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The different varieties of PET cancer scans are differentiated by which type of radioactive material is used. This radioactive tracer is chosen based on which area of the body is under investigation. The most commonly used radiotracer in PET cancer scans is 2-Deoxy-2-[18F]fluoro-D-glucose, sometimes called 18F-FDG for short, which is a form of sugar with a radioactive tag. Dozens of other kinds of radioactive substances are currently available for use in PET cancer scans with humans. The appropriate radiotracer for a particular scan will be chosen by experts in nuclear medicine and medical imaging.
PET cancer scans are technically known as positron emission tomography, a type of advanced medical imaging that can show the functioning level of human organs and tissues. PET scans use a low dose of radioactive material that is injected, swallowed, or inhaled by the patient. The radiotracer tends to accumulate in areas of greater metabolic activity, such as cancerous tumors, which emit gamma rays and show up on the scan image as visual hot spots. Unlike other types of medical imaging, a PET scan can detect subtle differences in metabolic activity with 95% accuracy, leading to the ability to distinguish between benign and malignant cancer tumors.
A PET scan might be used to assess a number of medical conditions, including cancer, heart problems, and neurological issues. PET cancer scans are often used to monitor the progress of cancer and help assess the effectiveness of treatment. Some kinds of cancer are unlikely to show up on a PET scan, which is generally used for specific types of cancer affecting the lungs, breasts, cervix, brain, thyroid, or esophagus. PET scans are also typically used with melanoma and lymphoma.
A PET scanner is a large box-shaped machine with a tunnel area in the middle. The patient lies on an exam table that slides slowly into the tunnel space. Some individuals might experience anxiety during the exam due to being enclosed in a confined space. For many people, the only discomfort involved in the procedure is a result of having to stay very still for about 30 minutes during the scan. The PET scan procedure is considered non-invasive and painless.
The small amount of radiation used in a PET scan has a very short half-life, meaning it will break down within about two hours and pass out of the body through urination within one to two days. This procedure is not recommended for pregnant or breastfeeding women due to the danger of exposing the fetus or infant to radiation. There is also a slight risk of allergic reaction to the radiotracer used for the procedure.