Nuclear Medicine Imaging and the treatment of Cancer Gamma photons are the most energetic photons in the electromagnetic spectrum. Gamma rays (gamma photons) are emitted from the nucleus of some unstable (radioactive) atoms. Gamma Radiation What are the Gamma radiation is properties of gamma very high-energy radiation? ionizing radiation. Gamma photons have no mass and no electrical charge--they are pure electromagnetic energy. Gamma Radiation Because of their high energy, gamma photons travel at the speed of light and can cover hundreds to thousands of meters in air before spending their energy. They can pass through many kinds of materials, including human tissue Gamma Radiation What is the difference between gamma rays and x-rays? Gamma rays and x-rays, like visible, infrared, and ultraviolet light, are part of the electromagnetic spectrum. While gamma rays and x-rays differ in their origin. Gamma rays originate in the nucleus. X-rays originate in the electron fields surrounding the nucleus. Gamma Radiation How do we use gamma emitters? The penetrating power of gamma photons has many applications. Gamma rays penetrate many materials, they do not make them radioactive. The three radionuclides by far most useful are cobalt-60 and cesium-137 and technetium-99m. Gamma Radiation Uses of Cesium-137: cancer treatment Uses of Cobalt-60: sterilize medical equipment in hospitals treat cancer Gamma Radiation Uses of Technetium-99m: TC-99m is the most widely used radioactive isotope for diagnostic studies. (Technetium-99m is a shorter half-life version of technetium-99.) Different chemical forms are used for brain, bone, liver, spleen and kidney imaging and also for blood flow studies. Radioactive Measurements 1. Competitive Binding Assays 2. Time Dependent Measurements 3. Radio Nucleotide Imaging Gamma Camera – scintillation camera 4. Tomography SPECT imaging PET imaging 1. Competitive Binding Assays No radioactive substance is given to the patient Blood from a patient is mixed with a radioactive substance in the laboratory Radioimmunoassay Thyroid Hormone and Iron Binding Sites most common. 1. Competitive Binding Assays 2. Time Dependent Measurements Radioactive Tracers are to the patient administered. Allows the volume of a compartment to be measured. Intravenous Pyelogram An Intravenous Pyelogram (IVP) is an x-ray examination of the kidneys, ureters, and urinary bladder. Intravenous Pyelogram HIDA Scan This is a test done to diagnose obstruction of the bile ducts (for example, by a gallstone or a tumor), disease of the gallbladder, and bile leaks. Cardiac Angiography Coronary angiography is performed to detect obstruction in the coronary arteries of the heart. During the procedure a catheter is inserted into an artery in your groin and then threaded carefully into the heart. The blood vessels of the heart are then studied by injection of contrast media through the catheter. A rapid succession of X-rays is taken to view blood flow. The arrow indicates a blockage in the right coronary artery. Cerebral Angiogram This image taken before angioplasty: This patient had episodes of weakness, leading to the angiogram. The angiogram shows a very narrowed artery supplying the right side of brain. This vessel is within the skull on the surface of the brain Cerebral angiogram taken after angioplasty: The narrowing is less severe and the branches beyond the narrowing fill better 3. Radionucleotide Imaging Image is generated using radioactive decay from an organ Usually a function of time. Provide functional information 3. Radionucleotide Imaging Single detectors are used for thyroid studies. 3. Radionucleotide Imaging Scintillation Camera Shows two dimensional data Studies physiologic function Ventilation-Perfusion Scan of a lung looking for a blood clot. A bone scan is used to find bone problems, such as cancer, infections, or fractures, to check joint replacements, and to find joint problems, such as arthritis. A small amount of injected radioactive matter (tracer) and a camera to form an image. Bone scan looking for metastatic bone cancer. Looking for fibrous dysplasia that is a congenital, non- hereditary skeletal disorder Patients are often asymptomatic. Others experience pain, pathologic fractures and bone deformity Imaging of Acute Osteomyelitis in the Diabetic Foot A 65 year old male with a history of non-insulin dependent diabetes mellitus, alcohol abuse, and severe peripheral vascular disease presented with a non- healing ulcer of the left first toe. This Indium White Blood Cell Scan demonstrates areas of infection in the abdomen after surgery for colon cancer. 