Answer to Question #10970 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:


Thank you for taking the time to read this as I am very concerned for my future. Recently, I received my first brain CT (computerized tomography) scan after a car accident; it was normal. About a year later I got another concussion and received another brain CT scan; it was normal, too. Several years later, I got another concussion and received two brain CT scans in one weekend, both normal. Yesterday I had to go to the ER (emergency room) for a severe headache and eye pain and they gave me a brain CT scan and a sinus CT scan.

I am a 25-year-old female and I am nervous for the future because of the six CT scans in four years with four of them eight months apart. On top of that I have received x rays for the concussions to rule out skull fractures and dental x rays for dental work. I also worked with a cardiologist who used fluoroscopy for procedures for six months but I was only involved with procedures between once every week to two weeks. Am I at very high risk in my future?


Please allow me to make some statements to help put your radiation exposure in perspective. The average American is exposed to approximately 3 mSv of radiation annually from “natural background radiation” that you encounter just from living each year.1 Some of this radiation comes from space and some from naturally occurring radioactive forms of water and minerals. You have had six medically prescribed head CTs to rule out medical issues over the past four to five years. Using just national averages, the radiation dose that you could have received from all of your CT exams would be approximately 12 mSv (six times 2 mSv).2 Just as a reference, people who work with radiation in the hospital may receive up to 5 mSv each year as part of their occupational dose. 

The Health Physics Society and the American Association of Physicists in Medicine have both issued position statements that state essentially that:

“Risks of medical imaging at effective doses below 50 mSv for single procedures or 100 mSv for multiple procedures over short time periods are too low to be detectable and may be nonexistent.”3,4

Since you have indicated that you have had concussions and symptoms that might indicate a serious medical condition, your physician thought it was necessary that you receive these CT scans to rule out medical issues. It is within your rights to question any medical test to make certain that it is necessary. It is also very important that you seriously consider the advice of your physician when exams of any kind are ordered. However, the risk of your CT tests is very, very small compared to the very important information that these exams gave your physician regarding your health.

Steven H. King, CHP, DABMP


1 (see Risk: Radiation Exposure from Medical Exams and Procedures)
2 (see Background Radiation Fact Sheet)
3 (see Risk: Radiation Risk in Perspective)

Answer posted on 18 June 2014. 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.