed by the Responsible Person.
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An annual audit of all radiation sources should be carried out to confirm that there is no variation in the expected inventory and that the safety and security arrangements for the radioactive sources are still appropriate for the type of source.
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Annex B
BRACHYTHERAPY PROCEDURES
Design, maintenance, and quality assurance standards for radiotherapy require careful and appropriate training and licensing of all personnel who use and maintain this class of equipment. Maintenance and quality assurance checks need to be in place to permit regular and consistent monitoring to ensure that the equipment is operating within accepted levels of performance. Sufficient safety measures should also be in place to permit a defence in depth strategy, to protect against incidents occurring in patient treatment or any other radiation incident involving staff or the public. GENERAL PROTECTION CONSIDERATIONS Standard procedures (ICRU 1985, 1993, 1997, 1999, and 2004) and quality assurance (QA) processes should be applied for all radiation modalities during the planning and treatment delivery processes, including equipment selection, commissioning, and maintenance, and staff requirements. BRACHYTHERAPY CONTAMINATION CHECKS Routine checks for integrity of the source, and for surface radioactive contamination of the source or associated equipment, should be performed with a minimum frequency of: • • • • • high dose rate brachytherapy sources: each time before the source is replaced, or annually when in continuous use; plaques: annually; low dose rate brachytherapy sources: annually; manual afterloading tubes: annually; and eye/skin applicators: annually.
Contamination checks should be carried out by a ROMP who is competent in operating the brachytherapy equipment or manipulating the source (as relevant) and in interpreting the contamination test results. Where the results of the contamination testing of afterloading brachytherapy equipment remote control equipment indicate the presence of significant contamination from the source, persons using the equipment will need to: • • • cease using it immediately; arrange for appropriate shielding to be applied to render the site safe for personnel, as appropriate; arrange for the appropriately trained and authorised personnel to review the equipment and identify and correct the problem and/or replace the source, as appropriate; arrange thorough decontamination of the equipment before resumption of use; and report the incident to the relevant regulatory authority.
• •
If the results of the contamination testing of manual afterloading tubes or of plaques indicate the presence of significant contamination, the affected tubes or plaques will need to be withdrawn from use.
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If the results of the contamination testing of applicators into which radioactive seeds have been loaded indicate the presence of significant contamination, the applicators will need to be thoroughly decontaminated before resumption of use. CALIBRATION OF RADIOTHERAPY EQUIPMENT All aspects of dosimetric calibration, including ensuring that all absolute dosimetry measurements are recorded, should be performed by or under supervision of a ROMP and, once the measurements have been completed, the records given to the Responsible Person. All radiotherapy equipment should undergo sufficient recommission tests at regular intervals to confirm the previous standards of operation are still satisfactory and be independently re-calibrated in accordance with the calibration protocol for that equipment (ACPSEM 1997). BRACHYTHERAPY SOURCE HANDLING Sealed sources with half-lives greater than 1 year should be tested at least once each year to confirm uniform distribution, and to identify any radioactive material leakage or surface contamination. Any sources found to be unsatisfactory will need to be immediately removed from service, sealed in an appropriately labelled suitable container, and stored. Details of the sealed source(s), activities, date of activity measurement and source numbers (identification e.g. serial numbers) should be clearly attached to the outer case of brachytherapy apparatus containing sealed sources. All movements of sources within the premises should be supervised, including to and from the radioactive source safe or store. When a radioactive source is transported within premises, it should be placed in a suitably shielded container and carried in a way that minimises exposure to radiation and that is secured to prevent tampering or theft. Each container should be labelled with a radiation trefoil, the name of the nuclide, its activity and date of measurement. All sources prepared or used for treatment should be returned promptly to the radioactive source safe or store when no longer in clinical use. BRACHYTHERAPY: SOURCE CALIBRATION The sealed source activity or kerma rate stated on the supplier's consignment details should be independently checked by an in-house radiation measurement. The confirmation check should be arranged before any clinical use of the new source and the results of the check be documented in the Source Register. Where the results of the check measurement vary by more than 5% from the certified activity or kerma rate, the source should not be used until further independent verification of the source activity has been conducted. A brachytherapy source calibrator should comply with the tolerances listed in the ACPSEM QA protocol (ACPSEM 1997) for Brachytherapy Source Calibrators. BRACHYTHERAPY: TREATMENT PLANNING The basic data for each available computer treatment planning program will need to be verified for: • • • correct exposure rate constant; parameters for tissue attenuation and scatter; source wall information;
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• • •
anisotropy; source activity; and the half-life of the radionuclide.
Isodose plans of point sources and line sources should be generated for comparison with published or measured data. The prescription and recording of brachytherapy doses should be in accordance with the international protocols of clinical dosimetry, notably ICRU Report 58 (ICRU 1997). BRACHYTHERAPY: TREATMENT DELIVERY All staff involved in caring for patients with implanted sources need to be familiar with the applicable safety precautions for both staff and visitors, and with protocols to deal with unexpected interruptions or emergencies. A portable radiation survey meter should be available for staff to check patients, equipment and the area of use for displaced sources so as to identify if a sealed source has: • • inadvertently remained inside a patient after completion of a treatment; or not been returned to its shielded container after use.
SUPERFICIAL BRACHYTHERAPY PROCEDURES A superficial brachytherapy source will need to be stored and handled so that direct handling is avoided. The surface of the plaque or mould containing the radioactivity should always be pointed, and held at as great a distance as possible, away from treatment personnel. The following applies to the use of radioactive plaques in the treatment of ophthalmological or dermatological conditions: • • • • the plaque should be appropriately labelled; the front surface of the plaque should not be viewed directly during any manipulations or examinations of the plaque due to its high dose rate; the active surface should never be scratched or damaged in order to preserve the integrity of the activity across the surface of the plaque; the plaque should be stored in a shielded container whilst not in use in a manner that protects the active face from damage by abrasion and with orientation that allows extraction without exposure to the active face; on initial receipt, a plaque will need to be commissioned for clinical use by a ROMP, and including a check measurement of the dose rate from the surface of the plaque; the dose rates used for calculations of treatment dose times will need to be adjusted for radioactive decay at intervals appropriate to the decay of the nuclide; the patient’s treatment should always correspond to the prescription of the prescribing medical practitioner; application or suturing of the plaque to the patient can only be performed by a person who is trained in its use and who is authorised by the relevant regulatory authority for the purpose; and sterilisation of the plaque will need to be by chemical means and not by boiling or autoclaving due to the risk of mishap resulting in damage to the plaque or release of radioactive material.
•
• • •
•
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For applicators loaded with radioactive sources for the treatment of ophthalmological or dermatological conditions: • • • the patient’s treatment should always correspond to the prescription of the prescribing medical practitioner; preparation of the applicator according to the medical prescription should always be undertaken by, or under the supervision of, a ROMP; and application or suturing of the applicator to the patient should only be performed only by a person who is trained in its use and who is authorised by the relevant regulatory authority for the purpose.
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Annex C
BRACHYTHERAPY SOURCES
General
Brachytherapy involves the use of radioactive sources placed within or immediately adjacent to the target volume. Brachytherapy sealed sources may be tubes, seeds, plaques, wire, applicators loaded with seeds, or equipment with encapsulated sealed source pellets. A sealed source is usually encased within an encapsulating jacket of a different substance, usually a metal or combination of metals. The encapsulating material acts to filter out unwanted effects such as low-energy radiation that contaminates the delivery of a therapeutic dose, and so permits accuracy in prescription. Size and shape of the source will depend upon its use, as will the surrounding filter that encases the source. Source placement may be performed by:
•
Manual insertion or application, in which the sources are directly implanted into or applied to the area of interest. This involves staff exposure and is the least desired form of delivery. Manual afterloading, where inert source guides are inserted within or adjacent to the target volume, and the radioactive sources are subsequently inserted manually into these source guides after surgery and imaging and planning procedures are completed. Remote afterloading, where inert source guides are inserted within or adjacent to the target volume during surgery, and the radioactive sources are subsequently inserted by remotely-operated automated machinery into these source guides after completing the imaging and planning procedures.
