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powerpoint about picture archiving and communication system.
powerpoint about picture archiving and communication system.
PICTURE ARCHIVING AND COMMUNICATION SYSTEMS (PACS) chayanika PACS A picture archiving and communication system (PACS) is a comprehensive computer system that is responsible for the electronic storage and distribution of medical images in the medical enterprise AIM OF PACS To replace conventional analogue film, paper clinical request forms and reports - with a completely computerized electronic display whereby digital images are viewed on monitors in conjunction with the clinical details of the patient and the associated radiological report displayed in electronic format. Must replace functions of traditional X ray film i.e. image acquisition, storage, transportation and display Must improve upon a film based system in a cost–neutral manner The PACS Project Team Most PACS decisions take upwards to two years from initial planning through contract negotiations and employs a team of people from: Radiology- Radiologists, Techs Information Systems- I/S support, networking, etc. Administration (CIO, CFO, VP, etc.) Purchasing Staff Physicians and Nursing staff Outside Consultant Key components of PACS Digital acquisition devices Network Database server Archival system RIS Soft-copy display workstations Remote access PACS & Its Components (1) Acquisition (2) Storage (3) Display DICOM Modality DICOM Server Diagnostic WS CT, MR Clinical WS DSA, CR, DR, RI Non-DICOM Laser Imager Storage & Printer Server Archive DICOM Video Acq. WS US, ES Laser Imager 7 Non-DICOM Modality (4) Network PACS Hardware To acquire- digital DICOM compatible acquisition devices To display- bright monitor To transport- fast network To store- large archive and database (efficient data management) Digital Imaging Digital imaging is a broad term. Term was first used medically in 1970s in computed tomography (CT). Digital imaging is defined as any image acquisition process that produces an electronic image that can be viewed and manipulated on a computer. In radiology, images can be sent via computer networks to a variety of locations. An electronic digital image is made up of a matrix of tiny Picture elements called as Pixels Bit depth for a pixel Each pixel is represented by a digital value. This value in turn corresponds to a specific colour or a shade of gray. Bit depth 1 = only black and white shade Bit depth 8 = 256 shades of color Bit depth 24 = 16 million colors DIGITAL IMAGE CHARACTERISTICS Resolution - number of pixels Color shade info - Bit depth Image file size - depends on the above two factors expressed in KB or MB Image file format -Bitmap, Gif, Jpeg, Tiff, DCM Uncompressed or compressed Resolution of an image Dots per inch (DPI) Also described in pixels per image of a given size e.g. 800x600 pixels. More number of pixels per image of a given size means a greater resolution. 800x600 10.5‖x8‖ 76 DPI 1024x768 10.5‖x8‖ 96 DPI Calculation of Image file size 800x600 x8 = 469kB > 0.469 MB 76 DPI2 * 10.5‖x8‖ x 8 FILE SIZE ALSO DEPENDS ON IMAGE FORMAT BMP (Windows Bitmap) TIFF (Tagged image file format) GIF (Graphic interchange format) JPEG (Joint photographic experts group) Images on monitors Monitors also have a defined ability to reproduce shades of colour or gray tone. -monochrome CRT (1bit) -CGA (16 colour- 4 bit) -VGA (256 colour - 8 bit) -SVGA (16 million colours - 24 bit) The amount of the image that can be displayed at once depends on the relationship of the image’s pixel dimensions (or dpi) to the monitor’s desktop setting. Suppose an image has 800*600 pixel resolution. And this is being displayed on a monitor set to 640*480 pixel resolution. Then only part of that image covered by these many pixels will be displayed resulting in incomplete display. The percentage of an image displayed can be increased several ways, by increasing the screen resolution and/or by decreasing the image resolution Dimensional fidelity This can be achieved when digital image resolution equals the monitor’s resolution (dpi) Comparative image sizes from different modalities modality matrix Bit depth Image size mammograph 4000*6000 12 50 MB y Radiography 2500*2000 10 or 12 10 MB Digital fluro 1000*1000 8 or 10 1 or 2 MB Digital Cine 1000*500 8 or 10 1 MB CT 512*512 16 524 KB MRI 256*256 16 131 KB USG 512*512 8 262 KB Nuclear med 64*64 16 8 KB 1 k image = 1024*1024 and 2k = 2048*2048 DIGITAL IMAGE ACQUISITION 3 methods Digitizing conventional analogue film Photostimulable phosphor plate technology, computed radiography (CR) Direct digital radiography (DR) DIGITIZATION OF ANALOGUE FILM Time consuming process that requires skilled operators image retains intrinsic limitations present in the