Difference Between
a PET & CAT Scan
PET scans and CT (or CAT) scans are imaging tests that produce pictures of your internal organs. While both tests utilize radiation to capture images, they do so in very different ways.
X-Rays
According to MedlinePlus, CT scans use X-rays to create images. While the CT scanner aims X-rays at your body, detectors inside the scanner monitor the amount of X-rays that make it through your body and use this information to produce images.
Radiotracer
As the Mayo Clinic notes, instead of X-rays, a PET scan uses a radiotracer, a small amount of radioactive material injected into your body before the scan. As it is absorbed by your organs, the radiotracer becomes concentrated in areas with higher chemical activity, which show up as bright spots on the PET scan.
Detection Time Frame
According to the Cleveland Clinic, a PET scan often detects disease earlier than a CT scan. While a CT shows structural changes in organs or tissues, a PET scan displays the cellular-level metabolic changes that are often the first signs of disease.
Risks
According to the Mayo Clinic, except in the case of pregnant women, radiation exposure during a PET scan is too low to pose a risk. Radiation exposure during a CT scan, however, potentially raises your lifetime risk of developing cancer.
Uses
As the Mayo Clinic explains, PET scans are most often used in diagnosing and treating heart disease, cancer, and neurological disorders. CT uses include cancer and heart disease as well as additional applications such as examining infections and injuries and diagnosing muscle or bone problems.
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