•
•
Remote afterloading should be used where practicable as it minimises exposure to the personnel involved. All HDR and PDR brachytherapy equipment is designed to be operated by remote afterloading to eliminate the need for staff proximity to the high activity sources exposed during treatment administration to the patient. The duration of placement of a sealed source will depend on the activity and dose rate being utilised. The source may be: • • • briefly placed for a pre-set treatment time (seconds or minutes) in or adjacent to the target volume ; temporarily placed and left in place for a pre-set treatment time (usually days) in or adjacent to the target volume; or permanently implanted in or adjacent to the target volume.
The placement of a sealed source may be:
• • • •
intracavitary: inserted into a body cavity; or intraluminal: placed in a hollow organ or vessel (intravascular); or interstitial: placed into a tumour or tissue; or superficial: placed against an external body structure (mould).
Table 1 summarises the brachytherapy sealed sources currently or potentially in use in Australia:
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TABLE 1: Sealed Source Brachytherapy
LOADING TYPE EQUIPMENT TYPE EXAMPLES
Nuclide
Placement
Use
REMOTE AFTERLOADING:
High Dose Rate (HDR) apparatus Pulsed Dose Rate (PDR) apparatus Low Dose Rate (LDR) apparatus
MANUAL AFTERLOADING:
Ir-192; Cs-137 Ir-192; Cs-137 Cs-137
brief application cyclic brief applications temporary
intracavitary; intraluminal; interstitial; superficial
intracavitary
gynaecology
tubes wire commercial applicator custom-built applicator stent
MANUAL INSERTION/APPLICATION:
Cs-137 Ir-192 Sr-90; P-32 Ir-192; Re-188 * e.g. Tc-96 **
temporary temporary brief application brief application permanent
intracavitary interstitial intraluminal intraluminal intraluminal
gynaecology gut; liver; breast intravascular intravascular intravascular
seeds seeds seeds plaque plaque applicator with seeds
Au-198 I-125 Pd-103 Sr-90 Ru-106 I-125
permanent permanent permanent brief application temporary temporary
interstitial interstitial interstitial superficial superficial (sutured) superficial (sutured)
tongue; pharyngeal; neck; prostate; breast breast ophthalmology (pterygia); dermatology ophthalmology (malignancies) ophthalmology (malignancies)
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* **
Liquid Re-188 contained in a balloon inserted into the artery is strictly an unsealed source, but is effectively a sealed source while inside the patient for the duration of the treatment. Permanent implants of radioactive stents are still under research development. This is included here as an example of the type of source that may be in use in this form in the future.
Note that radium-226 should not be used as a brachytherapy sealed source because of its inherent characteristic of build-up of radon gas and extreme hazards due to potential tube rupture and/or contamination leakage. Radon-222 seeds are no longer used in interstitial brachytherapy. Cobalt-60 is no longer used in eye applicators; less penetrating radionuclide alternatives (such as iodine-125) are now preferred. The use of strontium-90 plaques in ophthalmology and dermatology is decreasing due to superseding non-radioactive modalities.
Source Handling
The relative risks of the hazards of handling brachytherapy sources should be kept in perspective. The radiation hazard should not necessarily be assumed to be the overriding factor, other considerations such as infection from bodily fluids may also be important. The Radiotherapy or institution’s RSO should prepare and provide written instructions for radiation protection for any brachytherapy procedure involving manual handling of sources,
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or potential exposure to staff, visitors or public. These will contain details of specific restrictions for staff groups and the general public, with limitations on access based on the public dose limits. Care should be taken to ensure that the operator does not work without protection simply because working without it seems to be the ‘easy’ way. With proper training in the procedure and safe practice, a high degree of dexterity can be attained while still taking advantage of established methods of protection. If variation to methods of working is planned this should be discussed with the Radiotherapy RSO, and practised as a non-radioactive ‘dry run’ first. Detailed consideration of the safety of methods of sterilisation is needed, to avoid damage to a sealed source that might result in leakage or rupture. For example, radium-226 (which should not be in clinical use), caesium-137 and strontium-90 sources may not be heatsterilized. Heat-sterilisation requires purpose designed, temperature controlled equipment. Chemical sterilisation may be used, but attention should be paid to possible deleterious effects of some chemicals on sealed metal containers of radioactive sources and on any attached threads. Staff responsible for cleaning and sterilising of sealed sources will be trained appropriately to prevent damage or loss, and follow the recommended shielding and sterilisation procedures. Sealed radioactive sources require adequate shielding during sterilisation and until immediately before their insertion in the patient. Shield design should provide protection for the body and head, including the eyes. Where possible, shielding of the fingers and hands from beta rays should also be provided. Sources should be manipulated with long forceps, special remote handling devices or other suitable instruments. At times it may be impracticable to provide shielding protection for manual or manual afterloading cases, and in such circumstances it becomes essential to make best possible use of distance and speed of working. All manipulations with sealed sources should be carried out as quickly as possible, compatible with safe working practice. The skill of the operator is an important factor in reducing the amount of radiation received when radioactive sources are handled. A novice should therefore be trained with dummy sources or inactive material until a high degree of competence has been attained. Dummy sources should be clearly identified as such. All equipment used for manipulating sealed sources and loaded appliances should be designed and maintained to ensure safe and smooth operation and to minimise radiation exposure. Appliances should be so designed that sealed sources can be loaded easily and can be readily removed even when stuck by coagulable body fluids. Screw-threads should be carefully cut and be of optimum size and pitch to allow fast, jam-proof operation. Personal monitoring devices10 to measure exposure should routinely be worn when working with sealed sources. The ROMP or the RSO should ensure that all personnel (staff members or service technicians) operating brachytherapy devices (manual or automated afterloading equipment) and techniques are individually approved to use the sources and equipment. All staff working with brachytherapy devices, or associated with the care of patients undergoing treatment with such sources, should be fully trained and familiar in the proper operation of the device prior to treating patients, including emergency procedures.
Specific Brachytherapy Uses – Intravascular Brachytherapy
Intravascular brachytherapy is increasingly used to prevent re-stenosis in arterial vessels such as coronary or femoral arteries.
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Various radionuclides are used, either as sealed sources inserted briefly into the artery by automatic afterloading apparatus (e.g. phosphorus-32 and strontium-90 capsules, iridium192 wire), or as contained unsealed liquid sources inserted briefly into the artery by manual after loading techniques (e.g. liquid rhenium-188 contained in a balloon inserted into the artery, effectively making it a sealed source for the duration of the treatment but an unsealed source at all other stages). Intravascular brachytherapy involving permanently implanted radioactive stents is also under research development. Typical treatment doses for intravascular brachytherapy are 30 Gy to 0.5 mm TD in a single fraction, with a source activity such that the dwell time within the artery is typically several minutes. When the contained unsealed sources are used within the artery, the apparatus and procedure should be carefully designed to prevent all chances of the serious event of rupture of the containment during treatment. A guide to intravascular brachytherapy has been published (RSU/RAC 2000).