Digitized analogue film Not practical on a large scale Necessary in a PACS environment- to allow analogue films acquired at a non-PACS institution to be entered onto the PACS COMPUTED RADIOGRAPHY (CR) Commonest means of acquiring plain radiographic images in a digital format Phtostimulable phosphor plates replace conventional film/screen combination Phosphor plates are reusable (thousand or more exposures) Can be used with standard X-ray equipment CR is suitable for mobile radiographic work COMPUTED RADIOGRAPHY Digital Cassette reader COMPUTED RADIOGRAPHY (CR) Flatter, more linear, optical density versus radiation exposure response curve than the classic sigmoid-shaped curve of the conventional film/screen combination Greater latitude of exposure - useful under challenging circumstances e.g. in ICU , and in the area behind the cardiac silhouette and the lung vessels, or the soft tissues of the neck and the cervico-thoracic junction Reduction in number of repeat images Lower spatial resolution (2.5 line-pairs/mm) ) than that of film (approximately 5 line-pairs per mm), Superior contrast resolution DIRECT DIGITAL RADIOGRAPHY (DR) Amorphous silicon is used with a digital detector Detectors- caesium iodide or rare earth scintillators which emit light photons or selenium which produces an electrical signal (i.e. direct digital signal) Detector plates are heavy, fragile and fixed Only very recently been adapted for use in mobile direct DR apparatus ( much more expensive than the phosphor plate alternative). X-ray photons X-ray photons Caesium Iodide Selenium light Amorphous silicon Amorphous silicon Photodiode/Transistor array Photodiode/Transistor array electrons electrons Read out electronics Read out electronics Digital signal Digital signal DIRECT DIGITAL RADIOGRAPHY Spatial resolution of DR equals that of film DR has better detective quantum efficiency (DQE) thus allowing dose reduction/exposure and better contrast resolution Produces direct digital signal and there is no manual processing of plates High cost PACS WORKSTATIONS 1. Primary diagnostic workstations- imaging department 2. Review workstations- rest of the hospital including OT, OPDs VIEWING STATIONS Diagnostic Workstations 2, 3 or 4 Monitor Workstations 2, 3 or 5 Megapixel Displays Combination 2 (3 or 5 Mpixel Monitor for Reporting) 1 (1280 X 1024 Monitor for RIS, Mail, Voice Recognition etc.) Flat vs CRT Clinical / Orthopedic Workstations 1 or 2 Monitor Workstations Flat vs CRT Web Client Workstations 1 or 2 Monitor Workstations Flat vs CRT MONITORS Resolution - A digital chest radiograph(plain radiography) requires a monitor : 3 megapixels (for spatial resolution) Greyscale, not colour Other images (e.g. CT, MR, US, NM, angiography or fluoroscopy) - 1 megapixel monitor Digital mammograms - a 5 megapixel monitor MONITORS Brightness- 10 times less than conventional view box. B/W monitors- brighter than colour monitors, greater range of grey scale, Colour monitors- doppler, nuclear medicine, PET, post processed images Ambient lighting - dark (black or navy) blackout blinds fitted to the windows, and dimmer switches fitted to the room lighting. Monitors should not be placed opposite a window On the wards, the workstations should be sited off the main ward . new hardware development is the manufacture of dual-monitor computers (with one central processing unit (CPU), one graphics card and one keyboard). two chest radiographs from the same patient could be compared simultaneously, at large size, one on each monitor. CRT- CATHODE RAY TUBE LCD- LIQUID CRYSTAL DISPLAY Cost one-half to one-third as a Preferable comparable LCD. Medical LCDs are brighter than Can be viewed from a wide medical CRTs. angle - several users view the Flat-panel monitor -the amount of image at the same time. desk space required is Luminosity degrades relatively substantially less. quickly- need to be replaced A fixed geometry - aspect ratio more often never changes. Curved screen causes Capacity to dynamically change distortion of the image their luminosity so that the The aspect ratio (the ratio of perceived brightness is constant height to width can be varied. . images may appear too tall or too wide if deviated from its calibration settings GRAPHIC USER INTERFACE Screen layout and computer tools presented to the user Contrast width and level CT density value Greyscale inversion Image orientation Magnification Annotation ‘PACS workstations’ versus ‘web browsers’ The only difference is their software. ‗PACS workstation‘ refers to a high-specification computer that runs proprietary sophisticated software dedicated to image diagnosis and review ‗PACS web browser‘ depends upon a public domain web browser (usually Internet Explorer) to display images for review purposes, and can be loaded on any off-the-shelf computer. PACS web browser can also perform numerous other functions (e.g. making slides, writing documents, accessing the Internet etc.) depending upon which software packages have been loaded onto it PACS SOFTWARE CONCEPTS Proprietary, and vendor specific Sophisticated PACS software is essential to the radiologist to allow the PACS to be used efficiently. 