4. Tomography The fourth class of imaging is the tomographic reconstruction of body slices. Single-photon emission computer tomography - SPECT scan Position Emission Tomography – PET scan SPECT SCANNER SPECT Imaging The use of a brain SPECT scan is based on the principal of blood flow. Areas of increased blood flow take up more Radioactive tracer than areas of less blood flow. Blood flow in the brain is directly related to brain activity. COMMON DISEASES EVALATED BY SPECT Attention Deficit Hyperactive Disorder Autism, Aspergers syndrome Unipolar and Bipolar Depression Anxiety states - Panic, Obsessive-Compulsive Disorder Epilepsy and Non-epileptic seizure equivalents Post Traumatic Stress Disorder Migraine and common headaches Schizophrenia Dementia and memory loss- Stroke- Multiple Sclerosis- Parkinson's Disease SPECT Image Blood flow to the brain is represented on a color scale, dark areas have no flow and bright yellow areas have good blood flow. The dark "butterfly- shaped" area in the center of the brain is normal, but the dark area on the right of each picture is the region of impaired blood supply (ischemia) that corresponds to the patient's acute stroke. Prior to t-PA, the SPECT scan showed a large area of the brain that has lost its blood supply (arrow). Several hours after treatment with t-PA, the blood flow has dramatically improved, although there is still a small area ischemia (arrow). PET Scanner Image of heart which has Normal PET scan of a had a mycardial infarction. heart. The arrow points to "dead" myocardial tissue. Therefore, the patient will not benefit from heart surgery, but may have other forms of treatment prescribed. PET image of same patient PET image showing malignant with enlarged left axillary breast mass that was not lymph nodes (indicated by revealed by conventional arrows), which through biopsy imaging techniques such as were found to be metastatic. CT, MRI, and mammogram The whole body scan reveals a mass in the left breast (indicated by arrow), that was malignant and subsequently removed Normal Brain Image of the brain of a 9 year old female with a history of seizures poorly controlled by medication. PET imaging identifies the area (indicated by the arrows) of the brain responsible for the seizures. Through surgical removal of this area of the brain, the patient is rendered "seizure- free". PET measurements of cerebral blood flow (CBF) and oxygen extraction by the brain (OEF) before (top row)and after (bottom row) angioplasty of a focal severe stenosis of an artery at the base of the brain (supraclinoid internal carotid artery). 65 year old male with brain tumors imaged here with a PET scan. Treatment of Cancer Radioactivity is very effective in the treatment of certain cancers. The choice is basically do you administer the radiotherapy externally or internally. External Beam Therapy External beam therapy (EBT) is a method for delivering a beam of high-energy x-rays to the location of the patient's tumor. The beam is generated outside the patient and is targeted at the tumor site. These x-rays can destroy the cancer cells and careful treatment planning allows the surrounding normal tissues to be spared. These cancers are commonly treated. Breast Cancer Colorectal Cancer (Bowel Cancer) Head and Neck Cancer Lung Cancer Prostate Cancer High Energy X-Rays Linear Particle Accelerator Zapping Cancer Proton Beam Therapy Proves Effective in Targeting Tumors Aug. 17, 2004 — A new kind of radiation is proving effective in the fight against cancer. Proton beam therapy, according to doctors, zeroes in on tumors with impressive results and without the devastating side effects of traditional radiation therapy. "We can shape the beam more accurately, hitting targets with more precision," said Dr. Jerry Slater, clinical director of Loma Linda's Proton Therapy Center in Southern California. "You don't feel any pain," said Ron Leuck, who is being treated for prostate cancer with the new therapy. During the treatment, a rotating scaffold three stories high aims computerized ray guns directly at his tumor. . Proton Beam Radiotherapy This form of external beam irradiation involves directing radiation through the front of the eye in order to reach the intraocular tumor. When compared to low- energy eye-plaque radiation therapy, It is easier to treat tumors that are surrounding the optic nerve with protons. Brachytherapy Brachytherapy is where radioactive seeds or sources are placed in or near the tumor itself, giving a high radiation dose to the tumor while reducing the radiation exposure in the surrounding healthy tissues. The term "brachy" is Greek for short distance. Brachytherapy Brachytherapy is not new. Throughout this century, several types and routes of implantation of radioactive seeds have been used to treat cancer. Radioactive Iodine seeds were widely used during the 1970s and 1980s. Brachytherapy sources can be divided into permanent and temporary groups. Permanent sources tend to have lower energy and shorter half-lives. The advantage of these lower energies is enhanced safety. The disadvantage is that anatomical adjustments cannot be made once the sources are placed. Currently, temporary implants consist primarily of 192Ir and 137Cs. Currently, the 2 most common permanent radioactive sources for brachytherapy seeds are 125I and 103Pd. The lower the energy emitted by the photons, the higher the energy transfer. The higher the energy transfer, the higher the radiobiologic effect, which can lead to lower total doses. Prostate Cancer The prostate gland is Cancer is common. just beneath the male bladder. The prostate gland can be felt with a digital rectal exam, Cancer is sometimes detected this way. 67 year old male with metastatic prostate cancer. Iridium 192 is used for high–dose rate treatment of prostate cancer. During the implantation, hollow needles are inserted transperineally. The needles are then connected to an automated remote- controlled loading machine. The total irradiation time is usually only 5-10 minutes. Temporary seed placement is shown here.
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