Specific Brachytherapy Uses – Ophthalmology and Dermatology
Strontium-90 Plaques for Operator Controlled Treatment Strontium-90 plaques are used for treatment of eye conditions (such as pterygia) and skin lesions. The plaque is typically a circular or elliptical curved disc of up to about 20 mm diameter. The strontium-90 (up to about 3 GBq) is contained in a 1 mm thick plate of silver, screened by 0.1 mm silver and protected against corrosion by a rolled gold coating. The plaque is mounted in an aluminium alloy case with a 1 mm deep guard ring. A stem handle is attached to the shielded back of the plaque mounting (in some cases the handle is screwed into the mounting and detachable). The dose rate from the concave front of the plaque is typically up to 0.15 Gy/sec. Treatment time per treatment session is typically of the order of 1 to 3 minutes for a prescribed dose of 8 Gy, with the operator using the handle to apply the source. The ancillary equipment required for these treatments includes an accurate stopwatch for accurate timing of the short treatment time. The manufacturer’s calibrated dose rate from the active surface of the plaque is usually stated to within ±20-30%, but it is desirable to establish a greater degree of accuracy by accurate measurement of the dose rate. The dose rate used for calculation of treatment time is generally adjusted annually for radioactive decay. When unshielded, these plaques are capable of delivering biologically significant doses within minutes. The handling techniques during use should therefore include ensuring the active side of the plaque is always directed away from the operator and other people (including the patient except for the actual period of treatment). The life of the strontium-90 plaque is considered by the manufacturers to be limited to 15 years, but may be longer subject to regulatory requirements and assuming it has been treated with care. Sterilisation of the plaque should be by isolated chemical means, and not by autoclaving or boiling. If the plaque is not handled with care, the active surface may become scratched or damaged in some way that will disrupt the integrity of the activity across the plate. This may result in
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shedding of the silver metal containing the strontium-90 and may compromise the even dose rate across the plate which is necessary for optimal patient treatment. The annual testing of the plaque surface should involve both wipe and immersion tests to demonstrate that there is no labile activity removable from the active plate. A visual (indirect) inspection should also be made to ascertain that the active surface is free from damage. It should be noted that the use of strontium-90 plaques in ophthalmology and dermatology is decreasing due to superseding modalities that do not use ionizing radiation. Scleral Attachments There are two types of radioactive scleral attachments in current use, namely plaque attachments and applicators loaded with radioactive seeds. Treatment is often done on outpatients who then return to the hospital or clinic at the end of the treatment for removal of the scleral attachment. The patient should wear an eye patch containing further shielding over the attachment (e.g. 1 mm lead for the iodine-125 seed eye applicator) for the duration of the treatment. The radiation dose rate in the vicinity of the patient when the applicator is in place should be able to be reduced to no more than 5 times natural background at 1 metre from the patient.
•
Plaque applicators with radioactive material such as ruthenium-106: (Note that cobalt-60 is no longer recommended because less penetrating alternatives are available). Ruthenium-106 applicators used for treatment of eye tumours are curved discs or kidney shapes, typically 11-25 mm diameter. The radioactive material (initially typically 10-20 MBq) is plated onto a silver substrate and screened by 0.1 mm silver. The dose rate at the centre of the applicator is of the order of 300-800 cGy/h. The beta radiation of the daughter rhodium-106 enables treatment of the eye up to depths of 8 mm. Treatment time (which will vary with applicator age, given the 372.6 day half-life of ruthenium-106) is typically 2-7 days for a prescribed dose to the tumour of 100-120 Gy. The manufacturer’s calibrated dose rate from the active surface of the plaque, which is usually stated to within ± 20-30%, has often been used as the calibration figure. However accurate calibration methods of the dose rate from the plaque are available to the ROMP and will ensure optimal treatment outcomes (which can otherwise be greatly reduced by as little as a 10% dose deviation). The dose rate used at each treatment should be adjusted for radioactive decay from the measured reference calibration. The applicator should be appropriately sterilised with respect to the requirements of the plaque surface and mounting materials. If the plaque is not handled with care, the active surface may become scratched or damaged in some way that will disrupt the integrity of the activity across the plate. This may result in shedding of the silver metal containing the radioactive material and may compromise the even dose rate across the plate which is necessary for optimal patient treatment. The annual testing of the plaque surface should involve both wipe and immersion tests to demonstrate that there is no labile activity removable from the active plate. A visual (indirect) inspection should also be made to ascertain that the active surface is free from damage. The life of a ruthenium-106 plaque is limited by the 372.6 day half-life.
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• Applicators loaded with radioactive seeds such as iodine-125 seeds: Iodine-125 seed applicators used for treatment of eye tumours are constructed of materials such as stainless steel and perspex, are typically 10 mm to 20 mm circular or elliptical diameter, and are loaded with typically 4-15 seeds up to a maximum of about 4 GBq. The dose rate at the front of the applicator is typically of the order of 50-60 cGy/h. The applicator geometry and seed activity are selected according to the treatment prescription. Prescribed doses and treatment times are typically: (melanoma) 80 Gy to apex of tumour in up to 6 days and (retinoblastoma) 40 Gy in 3-4 days. The applicator should be loaded with the radioactive seeds in a clean environment using standard safety procedures for handling of radioactive sources, such as handling the seeds with tweezers and working behind a bench shield. The loaded applicator should be appropriately sterilised with respect to the requirements of the seeds and of the applicator materials. After use, the applicator should be thoroughly cleaned and the seeds stored in a labelled shielded container for re-use or until they have decayed sufficiently to be disposed of as non-radioactive material (normally less than the IAEA Exempt Activity).
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Annex D
EQUIPMENT AND FACILITIES
INFORMATION RECORDS All radiotherapy equipment: An equipment inventory list should contain details of: • • • • • • • the type of equipment; the name of manufacturer; the model number; the serial number or other identifier; the year of manufacture; the date of commissioning; and the supplier of the equipment.
For radiation apparatus used for radiotherapy, the inventory list should detail the type and energy of radiation capable of being produced by the apparatus. For sealed source apparatus used for radiotherapy, the inventory list should include the following information: • • • • • • • • the original source certificate; details about the radioactive source including the name of the radionuclide, and its physical and chemical form; the source activity and its date of calibration; the name of the source manufacturer; the source model or design details; the serial number or other identifier; the date of source installation or the date of receipt of the source; and details of the manufacturer, model and serial number of the sealed source apparatus.
For radiotherapy equipment controlled by computer software or firmware, the inventory list should include the following information: • • • the names of the software modules; the versions in use; and date of the installation of the software.
For dosimetry equipment, including radiation survey meters, the inventory list should specify at least the following information: • • • • • the type of equipment; the name of the equipment manufacturer; the equipment model number; the equipment serial number or other identifier; the year of manufacture of the equipment; and
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•
the equipment’s calibration details.
BRACHYTHERAPY SOURCE REGISTER The Brachytherapy Source Register should be stored where the brachytherapy sources are usually stored. The Brachytherapy Source Register should contain, at least, the following information: • • • • • • • • • the name of each person authorised to store or use a source; the geographic location of the radioactive substances stores at the site; the location of each source within each radioactive substances store; the date of receipt of each source and the activity on that date; the physical and chemical form of the radioactive substance in each source; details of change(s) in the activity of the sources within brachytherapy device(s); details of all source changes or loadings; details of the movements of all sources from their usual place of storage; and detail the date and manner of ultimate disposal of each source from the site.
Each entry in the Brachytherapy Source Register should be accompanied by a signature, legibly printed name, and the date and time of the entry. Copies of the approved shielding specifications should be kept on site and include details of: • • • • the shielding design including details of the radiation source (including source configuration) for which the design was undertaken; the radiation shielding specifications; the radiation survey and assessment of the shielding effectiveness on completion of building works; and the maximum workload rating for the shielded premises.