4 main software concepts Prefetching or Preloading Worklists and folders Default display protocols or hanging protocols Reporting/dictation macros or worklists PREFETCHING OR PRELOADING Retrieval of previous images of a patient from the long term archive onto the short –term storage device, prior to new imaging examination on that patient Prefetch algorithms- Software programs that automatically retrieve historical examination results and reports for correlation with the current study Prefetching algorithms rely upon connections with HIS and RIS WORKLISTS AND FOLDERS Subdividing the vast amount of imaging data acquired onto the PACS into clinically relevant, easily accessible subgroups Worklists- work that has to be done Folders- grouping of reported examinations in different ways (eg. by body part or by referring clinician) Depending upon the nature of the workflow in a particular institution - worklists and folders will differ DEFAULT DISPLAY PROTOCOLS (DDP) Software for displaying the images of current and related previous examinations in a predetermined arrangement on the workstation monitors as per the wish of radiologist or clinician Based on the anatomic region, examination type, technique, and pathologic condition; customized and made user specific (based on login) and user configurable Save user time – images not to be rearranged on the monitors prior to reporting or viewing. REPORTING/DICTATION MACROS OR WORKLISTS Software that enables the radiologist to work through a reporting worklist in a efficient and time saving manner Minimizing the number of commands necessary to accomplish various steps Automatically skips displaying the next exam in the reporting worklist if it has already been opened in reporting macro mode by another radiologist, working at a different workstation A useful refinement - is to have an intermediate status assigned to examinations if they have been reported by a junior radiologist and require checking at a later time Networking Computer network is a communication system for a collection of interconnected computer devices. exchange of information multiple access of centralized information resource sharing Medium for transmission Medium Distance Cost Copper Twisted pair 100 mtr Low Coaxial thick Coaxial thin Optical 150 km High fibre Network Topologies BUS Used in Ethernet Simplicity Difficult to trace problems when a channel fails A C E B D F Ring Simple In a single ring, the network fails if the channel between two nodes fails. A C E B D F Star (Hub) High speed Ethernet switch, ATM switch simple to isolate a fault single point failure at switch C E A B D F Mesh Complicated C E A B D F LAN – local area network for a lab, floor or department MAN – metropolitan area network for a building, campus or a city WAN- wide area network for city, province or country – interconnects LAN and MAN LAN Types Ethernet 10 Mbps Fast Ethernet 100 Mbps Token ring Asynchronous tranfer mode – different transmission media can be used together Hubs – signal amplification for onward transmission Switches – additional capabilities of switching the connectivity to between two nodes Routers – increases efficiency by limiting traffic between network segments Modern hospitals have a switched network - allows the whole bandwidth (e.g. 100 Mbps ethernet) available to each switch in the network Hub network - the entire hub accommodates the total bandwidth (e.g. the 100 Mbps) - all the attached items have to share a portion Bandwidth The maximum rate at which data can pass between two points in the network. Bandwidth depends - the transmission medium (copper wires, fiberoptics, wireless) the number of computers sharing the same infrastructure The time required for an image to be sent from a PACS server to a workstation depends – the bandwidth of the intervening network the number of simultaneous requests from users. PACS should be granted dedicated bandwidth used only by PACS workstations and servers. Prevents nonessential data transmissions from interfering with departmental productivity Image compression is a means of decreasing the bandwidth needed to transmit images rapidly LOSSLESS - compression scheme - very detail of the original image can be faithfully restored LOSSY DATABASES AND ARCHIVE Store information identifying patients and cataloguing their studies Images are stored separately in components specially designed to provide rapid