Answer to Question #14888 Submitted to "Ask the Experts"

My daughter is under five years old. Over a year ago, she had one set of x rays on her leg (three images ankle-hip). Several weeks ago, she had three images taken of one of her hands. At the time, I did not have a clear understanding of how damaging this radiation could be. Though I questioned both instances, I feel I placed too much trust in the physicians. My daughter's leg x rays were taken at a pediatric medical center. Her hand x rays took place at an emergency room. The x-ray technologist told me they used a pediatric dose of radiation. I requested only one image of her hand, but the x-ray technologist insisted they never take only one and took three. I feel very guilty for not standing up for my daughter and preventing these unnecessary doses of ionizing radiation.

What is the pediatric dose (mSv) of radiation from these x rays? Does the fact that three images were taken compound the radiation damage to the area? What are the pediatric equivalents to radiation we encounter every day? What are some of the best ways to reduce her exposure to harmful radiation moving forward?

I am sorry your child had to have x rays, but I want to begin by reassuring you that the dose from these exams is extremely low and the risk of developing cancer is the same as it was without the x rays. Modern x-ray systems and techniques that have been optimized for children have made the radiation doses much lower than in the past.

For x-ray exams, it is normal to take two or three images from different directions so the physician can see all of the bones and joints clearly. The effective dose in mSv is determined based on the parts of the body that were exposed to radiation and how sensitive they are. The arms, hands, legs, and feet are not very sensitive to radiation. In addition, they are not very thick, so the amount of radiation needed for the x-ray images is very low. For these reasons, the estimated effective doses from x-rays of the legs and hands are each less than 0.001 mSv. The effective dose for a pelvis and hip x ray is approximately 0.1 mSv for a child between one and five years old. As noted in the Health Physics Society's position on Radiation Risk in Perspective, for effective radiation doses below 100 mSv, the health risks are too small to be seen or do not exist. To put the doses in perspective, the average dose from natural background radiation in the United States is about 3 mSv per year and the annual occupational dose limit is 50 mSv per year.

Your daughter wasn't harmed by the x rays she received, and her doctors obtained information they needed to ensure an accurate diagnosis and proper treatment. When x-ray and CT imaging is medically necessary, the benefits outweigh the very low theoretical risks from the radiation. I recommend discussing your concerns with your daughter's doctors if imaging tests are needed in the future. The doctor should be able to explain the reason for the imaging test, whether there are alternatives, and the risks and benefits of the imaging test.

Please don't worry about the radiation that was used during these x rays. The dose is extremely low and there was a benefit to having the information from the exam to diagnose and treat your child.

Deirdre H. Elder, MS, CHP, CMLSO