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Annex E
QUANTIFICATION OF ERROR AND MONITORING OF INCIDENTS DELIVERY OF THE RADIOTHERAPY TREATMENT PROCESS
Background
By convention (ICRU 1993, ICRU 1999), the acceptable dose variation permitted across a target volume is limited to +7% to –5% of the prescribed dose. Errors considered to be of potential significance are those where the delivered dose is outside this accepted range of dose variation. Currently evaluation of error in treatment delivery is generally categorised by the size of the variation from the planned treatment: below 5%, 5-10% and above 10% variation. It is recognised by the radiation community that the accuracy of measurement of the delivery of a dose of external beam radiation treatment is a sum of all the errors (both random and systematic) in the machine, the planning dosimetry, the planning set-up and the treatment delivery. A total variation within 5% of the planned dose is considered as acceptable and appropriate clinical practice, although all effort should be made to reduce it to the lowest value possible. Variations less than 5% are unlikely to detectably influence outcome. It should be noted that a treatment error occurs not only when an inaccurate dose is delivered, but also when the wrong site is treated, or there is a geographical miss. Deviation of 10% or more from the prescribed dose is internationally accepted as being clinically detectable (ICRP 2000). In view of this it is considered by the Australian radiotherapy community to be a serious and reportable error. As such, the operator of the machine in question is required to inform the relevant authorities about the incident. The background to the incident should be investigated, and the cause(s) identified. Relevant changes to the procedural policies of the reporting site should be considered, and if necessary promulgated through the rest of the radiotherapy community. IN
THE
Collection of Treatment Incident Information
A treatment incident where the delivered dose is assessed as being over 5% but less than 10% from the prescribed dose11: • • • • is considered potentially clinically relevant; is not considered severe enough to merit formal report to the relevant regulatory authority; needs to involve the preparation of a detailed written report for the Responsible Person; and will be used as information for the internal quality assurance of the department but in such a way that the employee and the institution are protected from penalty.
Collection of Three Levels of Error in External Beam Radiotherapy
Detail and information on the incidence and type of error that occur in the delivery of external beam treatment should be collected in a formal and quantified fashion. It is recommended that a three-tiered system be utilised, whereby institutions collect information on the errors that can occur on a daily basis, allocating them into three levels. Detailed information on the efficacy of safety procedures, and the degree of adherence to policies will
11
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be collated through this approach, and intervention12 can be instituted by internal audit at a point before a major incident occurs. These levels are: Level 1 error: An error noted by the treating department, and assessed as being less than 5% of the total prescribed dose. This falls within the prescription delivery limitations, and thus is of no clinical significance. Occurrence and incidence of level 1 errors should be collected by the department for internal audit, as awareness of these errors will allow modification of treatment policies and will thus reduce the risk of the next level of error. No stigma should be attached to these errors, and the data should be collected in a fashion that renders it anonymous to both internal and external audit. Level 2 error: An error noted by the treating department and assessed as being over 5% but less than 10% of the total prescribed dose. This error is considered as potentially clinically relevant, but not severe enough to merit formal report to the relevant regulatory authority. It is unlikely that such an error would produce a detectable result. It will need to be collected as part of the internal QA of the department. Again, awareness of incidents at this level may highlight inadequacies in the procedural processes of the department, and may thus prevent errors of the next level. This information should be collected in a fashion that protects the employee and the institution from penalty. Level 3 error: An error in the prescription or delivery of the prescription that is greater than 10% of the prescribed dose. This level of error needs to be considered as significant and formally reported to the relevant authority as a radiation incident. This error may result in either over-dosage or under-dosage, both of which may have clinical significance. An internal audit will need to occur and policies revised if a flaw is identified. External review may also be instigated.
Incident Reporting for Brachytherapy
The delivery of dose in brachytherapy is subject to the same concerns regarding accuracy, but due to the nature of the technique, margins for dose variation are wider, in particular depending on the placement of the source(s). This is recognised and generally allowed for during target definition and dose prescription. If dose variation is identified beyond these limits, similar principles to incident recording and reporting should apply. Errors may arise in a similar fashion to those of external beam radiotherapy, with the additional possibility that geographic placement of the sealed radioactive source (or sources) may not occur exactly as planned. This is dependent on factors beyond current clinical capabilities to control. As such, the limitations in planning and placement, and the necessary adjustments that may be required, should be explained as part of the counselling and informed consent which patients are given prior to their treatment. Planning of brachytherapy should take into account both the potential to underdose the tumour target, and the potential to overdose surrounding normal structures. The tumour localisation and the dose prescription should acknowledge these possibilities and be designed to follow the optimal middle ground. Provided they are recognised and encompassed in the
12
Intervention is an action intended to reduce or avert exposure or the likelihood of exposure to sources which are not part of a controlled practice or which are out of control as a consequence of an accident or other event.
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treatment intent, deviations from the treatment plan within these defined constraints are not considered errors or incidents. Deviation beyond these limits should be recorded as above. As with external beam radiotherapy, other errors may occur, and all classes of error (including an unexpected shift in geographic position) should be recorded in a similar fashion so that the experience may be accumulated. As noted below under Monitoring of Incidents, if the source activity deviates by 15% or more, or the delivered dose by 10% or more from that prescribed, this should be recorded and reported.
Monitoring of Incidents
Current monitoring of incidents occurs at a national level through ARPANSA’s Australian Radiation Incidents Register (ARIR), which collates information on radiation incidents of types specified in the National Directory for Radiation Protection (ARPANSA 2004). Reports of incidents to the ARIR are usually provided by the radiation protection regulatory authorities of the Commonwealth, States and Territories. The National Directory for Radiation Protection requires reporting to the ARIR of the following circumstances relating to medical exposure of radiotherapy patients: • • when during the administration of a radioactive substance for therapeutic purposes, the activity administered differs from that prescribed by 15% or more; when during administration of a therapeutic dose of radiation from a radiation apparatus or a sealed radioactive source, the dose delivered differs from the total prescribed treatment dose by more than 10%; and any therapeutic treatment delivered to either the wrong patient or the wrong tissue, or using the wrong radiopharmaceutical.
•
In addition, the National Directory for Radiation Protection has general provisions for the reporting to regulatory authorities of other incidents, which could include near misses that may have led to incidents reportable under the above provisions. These span a wide continuum of delivery, communication and medical errors that are not satisfactorily captured by definitions of traditional dosimetric incidents. It is recommended that data on all minor incidents and potential errors be collected within treating departments. Any outcome (or near miss) which is unintended and has potential for harm to patient(s) or staff may be regarded as an incident by the relevant regulatory authority. Due to the repetitive and highly technical nature of radiotherapy administration, thousands of minor delivery errors occur across the country per year. The vast majority of these errors have no clinical consequence and are inevitable sequelae of clinical practice. However, pattern analysis of such data on a national scale may identify significant but otherwise unrecognised patterns of practice predicting for error or more major incident, which might therefore be averted. Such an approach is supported by the three professional groups (ACPSEM, RANZCR and AIR) integral to the delivery of radiotherapy (APSF/FRO/ ACPSEM/AIR 2002).
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Annex F
RADIATION WARNING SIGNS AND NOTICES
Radiation warning signs and notices, need to conform to Australian Standard AS 1319-1994, Safety signs for the occupational environment (Standards Australia 1994), and Australian Standard AS 2342-1992, Development, testing and implementation of information and safety symbols and symbolic signs (Standards Australia 1992). Examples of suitable warning notices are given below.
