Answer to Question #5683 Submitted to "Ask the Experts"

Q

Recently I had my first colonoscopy. When the doctor couldn't see the end of the intestine, he ordered a barium enema. I received 10 x rays to my lower abdomen. There was no lead shield used for my chest. When I expressed concern to the technicians about so many x rays, they said, "Oh, they're low dose." Having 10 x rays of my abdomen, without any shield, worries me. Can you explain what "low dose" means, exactly, and how many "regular" x rays it would be equivalent to? I am not x-ray phobic, but 10 at one time seems like excessive exposure to me.

A

It is understandable that 10 x rays sounds like a high number, but it is pretty routine for a barium enema to have between 10 and 20 standard x rays taken along with some fluoroscopy to see the barium actually moving live-time.

The Health Physics Society's Public Information Committee just released a fact sheet listing common x-ray procedures and the radiation dose associated with them. In it, there is a line item for a barium enema with 10 images and a couple of minutes of fluoroscopy. The effective radiation dose is listed as 700 mrem.

You can put this dose in perspective by looking at the other medical exams listed along with their associated radiation doses. I can also add a few things: the average annual effective radiation dose to all individuals from natural background radiation is 360 mrem, workers who are exposed to radiation as a part of their jobs are allowed to receive up to 5,000 mrem annually, the lowest effective dose shown to cause a clinically observable biological effect (changes in the blood) is about 20,000 mrem.

Ten x rays does sound like a lot. The radiation dose from a barium enema, however, is actually relatively small.

Kelly Classic
Certified Medical Health Physicist