Answer to Question #10655 Submitted to "Ask the Experts"

Category: Medical and Dental Patient Issues — Diagnostic X Ray and CT

The following question was answered by an expert in the appropriate field:

Q

My son was six months old and had GERD (gastroesophageal reflux disease). He became dehydrated and we took him to the hospital. He had two upper GI (gastrointestinal) series done within three days. I would like to know how much this increases his chances of having a medical problem or cancer from the increased exposure to radiation. My son is now 2½ years old. Do repercussions decrease as he gets older? In other words, does radiation dispel out of the body over time? If so, then why is a person's lifetime exposure considered? I understand what has been done is done but I am his mom and he is my only child so, of course, I have my concerns. Thank you in advance for your time and consideration.

A

Your concern as a parent is understandable, but in this case you can rest easy in that there is little, if any, risk of medical problems associated with the x-ray procedure. A pediatric upper GI exam such as your son received typically results in an effective radiation dose of approximately 3 mSv. The "normal" or existing risk of fatal cancer over a lifetime is 20 percent for U.S. adults. In other words, approximately 20 percent of us will die of cancer from all causes. The estimate for an effective dose of 3 mSv is approximately an extra 0.01 percent risk of fatal cancer over a lifetime, or roughly one in one hundredth of a percent. This means that if everyone was exposed to an additional 3 mSv, the fatal cancer rate would go from 20 percent to 20.01 percent.

Another way to look at this risk is to point out that 3 mSv is the effective radiation dose that a typical individual experiences per year from all sources of natural background radiation. This is, of course, a population average and it varies for individuals by as much as a factor of five or so depending upon where they live and what they do in a given year. No peer-reviewed scientific study has linked background radiation level differences as experienced by individuals in the United States with differences in cancer risk. Therefore, the risk from this exam is considered to be so small as to be theoretical rather than a cause for concern. On a personal note, both of my children received imaging studies involving x rays prior to the age of 13 for different reasons. In both cases, I was confident that the negligible and largely theoretical risk from the x rays was far outweighed by the very real medical benefit.
 
You mentioned consideration of the age of the patient when calculating risk. This is an area of current research interest. Atomic bomb survivors from Hiroshima and Nagasaki who were young children at the time of their exposure, who are now in their 60s, are being studied. Also being studied are patients who had extensive imaging studies in pediatric populations many years ago, such as spinal exams for scoliosis. These studies are revealing that radiation-produced cancer in later years is MORE likely for exposure during childhood than for exposure as adults. Although the risk is still small, medical professionals of all specialties are aware of this and are working to ensure that the lowest radiation doses necessary to obtain useful images are employed and that exams are only carried out when medically necessary. I suggest that you visit the Image Gently website to find detailed information for the general public as well as for medical specialists. All of the major x-ray equipment vendors now provide special low-dose settings for equipment used for pediatric patients to ensure that radiation dose is as low as is reasonably achievable.  
 
Perhaps one day it will be possible to image the interior of the human body without ionizing radiation, such as x rays. Many imaging procedures may be carried out with ultrasound and magnetic resonance imaging, neither of which use ionizing radiation and both of which are thought to have no biological effects. For now, there are some studies that are best done with x rays. A good analogy is with invasive versus noninvasive surgery. More and more, surgery may be carried out with minimal incisions using flexible probes that allow TV cameras or even surgical tools to be inserted into openings that are only an inch or so wide. But not all surgeries may be performed this way. Someday both imaging and surgery may be safer and less disruptive to the human body. However, they will never be totally without risk. Nothing that we do in medicine is without risk. The goal is to minimize the risk while increasing the efficacy of imaging, surgery, or whatever is being done for the patient.

E. Russel Ritenour, PhD, DABR

Answer posted on 12 June 2013. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.