COLOURS FOR RADIATION WARNING SIGNS AND NOTICES
Background: Marking and trefoil: yellow black
EXAMPLE OF SUITABLE RADIATION WARNING SIGNS TO BE DISPLAYED ON THE OUTSIDE OF THE ENTRY DOORS TO ANY ROOM HOUSING RADIOTHERAPY EQUIPMENT
2880 2881
WARNING IONIZING RADIATION
2882
WARNING RADIOACTIVE MATERIALS
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EXAMPLE OF A SUITABLE WARNING SIGN AND NOTICE FOR A STORE OR STORAGE SAFE
STORE FOR RADIOACTIVE MATERIALS
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For a storage safe, the word ‘store’ in the above sign should be replaced by the words ‘storage safe’.
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Annex G
PROCEDURE FOR WIPE TESTING SOURCE HOUSING13
WIPE TEST REQUIREMENTS An annual wipe test should be carried out for each sealed source or its housing to check for contamination and for the integrity of its sealing, i.e. by wipe or smear testing each source or its housing and a record of each wipe test kept in the source record. Leak testing will need to be performed at 10-year intervals (see ISO 9978:1992) or whenever leakage is suspected with the particulars of the examinations be entered into the record. WIPE TEST METHODS14 If a wipe test is used to determine leak tightness after mechanical or thermal prototype testing, the sealed sources to be tested should be cleaned or decontaminated before the tests. Wet Wipe Test: Wipe all external surfaces of the sealed source thoroughly with a swab of filter paper or another suitable highly absorbent material, moistened with a liquid which will not attack the material of which the external surfaces of the sealed source are made and which, under the conditions of this test, has been demonstrated to be effective in removing any radioactive material present. Measure the activity of the swab. Dry Wipe Test: This test can be used in situations where it may not be appropriate to use a wet swab, for example for high activity cobalt-60 sources or in some recurrent inspections. To carry out the test, thoroughly rub all the external surfaces of the sealed source with a dry swab of filter paper and measure the activity. Approval Criteria: If the activity detected does not exceed 200 Bq, the sealed source is considered to be leaktight. A
SEALED RADIOACTIVE SOURCE
OR
13
14
The requirements in this Schedule have been adapted from AS 2243.4:1998, Safety in laboratories – Ionizing radiations (Standards Australia 1998), and ISO 9978:1992, Radiation protection – Sealed radioactive sources – Leakage test methods (ISO 1992). Wipe tests should be performed as close as possible to the sealed source, taking account of radiation protection issues. Page 76 of 92
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Annex H
SURVEY METERS
GENERAL REQUIREMENTS OF THE SURVEY METER Where a radiation survey meter is required, it should: • have sufficient measurement range to measure ambient dose equivalent rates or directional dose equivalent rates, as appropriate, at least throughout the ranges of 1 µSv.h-1, or its equivalent, to 2000 µSv.h-1, or its equivalent, for the radiations used in radiotherapy; continue to indicate, either visibly or audibly, when radiation levels exceed the maximum reading in any measurement range; and indicate the measured quantity with a measurement uncertainty not greater than ±25 percent inclusive of uncertainty due to response variation with energy over the range of energies of the radiation to be measured.
• •
CALIBRATION OF THE SURVEY METER Other than the mandatory calibration requirements specified in the Code, each radiation survey meter requires an operational and calibration check: • • • • before its initial use; at intervals not exceeding twelve months; following damage or repairs; and when otherwise indicated by its performance.
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Annex I
HEALTH EFFECTS OF IONIZING RADIATION CONTROL OF EXPOSURE
AND
STANDARDS
FOR
It is well known that high doses of ionizing radiation can cause harm, but there is continuing scientific uncertainty about effects at low doses. At levels of dose routinely encountered by members of the public and occupationally exposed persons, there is little or no epidemiological evidence of health effects. Radiation protection standards recognize that it is not possible to eliminate all radiation exposure, but they do provide for a system of control to avoid unnecessary exposure and to keep doses in the low dose range. Extreme doses of radiation to the whole body (around 10 sievert∗ and above), received in a short period, cause so much damage to internal organs and tissues of the body that vital systems cease to function and death may result within days or weeks. Very high doses (between about 1 sievert and 10 sievert), received in a short period, kill large numbers of cells, which can impair the function of vital organs and systems. Acute health effects, such as nausea, vomiting, skin and deep tissue burns, and impairment of the body’s ability to fight infection may result within hours, days or weeks. The extent of the damage increases with dose. However, ‘deterministic’ effects such as these are not observed at doses below certain thresholds. By limiting doses to levels below the thresholds, deterministic effects can be prevented entirely. Doses below the thresholds for deterministic effects may cause cellular damage, but this does not necessarily lead to harm to the individual: the effects are probabilistic or ‘stochastic’ in nature. It is known that doses above about 100 millisievert, received in a short period, lead to an increased risk of developing cancer later in life. There is good epidemiological evidence – especially from studies of the survivors of the atomic bombings - that, for several types of cancer, the risk increases roughly linearly with dose, and that the risk factor averaged over all ages and cancer types is about 1 in 100 for every 100 millisievert of dose (i.e. 1 in 10,000 per millisievert). At doses below about 100 millisievert, the evidence of harm is not clear-cut. While some studies indicate evidence of radiation-induced effects, epidemiological research has been unable to establish unequivocally that there are effects of statistical significance at doses below a few tens of millisieverts. Nevertheless, given that no threshold for stochastic effects has been demonstrated, and in order to be cautious in establishing health standards, the proportionality between risk and dose observed at higher doses is presumed to continue through all lower levels of dose to zero. This is called the linear, no-threshold (LNT) hypothesis and it is made for radiation protection purposes only. There is evidence that a dose accumulated over a long period carries less risk than the same dose received over a short period. Except for incidents and medical exposures, doses are not normally received over short periods, so that it is appropriate in determining standards for the control of exposure to use a risk factor that takes this into account. While not well quantified, a reduction of the high-dose risk factor by a factor of two has been adopted internationally, so that for radiation protection purposes the risk of radiation-induced fatal cancer (the risk factor) is taken to be about 1 in 20,000 per millisievert of dose for the population as a whole. If the LNT hypothesis is correct, any dose carries some risk. Therefore, measures for control of exposure for stochastic effects seek to avoid all reasonably avoidable risk. This is called optimising protection. However, risk in this sense may often be assessed in terms of risk to a ∗ The sievert (Sv) is a unit of measurement of radiation dose (see ARPANSA’s Recommendations for
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population, and may not ensure sufficient protection of the individual. Consequently, the optimisation approach is underpinned by applying dose limits that restrict the risk to individuals to an acceptable level. The fundamental regulatory philosophy is expressed in three principles, based on the recommendations of the International Commission on Radiological Protection (ICRP), which may be summarized as follows: Justification: human activities that cause exposure to radiation may be permitted only if they do more good than harm; Optimisation of protection: exposure to radiation from justified activities should be kept as low as reasonably achievable, social and economic factors being taken into account; and Limitation of individual dose: doses must not exceed the prescribed dose limits. Determining what is an acceptable risk for regulatory purposes is a complex value judgement. The ICRP reviewed a number of factors in developing its recommendations, which have in general been internationally endorsed, including by the World Health Organization, the International Labour Organisation and the International Atomic Energy Agency. Australia’s Radiation Health Committee, now established under the ARPANSA Act†, has recommended that the international standards be adopted in Australia. The recommended dose limits are summarized as follows: Limit on effective dose* For occupational exposure To limit individual risk 20 mSv per year, averaged over 5 years* For members of the public 1 mSv in a year*
*for details, see ARPANSA’s Recommendations for limiting exposure to ionizing radiation (2002)
In most situations, the requirements for limiting individual risk ensure that doses are below deterministic thresholds, but for cases where this does not apply, the recommended limits are as follows: Annual limit on equivalent dose* For occupational exposure To prevent deterministic effects in the lens of the eye in the skin in the hands and feet For members of the public
150 mSv 500 mSv 500 mSv
15 mSv 50 mSv –
*For details, see ARPANSA’s Recommendations for limiting exposure to ionizing radiation (2002)
In the case of occupational exposure during pregnancy, the general principle is that the embryo or fetus should be afforded the same level of protection as is required for a member of the public. For medical workers, the ICRP recommends that there should be a reasonable assurance that fetal dose can be kept below 1 mGy‡ during the course of the pregnancy. This guidance may be generalised to cover all occupationally exposed pregnant workers by keeping the fetal dose below 1 mSv. A full explanation of radiation protection principles and
The Australian Radiation Protection and Nuclear Safety Act (1998) The gray (Gy) is a unit of radiation dose. For X-rays and gamma radiation, it is essentially equivalent to the sievert.
