What the risks are:

CT scans and other x-rays are regulated to provide the minimum amount of radiation exposure needed to produce the image. During pregnancy, a thoracic CT scan is not recommended unless the benefits outweigh the risk of radiation exposure to the fetus. CT scans provide low levels of radiation.

The most common dye used is iodine-based. A person who is allergic to iodine may experience nausea, vomiting, sneezing, itching, or hives, and occasionally anaphylaxis (life-threatening allergic response). In people with kidney problems, the dye may have toxic effects on the kidneys.

Special considerations:

The benefits of a CT scan usually far outweigh the risks. A CT scan is one of the best ways of looking at soft tissues such as the heart and lungs.