In the gantry, there’s a series of small x-ray sensors which rotate. They take multiple x-ray pictures from various angles. Computers interpret the data, compiling the many images obtained. The images appear as cross-sectional slices obtained at many levels.
A small amount of a radioactive isotope is administered to the patient – injected intravenously, inhaled or swallowed. These isotopes attach themselves to certain molecules in the body. Images are obtained to determine the abnormality.