access Use single relational database like Sybase, Oracle or Microsoft access Should provide rapid responses to queries of the user SHORT TERM STORAGE Examination retrievable in 2 s or less Fault-tolerantRAID devices (containing magnetic disks)- expensive, very high performance LONG TERM STORAGE Examination retrievable in 2 min or less Compact disks (CD-ROMs)- 650 MB Magneto-optical disks (MODs)- 6 GB Digital versatile disks (DVD)- 16 GB, secure medium Fluorescent multilayer disk (FMD)- 50 GB The standard computer hard drive or magnetic disk, also known as a direct-access storage device, is the fastest medium from which to retrieve data. Presently available devices have a capacity of 10–200 Gbytes and a rapidly decreasing cost. THIRD LEVEL STORAGE Ultra long term back up Stored on- or off-site Medium should be cheap, need not be rapidly accessible Digital linear tape (DLT)- 35Gb Tapeas secondary level storage- to reduce cost- DLT, AIT (advanced intelligent tape, Sony) Online versus off line ONLINE STORAGE - Some of the data on a PACS are immediately available whenever a radiologist requests them. usually includes the most recent images and their relevant comparison studies. OFF-LINE STORAGE – refers to less accessible archive images and need to be restored to online status before they can be viewed. In a single-tier storage system, all the data are online all the time and are stored on a single medium (usually spinning disks). In a multitier storage system,some of the data are online (usually on spinning disks), while other data are off line (usually on optical media or tape). Amount of storage Determining storage requirements is one of the most difficult aspects of planning a PACS. The proper ratio of online to off-line storage, as well as the proper storage media There are two important principles in determining storage requirements: (a) Storage is easy to underestimate—the PACS will probably need more storage than planners suspect (b) the system must easily accommodate additional storage at a reasonable cost in the future. Storage Requirements per Modality Image Size Average # of Images/Exam Storage Requirements Average # of Exams/Year REDUNDANCY Medical imaging data are of critical importance - unacceptable to permit one computer error to destroy all copies of the data REDUNDANCY refers to storage of multiple copies of imaging data. Also used when several computers or network components perform the same job—if one element fails, the redundant elements keep the system functioning until the failed component can be replaced. A redundant array of inexpensive disks (RAID) is the most frequently used redundancy system In a RAID, the data are spread over several hard drives, such that if any one drive fails, the data can be reconstructed from the surviving drives. PACSwith a single-tier architecture must have another backup system for archiving in case the main storage fails. (This backup system usually takes use of inexpensive storage media A third form of redundancy is related to disaster recovery. Additional copies of data are stored at a geographically distant site as an extreme emergency backup. ACRONYMS: DICOM, HL7 AND IHE DICOM (Digital image communication in medicine) Itis a "co-operative standard" that allows compatibility between imaging systems An international standard for interchange of biomedical images and image-related information Each image is associated with a header information about the patient, the date, the series, parameters of acquisition etc. Hence can not be lost or misplaced Theformat is independent of different machines and communication protocols History and evolution of DICOM standard In early eighties, the American College of Radiologists (ACR) and National Electrical Manufacturers Association (NEMA) acknowledged need for a standard - facilitate connectivity of imaging and associated medical equipments of different vendors The first and earliest official Standards Publication titled ACR/NEMA No. 300-1985, referred to as version 1.0 was released in 1985, with an aim to "promote communication of digital image information, regardless of device manufacturer, facilitate development and expansion of picture archiving and communication systems (PACS)―. Need for DICOM standard It offers a range of beneficial features : It facilitates multi-vendor connectivity. It obtains the images of patient and all epidemiological information associated with it, in an identical format. It obtains non-image data like waveforms, reports, ECG (12-lead, continuous, Holter), hemodynamic (pressure), voice, audio etc. by creation of explicit "information objects―. It allows interconnection and interaction ("interoperability") of equipments and transfer of data. It enables integration of scanners, servers, workstations, printers, and