Cardiac computed tomography (to-MOG-rah-fee), or cardiac CT, is a painless test that uses an x-ray machine to take clear, detailed pictures of the heart.
This common test is used to look for problems in the heart.
During a cardiac CT scan, an x-ray machine will move around your body in a circle. The machine will take a picture of each part of your heart. A computer will put the pictures together to make a three-dimensional (3D) picture of the whole heart.
Sometimes an iodine-based dye (contrast dye) is injected into one of your veins during the scan. The contrast dye travels through your blood vessels, which helps highlight them on the x-ray pictures.
Because an x-ray machine is used, cardiac CT involves radiation. Although the amount of radiation used is considered small, it's similar to the amount of radiation you're naturally exposed to over a 3-year period.
There's a small chance that cardiac CT will cause cancer because of the radiation involved. The risk is higher for people younger than 40 years old, especially children. However, new cardiac CT methods are available that reduce the amount of radiation used for this test.