‡ †
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of the recommended standards for Australia is given in ARPANSA/NOHSC Radiation Protection Series No. 1: Recommendations for limiting exposure to ionizing radiation (1995) and National standard for limiting occupational exposure to ionizing radiation (both republished in 2002).
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Annex J
ARPANSA RADIATION PROTECTION SERIES PUBLICATIONS
ARPANSA has taken over responsibility for the administration of the former NHMRC Radiation Health Series of publications and for the codes developed under the Environment Protection (Nuclear Codes) Act 1978. The publications are being progressively reviewed and republished as part of the Radiation Protection Series. All publications listed below are available in electronic format, and can be downloaded free of charge by visiting ARPANSA’s website at www.arpansa.gov.au/codes.htm. Radiation Protection Series publications are available for purchase directly from ARPANSA. Further information can be obtained by telephoning ARPANSA on 1800 022 333 (freecall within Australia) or (03) 9433 2211. RPS 1. Recommendations for Limiting Exposure to Ionizing Radiation (1995) and National Standard for Limiting Occupational Exposure to Ionizing Radiation (republished 2002) Code of Practice for the Safe Transport of Radioactive Material (2001) Radiation Protection Standard for Maximum Exposure Levels to Radiofrequency Fields – 3 kHz to 300 GHz (2002) Recommendations on the Discharge of Patients undergoing Treatment with Radioactive Substances (2002) Code of Practice and Safety Guide for Portable Density/Moisture Gauges Containing Radioactive Sources (2004) National Directory for Radiation Protection, Edition 1.0 (2004) Recommendations for Intervention in Emergency situations Involving Radiation Exposure (2004) Code of Practice for the Exposure of Humans to Ionizing Radiation for Medical Research Purposes (2005) Code of Practice and Safety Guide for Radiation Protection and Radioactive Waste Management in Mining and Mineral Processing (2005) Code of Practice and Safety Guide for Radiation Protection in Dentistry (2005)
RPS 2. RPS 3. RPS 4. RPS 5. RPS 6. RPS 7. RPS 8. RPS 9. RPS 10.
The Nuclear Codes Series have now all been republished. Those publications from the NHMRC Radiation Health Series that are still current are:
RADIATION HEALTH SERIES
RHS 2. RHS 3. RHS 4. RHS 8. RHS 9. Code of practice for the design of laboratories using radioactive substances for medical purposes (1980) Code of practice for the safe use of ionizing radiation in veterinary radiology: Parts 1 and 2 (1982) Code of practice for the safe use of radiation gauges (1982) Code of nursing practice for staff exposed to ionizing radiation (1984) Code of practice for protection against ionizing radiation emitted from X-ray analysis equipment (1984)
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RHS 10. Code of practice for safe use of ionizing radiation in veterinary radiology: part 3-radiotherapy (1984) RHS 13. Code of practice for the disposal of radioactive wastes by the user (1985) RHS 14. Recommendations for minimising radiological hazards to patients (1985) RHS 15. Code of practice for the safe use of microwave diathermy units (1985) RHS 16. Code of practice for the safe use of short wave (radiofrequency) diathermy units (1985) RHS 18. Code of practice for the safe handling of corpses containing radioactive materials (1986) RHS 19. Code of practice for the safe use of ionizing radiation in secondary schools (1986) RHS 21. Revised statement on cabinet X-ray equipment for examination of letters, packages, baggage, freight and other articles for security, quality control and other purposes (1987) RHS 22. Statement on enclosed X-ray equipment for special applications (1987) RHS 23. Code of practice for the control and safe handling of radioactive sources used for therapeutic purposes (1988) RHS 24. Code of practice for the design and safe operation of non-medical irradiation facilities (1988) RHS 25. Recommendations for ionization chamber smoke detectors for commercial and industrial fire protection systems (1988) RHS 28. Code of practice for the safe use of sealed radioactive sources in borehole logging (1989) RHS 29. Occupational standard for exposure to ultraviolet radiation (1989) RHS 30. Interim guidelines on limits of exposure to 50/60Hz electric and magnetic fields (1989) RHS 31. Code of practice for the safe use of industrial radiography equipment (1989) RHS 34. Safety guidelines for magnetic resonance diagnostic facilities (1991) RHS 35. Code of practice for the near-surface disposal of radioactive waste in Australia (1992) RHS 36. Code of practice for the safe use of lasers in schools (1995) RHS 37. Code of practice for the safe use of lasers in the entertainment industry (1995) RHS 38. Recommended limits on radioactive contamination on surfaces in laboratories (1995)
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References
Australasian College of Physical Scientists & Engineers in Medicine (ACPSEM) 1997, Recommendations for the Safe Use of External Beams and Sealed Brachytherapy Sources in Radiation Oncology, APSEM 20(3), Supplement, September 1997. Australian Patient Safety Foundation (APSF), Faculty of Radiation Oncology (FRO), Australasian College of Physical Scientists & Engineers in Medicine (ACPSEM) and Australian Institute of Radiography (AIR) 2002, Submission to Australian Council for Quality and Safety in Health Care (ACQSHC), ‘A three year proposal for a National Incident Monitoring Scheme in Radiation Oncology’, May 2002. Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) 2001, Code of Practice for the Safe Transport of Radioactive Material, Radiation Protection Series No. 2, ARPANSA, Yallambie. Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) 2002a, Recommendations for limiting exposure to ionizing radiation (1995), and National Occupational Health and Safety Commission (NOHSC) 2002, National standard for limiting occupational exposure to ionizing radiation, Radiation Protection Series No. 1, republished 2002, ARPANSA, Yallambie. Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) 2002b, Recommendations for the Discharge of Patients Undergoing Treatment with Radioactive Substances, Radiation Protection Series No. 4, ARPANSA, Yallambie. Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) 2004, National Directory for Radiation Protection, Edition 1.0, Radiation Protection Series No. 6, ARPANSA, Yallambie. Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) 2005, Code of Practice for the Exposure of Humans to Ionizing Radiation for Research Purposes, Radiation Protection Series No. 8, ARPANSA, Yallambie. Delongchamp, RR, Mabuchi, K, Yoshimoto, Y & Preston, DL 1997, ‘Cancer Mortality among Atomic Bomb Survivors Exposed In Utero or as Young Children, October 1950-May 1992’, Radiation Research, vol. 147, no. 3, pp. 385-395. Doll, R & Wakeford, R 1997, ‘Risk of childhood cancer from fetal irradiation’, The British Journal of Radiology, vol. 70, pp. 130-139. Institution of Physics and Engineering in Medicine and Biology (IPEMB) 1996, The IPEMB code of practice for the determination of absorbed dose for X-rays below 300 kV generating potential (0.035 mm Al–4 mm Cu HVL; 10–300 kV generating potential) Phys. Med. Biol. 41 2605–25 International Atomic Energy Agency (IAEA) 1996, International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources, Safety Series No. 115, IAEA, Vienna. International Atomic Energy Agency (IAEA) 1997, Absorbed Dose Determination in Photon and Electron Beams – An International Code of Practice, Technical Report Series No. 277, IAEA, Vienna. International Atomic Energy Agency (IAEA) 2000a, Lessons Learned from Accidental Exposures in Radiotherapy, Safety Reports Series No. 17, IAEA, Vienna.
