Positron Emission Tomography (PET) is a method of scanning the body for tumors. It uses a machine capable of detecting gamma rays – a type of radiation – and uses these rays to locate cancerous cells.
When a patient has a PET scan, he or she will be injected with radioactive glucose (a sugar). Glucose injected into the veins will circulate through the body quickly and be absorbed into the cells that need the most energy. Since cancer cells grow faster and demand more nourishment than any other cell in the body, tumors will absorb the majority of the radioactive glucose.
This glucose emits positrons (positive electrons) as the radioactive molecule attached to it breaks down. These positrons collide with electrons in the body. When this happens, a gamma ray is created.
The patient lies down on a table inside a machine that looks a lot like an MRI machine. The PET machine detects the gamma rays and locates the origin of the radiation, thus locating a tumor in the body. This information is used in conjunction with a CT scan or X-ray so that doctors can identify the location of all of the patient’s tumors.
Though a PET scan has very few side effects, the radioactive isotope will stay in your body for 24-48 hours. For this reason, it is recommended that you avoid contact with anyone for a day so that you don’t expose anyone to the radiation.
MRIs, CT scans, X-rays, and gallium scans can also be used to identify and locate tumors.
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