Answer to Question #718 Submitted to "Ask the Experts"

Dr. Eric J. Hall, Professor of Radiation Oncology and Radiology, College of Physicians and Surgeons, Columbia University, says this about the safety of radiation doses encountered in diagnostic radiology: "There is no direct evidence that the small doses of radiation, similar to those used in diagnostic radiology, cause harmful effects in the persons who are exposed" (Hall 1984).

The question posed is a difficult one for a health physicist because we like to know how much radiation is associated with a particular procedure before answering the question. In the case of diagnostic radiation for a two-month-old infant, the data are scant. The National Council on Radiation Protection and Measurements (NCRP) (NCRP 1989) cites estimates of radiation dose for an ADULT for a barium enema and abdominal spot film of 900 and 200 mrad, respectively. The dose for an infant would be much less. In fact, we would expect the dose to be far less than the 10 (10,000 mrad) level at which increased risk has been observed in studies of human populations.

The risks associated with radiation derive from studies of populations, like the survivors of the atomic bombings of Hiroshima and Nagasaki during WWII. Effects such as cancer have been observed in persons who received doses well above those associated with typical medical procedures and estimates of risk are estimates that have been scaled down to doses associated with medical procedures. These estimates indicate that the risks, if any, are very small. Moreover, we can say with confidence that no immediate effects have been observed in the young at doses of less than 10 rad delivered to the whole body.

In conclusion, individuals are well advised to seek medical care and the benefit of diagnostic x-ray procedures so that illnesses may be diagnosed and treatment sought; when the diagnosis shows that the suspected illness is not present, comfort can be gained from the peace of mind that is derived from this knowledge and the avoidance of potentially risky medical procedures.

Further helpful information on understanding radiation is available on Dr. Eric Hall's Radiation and Life Web site as well as at many other sites recommended in other answers on Ask the Experts. NCRP reports can be ordered from the NCRP Web site.

References

• Hall, Eric J. Radiobiology for the radiologist. J.R. Lippincott; 1984:422.  
• National Council on Radiation Protection and Measurements. Exposure of the U.S. population from diagnostic medical radiation. Bethesda, MD: NCRP; NCRP Report No. 100; 1989.

Roger W. Broseus, PhD, Certified Health Physicist