network hardware from multiple vendors into a PACS. It therefore promotes the development of PACS and image networking in LAN and WAN. ROLE OF DIGITAL IMAGING AND COMMUNICATIONS IN MEDICINE IN RADIOLOGY PRACTICE DICOM conformance statement This is essentially a vendor's claim of compliance to the DICOM standard, for a specific type of equipment. A conformance statement allows "a user to determine which optional components of the DICOM Standard are supported by a particular implementation, and what additional extensions or specializations an implementation adds". All that conformance statements offer is a simple and basic overview of their DICOM capabilities for easy comparison. It will not guarantee whether equipments will work together or not. DICOM Currently used version is ACR/ NEMA 3 (1993) Popularly known as DICOM 3.0 The format is independent of different machines and communication protocols It can be adapted to different medical specialities like radiology, cardiology, pathology, gastroenterology etc DICOM compatibility of imaging modalities CT, MRI, DSA New generation Ultrasound CR, DR or x ray film digitizer Frame grabber for older USG, Fluoroscopy monitor DICOM Viewers There are several DICOM Viewers available both free and proprietary. Some of the DICOM Viewers include: DICOM Works, Osirix, SureVistaVision , UniPACS, Syngo Imaging, VRRender, ImageJ and MicroDicom. Various viewers can connect directly to a PACS server or retrieve images from local storage. HL7 - health level 7 Refers to a worldwide standard for data information systems such as HIS and RIS. It is a less rigorous standard than DICOM. The term Health Level Seven has its origins based on a seven-layer International Organization of Standards (ISO)Communication Model. Each layer has a role wherein layers one to four deal with communication; comprising Physical, Data Link, Network and Transport communication layers. Layers five to seven deal with functions like Session,Presentation and application. The highest level or seventh level is regarded as the application level, which deals with the definition of data to be exchanged. IHE - integrating the health care enterprise The core strategy of Integrating the Healthcare Enterprise(IHE) is integrating radiology workflow within a healthcare setup using existing standards like DICOM and HL7. IHE accomplishes this by a four stage process: a) interoperability problem identification; b) integration profile specification; c) implementation and testing at connectathon and d) integration profile conformance statements HIS and RIS Connection There are at least three and up to five information systems in a radiology department that are required to handle the data associated with an examination These systems include the hospital information system (HIS), the RIS, the PACS, the voice recognition system, and an electronic teaching file system Integration with other information systems and the ability to display relevant data on the desktop are critical for the success of PACS. HOSPITAL INFORMATION SYSTEM (HIS) demographic data of all the patients e.g. patient Stores name, identification number, date of birth Also records admission and discharge dates, outpatient appointments, clinicians responsible for patient care and so forth Other modules of HIS document laboratory data RADIOLOGY INFORMATION SYSTEM (RIS) Can be a stand-alone computer platform, or may be a module of the HIS Stores information specific to the radiology department including radiological reports Modern RIS will incorporate some DICOM features such as modality worklist, modality performed procedure step, interpretation worklist, and structured reporting HIS-RIS-PACS INTEGRATION Preferably bidirectional- 3 main reasons Input of demographic data only once , minimizing human error Anyupdate to a patients demographic data on HIS, RIS, or PACS is propagated to all systems automatically Any scheduling or status data is distributed to all systems automatically, providing advanced notice of events and allowing them to prepare. HIS RIS PACS Twotypes of RIS-HIS integrations are now offered, one type via a broker and another without a broker . The brokerless technology is preferred, as there is less opportunity for data inconsistencies. DATA INTEGRATION Patient demographics entered only once Patient identifier issued and tracked systematically Orders entered only once Performed procedure steps coded – billing automated Image and other exam data stamped with patient and order meta- data Images and other exam data available for viewing anywhere, anytime Persistence of acquired image and exam data Data migration to other vendors patient registers one time Doctor places an order; everyone who needs it gets it Data backups Proprietary data