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International Atomic Energy Agency (IAEA) 2000b, Absorbed Dose Determination in External Beam Radiotherapy: An International Code of Practice for Dosimetry Based on Standards of Absorbed Dose to Water, Technical Report Series No. 398, IAEA, Vienna. International Atomic Energy Agency (IAEA) 2002, Radiological Protection for Medical Exposure to Ionizing Radiation, Safety Standards Series No. RS-G-1.5, IAEA, Vienna. International Commission on Radiation Units and Measurements (ICRU) 1985, Dose and Volume Specifications for Reporting Intracavitary Therapy in Gynecology, ICRU Report 38, ICRU Publications, Bethesda, Maryland. International Commission on Radiation Units and Measurements (ICRU) 1993, Prescribing, Recording and Reporting Photon Beam Therapy, ICRU Report 50, ICRU Publications, Bethesda, Maryland. International Commission on Radiation Units and Measurements (ICRU) 1997, Dose and volume specification for reporting interstitial therapy, ICRU Report 58, ICRU Publications, Bethesda, Maryland. International Commission on Radiation Units and Measurements (ICRU) 1999, Prescribing, Recording and Reporting Photon Beam Therapy (Supplement to ICRU Report 50), ICRU Report 62, ICRU Publications, Bethesda, Maryland. International Commission on Radiation Units and Measurements (ICRU) 2004, Prescribing, Recording and Reporting Electron Beam Therapy, ICRU Report 71, ICRU Publications, Bethesda, Maryland. International Commission on Radiological Protection (ICRP) 1991, 1990 Recommendations of the International Commission on Radiological Protection, ICRP Publication 60, Annals of the ICRP Vol. 21 No. 1-3, Pergamon Press, Oxford. International Commission on Radiological Protection (ICRP) 1996, Radiological Protection and Safety in Medicine, ICRP Publication 73, Annals of the ICRP Vol. 26 No. 2, Pergamon Press, Oxford. International Commission on Radiological Protection (ICRP) 1998, Radiation Protection Recommendations as Applied to the Disposal of Long-lived Solid Radioactive Waste, ICRP Publication 81, Annals of the ICRP Vol. 28 No. 4, Pergamon Press, Oxford. International Commission on Radiological Protection (ICRP) 2000, Prevention of Accidental Exposures to Patients Undergoing Radiation Therapy, ICRP Publication 86, Annals of the ICRP Vol. 30 No. 3, Pergamon Press, Oxford. International Organization for Standardization (ISO) 1992, Radiation protection - Sealed radioactive sources - Leakage test methods, ISO 9978:1992, ISO, Geneva. Kutcher et al. 1994, ‘Comprehensive QA for radiation oncology: Report of AAPM Radiation Therapy Committee Task Group 40’, Medical Physics, vol. 21, no. 4, pp. 581-619. Nath, R, Anderson, LL, Meli, JA, Olch, AJ, Stitt, JA & Williamson, JF 1997, ‘Code of practice for brachytherapy physics: Report of the AAPM Radiation Therapy Committee Task Group No. 56’, Medical Physics, vol. 24, no. 10, pp. 1557-98. National Radiological Protection Board (NRPB) 1991, Board Advice Following Publication of the 1990 Recommendations of ICRP, NRPB-M321, NRPB, Chilton.
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Radiation Safety Unit (RSU) and Radiation Advisory Committee (RAC) 2000, Guidelines for Intravascular Brachytherapy, Publication No. 0461000, Radiation Safety Unit, Dept of Human Services, Victoria. [Refer www.dhs.vic.gov.au/phd/hprot/rsu/radsaf.html] The Royal Australian and New Zealand College of Radiologists (RANZCR) 2005, Medical and Dosimetry Record Storage Requirements for Radiation Oncology, Faculty of Radiation Oncology, RANZCR – April 2005. Standards Australia 1992, Development, testing and implementation of information and safety symbols and symbolic signs, AS 2342-1992, Standards Australia, Sydney. Standards Australia 1994, Safety signs for the occupational environment, AS 1319-1994, Standards Australia, Sydney. Standards Australia 1997, Laboratory design and construction – General requirements, AS/NZS 2982.1:1997, Standards Australia, Sydney. Standards Australia 1998, Safety in laboratories – Ionizing radiations, AS 2243.4:1998, Standards Australia, Sydney. Van Dyk, J, Barnett, R, Cygler, J & Shragge, P 1993, ‘Commissioning and quality assurance of treatment planning computers’, International Journal of Radiation Oncology - Biology - Physics, vol. 26, pp. 261-73. Some web sites of organisations where information on radiation protection in radiotherapy may be obtained are: International Atomic Energy Agency (IAEA): http://www.iaea.org/ International Commission on Radiological Protection (ICRP): http://www.icrp.org/ International Commission http://www.icru.org/ on Radiation Units and Measurements (ICRU):
National Radiological Protection Board (NRPB): http://www.nrpb.org/
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Glossary
Absorbed dose the energy absorbed per unit mass by matter from ionizing radiation which impinges upon it. Absorbed dose, D, is defined by the expression:
D=
dE dm
where dE is the mean energy imparted by ionizing radiation to matter of mass dm. The unit of absorbed dose is joule per kilogram (J kg-1), with the special name gray (Gy). Approved medical practitioner a medical practitioner holding qualifications necessary for registration by the relevant professional body to allow that medical practitioner to prescribe a radiotherapy treatment. Authorisation a written permission granted by the relevant regulatory authority to perform specified practices. The form of an authorisation can include a licence, registration, or accreditation. Brachytherapy (brachy from the Greek for ‘near’, and therapy : treatment) involves the use of radioactive sources placed within or immediately adjacent to the target volume. Contamination the presence of radioactive substances in or on a material or the human body or other place where they are undesirable or could be harmful. Defence in depth the application of more than a single protective measure for a given safety objective such that the objective is achieved even if one or more of the protective measures fails. Deterministic effect an effect, such as partial loss of function of an organ or tissue, caused by radiation and manifest only above some threshold of dose, the severity of the effect depending upon the dose received. Dose constraint a prospective restriction on anticipated dose, primarily intended to be used to discard undesirable options in an optimisation calculation. in occupational exposure, a dose constraint may be used to restrict the options considered in the design of the working environment for a particular category of employee. in medical exposure, a dose constraint for volunteers in medical research may be used to restrict the options considered in the design of an experimental protocol. in public exposure, a dose constraint may be used to restrict the exposure of the critical group from a particular source of radiation. Effective dose a measure of dose which takes into account both the type of radiation involved and the radiological sensitivities of the organs and tissues irradiated. Effective dose, E, is the sum of weighted equivalent doses in all organs and tissues of the body. It is given by the expression:
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E = ∑ wT H T
T
where HT is the equivalent dose in organ or tissue T and wT is the weighting factor for that organ or tissue T. The unit of effective dose is the same as for equivalent dose, J kg-1, with the special name sievert (Sv). Employee a person who works for an employer within an operation. Employer an operator who or which engages people to work within an operation; the term employer includes a self-employed person. Equipment servicing agency A person involved in the commissioning, maintenance or repair of radiotherapy equipment who is, or who employs, a service engineer or technician. Equivalent dose a measure of dose in organs and tissues which takes into account the type of radiation involved. Equivalent dose, H, is a weighted dose in an organ or tissue, with the radiation weighting factor(s) determined by the type and energy of the radiation to which the organ or tissue is exposed. The equivalent dose HT in organ or tissue T is given by the expression:
H T = ∑ w R DT , R
R
