Answer to Question #1977 Submitted to "Ask the Experts"

The number of films for these tests can vary significantly, especially if something unusual is seen on the films or during fluoroscopy. One reference in the literature, which includes 5,000 patient dose measurements from 375 hospitals, indicates that for the barium swallow, 24 images and 106 seconds of fluoroscopy are used on average (Wall and Hart 1997). This reference suggests that for the small bowel follow-through, four images and another 78 seconds of fluoroscopy are used. Combined, the effective radiation dose for this procedure is about 0.45 rem (4.5 mSv). Risk at this level, if any, is very small. According to Dr. Eric Hall, a radiation biologist, "there is no direct evidence that small doses of radiation, similar to those received in diagnostic radiology, cause harmful effects in the persons who are exposed" (Hall 1994). As a comparison, we are all exposed to naturally occurring radiation—what we refer to as "natural background." Each year, we each receive about 0.36 rem (3.6 mSv) from background radiation exposure.

Kelly Classic
Certified Medical Health Physicist

References:

• Wall BF, Hart D. Revised radiation doses for typical x-ray examinations. British Journal of Radiology 70:437-439; 1997.
   
• Hall EJ, Radiobiology for the radiologist. Fourth Edition, J.R. Lippincott; 1994.

Editor's Note: Very good discussions on the risk from medical exposures can be found under "Risk/Benefit of Medical Radiation Exposures" and "Benefits of Medical Radiation Exposures" in the "Ask the Experts" section of the Health Physics Society's Web site.