Answer to Question #6162 Submitted to "Ask the Experts"

Q

My son received a CT and I was in the room wearing a lead vest. I was about four or five weeks pregnant, but didn't know about it at the time.

A

First, I hope your son is doing well. When you ask about CT (computerized tomography) exposure, I assume that you are asking about radiation exposure outside of the primary CT x-ray beam, so I will address this area. If you want information on CT scanning operations, see the US Food and Drug Administration Web site.

Returning to your question about CT radiation outside of the primary x-ray beam, this radiation is of much lower intensity than the primary x-ray beam used to image the patient. Essentially, it is scattering as light would be from the patient and objects such as the patient's table and components inside of the "donut." As with typical diagnostic x-ray exams, individuals are usually not allowed in rooms during the exams, but I assume that you were allowed in order to provide comfort to your son.

While the scattered radiation may be 1/1,000 or less of the primary beam, you were given a leaded vest to further reduce your exposure to the radiation. This is the same type of apparel that x-ray technologists use during fluoroscopic x-ray procedures and they need to be in the x-ray room. The effectiveness of leaded aprons and vests have been considered in other "Ask the Experts" questions—ATE 2827 and ATE 4115.

John P. Jacobus, MS
Certified Health Physicist