where DT,R is the absorbed dose averaged over the organ or tissue T due to radiation R and wR is the radiation weighting factor for that radiation. The unit of equivalent dose is the same as for absorbed dose, J kg-1, with the special name sievert (Sv). Exposure the circumstance of being exposed to radiation, a defined dosimetric quantity now no longer used for radiation protection purposes. (The context in which the word is used should avoid ambiguity.) General supervision the exercise of control over radiation safety without the person exercising such control necessarily being present on the premises of operation. Half-life in relation to radioactive decay, the time required for the quantity of a radionuclide to decrease to one half of its initial value. ICRP the International Commission on Radiological Protection. It is an independent organisation that provides general guidance on radiation protection. The recommendations of the ICRP are not legally binding, but are generally followed by countries framing national regulatory requirements. ICRU
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either: or:
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the International Commission on Radiation Units and Measurements. Ionizing radiation radiation which is capable of causing ionization, either directly (for example: for radiation in the form of gamma rays and charged particles) or, indirectly (for example: for radiation in the form of neutrons). Ionizing radiation apparatus an apparatus that produces ionizing radiation when energised, or when assembled or repaired is capable of doing so when energised. Justification the notion that human activities which lead to exposure to radiation should be justified, before they are permitted to take place, by showing that they are likely to do more good than harm. Medical exposure exposure of a person to radiation received as a patient undergoing medical diagnosis or therapy, or as a volunteer in medical research, or non-occupational exposure received as a consequence of assisting an exposed patient. Occupational exposure exposure of a person to radiation which occurs in the course of that person’s work and which is not excluded exposure15. Optimisation the process of maximising the net benefit arising from human activities which lead to exposure to radiation. Practice a type of human activity; in a radiological context, a human activity which may result in exposure to ionizing radiation and to which a system of radiation protection applies. Prescribed radiotherapy treatment means an order, in written or electronic form, for the intentional irradiation of a person for therapeutic purposes, stating: (a) (b) particulars of the radiation source to be used; and the amount, and method of delivery, of the radiation.
Prescribing practitioner the approved medical practitioner who wrote the prescription for a particular patient’s treatment. Public exposure exposure of a person, or persons, to radiation which is neither occupational nor medical exposure.
15
Excluded exposure is, in the context of occupational exposure, the component of exposure which arises from natural background radiation, provided that any relevant action level, or levels, for the workplace are not exceeded and that the appropriate authority does not prohibit its exclusion. Page 88 of 92
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Qualified expert a person who: (a) (b) is qualified in the application of the physics of therapeutic or diagnostic uses of ionizing radiation; and has been recognised by the relevant regulatory authority as being able to perform the dosimetric calculations, radiation measurements and monitoring relevant to the person’s area of expertise16.
Radiation incident any unintended or ill-advised event when using ionizing radiation apparatus, specified types of non-ionizing radiation apparatus or radioactive substances, which results in, or has the potential to result in, an exposure to radiation to any person or the environment, outside the range of that normally expected for a particular practice, including events resulting from operator error, equipment failure, or the failure of management systems that warranted investigation. Radiation Oncology Medical Physicist (ROMP) for the purpose of the Code and this Safety Guide, is a person who is qualified to perform the necessary dosimetric calculations, measurements and monitoring. A suitable person will (a) (b) be on the Register of Radiation Oncology Medical Physicists held by the Australasian College of Physical Scientists and Engineers in Medicine; or have an equivalent level of training, skills, knowledge and expertise to a person listed on the Australasian College of Physical Scientists and Engineers in Medicine’s Register of Radiation Oncology Medical Physicists as determined by the relevant regulatory authority.
Radioactive material material which spontaneously emits ionizing radiation as a consequence of radioactive decay. Radiotherapy equipment means an ionizing radiation apparatus or a sealed source apparatus. Relevant regulatory authority the radiation protection authority or authorities designated, or otherwise recognized, for regulatory purposes in connection with protection and safety relating to medical applications of ionizing radiation. Responsible person in relation to any radioactive source, radiation-producing equipment, prescribed radiation facility or premises on which radioactive sources are stored or used means the legal person17: (a) having overall management responsibility including responsibility for the security and maintenance of the source, radiation-producing equipment, facility or premises; (b) having overall control over who may use the source, radiation-producing equipment, facility or premises; and
16 17
Competency requirements for a qualified expert will be listed in future editions of the National Directory for Radiation Protection. A legal person can be a natural person, a body corporate, a partnership or any other entity recognised as a “legal person” by the legislation in the jurisdiction. Page 89 of 92
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(c) in whose name the source, radiation-producing equipment, facility or premises would be registered if this is required. Sealed source radioactive material that is permanently sealed in a capsule or closely bounded and in a solid form. Sealed source apparatus an apparatus that produces ionizing radiation by virtue of the fact that it contains radioactive material in the form of a sealed source. Stochastic effect an effect known to occur sometimes as a consequence of exposure to radiation, but which may or may not be expressed in a particular exposed person, the likelihood of the effect occurring being a function of the dose received. Supplier any person who designs, manufactures, produces, constructs, leases, or hires out radiotherapy equipment. (An importer of radiotherapy equipment is considered a supplier of the radiotherapy equipment). Teletherapy (tele from the Greek for ‘at a distance’) involves the use of irradiating equipment to deliver radiation doses to a target tissue volume at a distance from the target tissue. Teletherapy equipment includes: • • • X-ray tubes using beam of ionizing radiation generated electronically to produce kilovoltage X-ray beams, for direct field treatment; linear accelerators using electron beams to produce photons or electron beams of megavoltage energy, using either isocentric mounting or directional mounting (generally intra-operative devices); and Sealed radioactive substances as the source of ionizing radiation, using isocentric mounting or direct field treatment.
X-ray ionizing electromagnetic radiation emitted during the transition of an atomic electron to a lower energy state or during the rapid deceleration of a charged particle.
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Contributors to Drafting and Review
WORKING GROUP
Professor Gillian Duchesne Ms Mary Aerts Mr Dominic Au-Yeung Dr Brad Cassels Mr Peter Collins Dr Michael Izard Ms Heather Letwin Assoc Professor Lyn Oliver Dr David Webb Director of Radiation Oncology, Peter MacCallum Cancer Centre, Victoria (Convenor) Radiation Health Section, Health Department of Western Australia Chief Radiation Therapist, Austin Health, Victoria Manager, Radiation Safety Program, Department of Human Services, Victoria Principal Medical Scientist, Royal Adelaide Hospital, South Australia Radiation Oncology Associates Pty Limited, New South Wales Standards Development & Committee Support Section, ARPANSA Principal Medical Physicist, Radiation Oncology, Royal North Shore Hospital, and Institute of Medical Physics, The University of Sydney, New South Wales Manager, Ionizing Radiation Standards Section, ARPANSA
ORGANISATIONS/PERSONS CONTRIBUTING TO THE DEVELOPMENT OF THE PUBLICATION
Mr Simon Critchley Mr Keith Dessent Mr Alan Melbourne Director, Radiation Health, Department of Health, Queensland Standards Development & Committee Support Section, ARPANSA Manager, Standards Development & Committee Support Section, ARPANSA
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Index
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