Answer to Question #4756 Submitted to "Ask the Experts"

1. Can you please tell me the difference in a barium enema, an upper GI (gastrointestinal), and an abdominal CT (computerized tomography)? Are the first two just series of x rays and, if so, are they more benign than the CT? Or are they equally risky because of the barium ingestion?
2. I did see the listings on amounts of each and am also confused as to why the abdominal CT is the same amount of radiation as a full-body CT. Could you please explain why?
3. Do I have a higher risk for esophageal cancer because of all these tests in your opinion?

I will group the questions together and hope I give you the information you wanted.

1. The barium enema, upper GI, and abdominal CT all use barium, a contrast material, to help "see" the lining of the digestive tract. These exams all involve the use of x rays. For the first two procedures, the barium enema and upper GI, fluoroscopy is used to visualize the lining and the movement of materials through the GI tract which is otherwise difficult to image or "see" with a simple x-ray exam. They will generally involve more radiation than the abdominal CT. The risk is small from the x rays, and the risk is small from the ingested barium which eventually clears the body.
2. I am not sure which numbers you are comparing for the abdominal CT versus a full-body CT. However, there is a lot of difference between CT scanners such as age, the type of resolution, and the amount of fine detail that is being asked for from the procedure, which all affects the techniques used or the amount of x rays used. Depending on the capabilities of the CT scanner and whether it is being operated to look at fine detail versus a quick overview, i.e., soft tissue structure versus skeletal structure, there is a large variation in exposure. Some examples can be found in an article on our Web site.
3. In my opinion, even if you have a higher risk, it is so small that it cannot be distinguished from your risk due to other environmental or natural variability and the fatal cancer rate of approximately 25% for the population. The Health Physics Society has a position paper that states in part that below 10 rem ". . . risks of health effects are either too small to be observed or are nonexistent," where the rem is a unit that relates to radiation dose. Because the radiation dose from the radiology procedures you received over a period of a few days is less than 10 rem, the risk is so small that it is not reasonable to try to quantify it at these levels. Overall, the risk from these procedures is generally small compared to the medical benefit you were seeking.

Karen S. Langley, MS
Health Physicist