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What is a PET Scan?
A PET scan is a diagnostic tool used to image the body. PET stands for Positron Emission Tomography. It images the emissions given off by a radioactive tracer that is injected into the body. It has a number of applications including detecting cancer, evaluating how well cancer treatments are working and viewing how the brain or heart is functioning.
The PET scanner is a large machine with a round opening in the center. Inside, there are several detectors that react to the radioactivity from the tracer. The detectors pick up gamma rays emitted from the tracer. A workstation in an adjacent room is where the technologist operates the PET scan and processes the data.
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Detecting Bone Cancer
There are several types of bone cancers that can be detected with a PET Scan. Primary bone cancer is rare. It is more likely that a PET scan is used to detect cancers of the bone that originated elsewhere in the body. Usually, the imaging test is done to see if a cancer has spread to the bone.
To detect bone cancer with a PET scan, radioactive glucose is used as the tracer. Cancer cells require much more glucose than normal cells. As a result, the radioactive glucose will accumulate in the cancer cells and emit much more radiation. The detectors will image the body and areas with cancer cells will stand out.
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A PET scan for cancer may take 30 minutes to complete, and expect another 60 minutes of prep time to allow the radioactive glucose to circulate through the body. An IV is set up, usually in the arm, and the radioactive glucose is injected. A contrast material may be given with a glass of water to improve the imaging. When you are ready to be scanned, you lie on your back on the table, as the technologist operates the PET scan. The table moves into the circular opening of the scanner and the scanning starts. Afterwards, the IV is removed and the images are examined by your doctor.
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A PET scan for cancer is relatively safe, but there are a few concerns. Exposure to low doses of radiation is one risk associated with this test. Pregnant women and those that are breastfeeding should consult their doctor about the possible risks. Over time, the tracer will lose its radioactivity through the process of radioactive decay. It will also pass through the urine. It is important to wash your hands thoroughly afterwards to avoid contamination.
In some individuals, the radioactive material may cause an allergic reaction. It is usually mild and involves a skin rash. The injection site may become red or swollen. Those that are claustrophobic may feel uncomfortable during the scanning procedure.
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1. "Bone Cancer: Questions and Answers." National Cancer Institute. http://www.cancer.gov/cancertopics/factsheet/Sites-Types/bone
2. "Positron Emission Tomography – Computed Tomography (PET/CT)." Radiological Society of North America http://www.radiologyinfo.org/en/info.cfm?pg=PET
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