A PET scan or a PET CT Scan is used to check diseases in the body. PET Scan can detect how you're your organs and tissues are working. A small amount of a radioactive substance is injected into a vein. This substance under the PET Scan machine can look at the blood flow, oxygen use and metabolism in your body at the cellular level. The amount of radioactive substance is quite low and hence is not considered harmful.
A CT scan provides detailed pictures of tissues and organs inside the body, while a PET scan reveals any abnormal activity that might be going on there, combining these scans creates a more complete image than either test can offer alone.
During a PET scan a patient is exposed to radiation from the X-rays and the radioactive drug. The radiation in the radioactive tracer is very small, and goes away (decays) very quickly. This is generally considered as not harmful to the body. However, pregnant women are generally advised not have a PET Scan as the impact of its radiation on foetus is not known.
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