Positron Emission Tomography (Pet Scan)

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If your doctor ever refers you for a PET scan, you will be introduced to a fairly new medical imaging technique. Since this emerging modality is so new, a lot of the general public is not aware of what a PET scan exactly is. This essay will help explain the concept of this modality and the characteristics of it that allow doctors to diagnose and manage the proper care for some of today's most devastating medical conditions known to man. Positron emission tomography, also called PET imaging or a PET scan, is a diagnostic examination that uses positively charged particles. The particles are radioactive positrons that detect changes in the body's metabolism and chemical activities. Positrons are tiny particles emitted from a radioactive substance administered to the patient which helps provides a color-coded image of the body's function, rather than its structure. During a PET scan, a substance called a tracer that produces radioactive positrons either is injected into a vein or inhaled as a gas. The radioactive substance is produced in a machine called a cyclotron and attached to a natural body compound. The most common body compound that the positrons are attached to is glucose. Other natural body compounds commonly used to attach the radioactive substances are carbon, nitrogen, oxygen and ammonia. The compounds become altered to allow them to emit positrons. Once the tracer enters the body it will take approximately 30 to 90 minutes for the substance to travel to a specific target organ, such as the brain or heart. During this time, you will be asked to rest quietly and avoid significant movement or talking, which may alter the way the substance localizes in a certain tissue. There the tracer emits positrons, which collide with electrons to produce gamma rays. These gamma rays are detected by a ring-shaped PET scanner and analyzed by a computer to form an image of the target organ's metabolism or other functions. Different colors or degrees of brightness on a...
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