backups are distributed & complicated Scheduled Workflow Profile report report Registration Report report Repository HIS patient Diagnostic Film information Workstation Lightbox images PACS retrieved Orders Placed procedure scheduled Film Image Manager Prefetch any relevant Folder examination orders & Archive prior studies Acquisition modality images Modality worklist stored RIS Orders Filled acquisition completed acquisition Film in-progress completed images printed Modality Benefits of this approach A more cohesive workflow process for transfer of information from HIS to RIS to PACS Smooth, reliable transfer of information between computer systems from different companies Patient journey can be more efficiently and accurately planned Mistakes can be more easily corrected SECURITY weakest aspects of hospital infrastructures is important for radiologists (and all physicians) - aware of the It most frequent security errors that can lead to compromise of patient data. Personalcomputers within the hospital network are particularly vulnerable because of their varied uses User specific log in and password Monitor screen savers Workstation time outs Firewalls PACS- ADVANTAGES No image can be lost or misfiled Easy comparison Simultaneous multilocation viewing Faster image retrieval Computerized data allowing automatic chronological ordering, rapid database search, easy duplication and back up Improved work flow ADVANTAGES Improved throughput and productivity Rapid, remote, and simultaneous access to image data Image postprocessing Cost effectiveness Time saving for non-radiological clinicians Reduced film storage space Introduction of teleradiology over a wide area network PACS- DISADVANTAGES Expensive, technologically complex Absolute dependency of hospital Hospital is no longer equipped to run a film based service Requires dedicated maintenance programme and a carefully devised plan to provide essential clinical services in case of PACS failure Trained hospital staff Vendor provided maintenance service Film System vs. PACS Film System PACS Multiple softcopies Single hardcopy Digital (image database) Analog Automatic & electronic No film loss Manual Simultaneous & immediate Film loss viewing Film storage problem Initial purchasing cost of PACS equipment Maintenance benefits (visible & invisible benefits) Expensive Cost-effective PACS- Issues and Developments REPORTING AND COMMUNICATION Reporting/dictation Macros Structured reporting Speech recognition programme XML- extensible markup language RADIOLOGY SPEECH RECOGNITION SYSTEM most important advance- integration of speech-recognition systems into PACS. If speech recognition and PACS act as a single software system, radiologists can maximize their efficiency the term macro refers to predefined text that may be used instead of or in addition to free-form dictation . Macros improve the efficiency of some speech-recognition systems, particularly when the accuracy of the speech-recognition engine is poor The term voice recognition is frequently used as a synonym for speech recognition Multimedia Reporting Telemedicine “beyond space & time” Teleradiology Medical consultation Telepathology Fetal monitoring Teledermatology Telepresence surgery Telecardiology Quality assurance Telepsychiatry Continuing medical Teleophthalmology education Inevitable Forces to Drive Telemedicine Desire for quality medicine Increasing comfort with technology Globalization of medicine Continued competition Cost-effectiveness Cost-advantage Resouce utilization Focus on marketing orientation Patient satisfaction Outcomes Benefits of Telemedicine Improve patient care Affordable access to experts beyond space and time Expedites decision making Provide economic benefits Save travel time and costs (doctors and patients) Reduce re-examination cost Expedites utilization of human resources and equipment Provide strategic advantage Interchange of physicians’ knowledge and experiences Improve hospital administration Improve quality control and education programs Telemedicine Healthcare Network Rural hospitals Imaging centers Clinics International Medical Center Doctors home health center Complex Emergency center Patient’s home Geriatric facilities 101 Telemedicine - Challenges Creation and adption of standards requirements Technical Clinical protocols Information exchange (data formats, communication protocols, compression) Establish cost-effective in order to secure reimbursement for services Regulatory and medico-legal issues (FDA, patient confidentiality, licensure, etc) Teleradiology PSTN(Modem) ISDN Clinic CT , MRI Image Viewer 512K, 256K Home CR T1, E1 Subpecialist PACS Internet Scanner Server Film Printer Wide Area Network (> 2 km) 103 Questions
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