Answer to Question #15054 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

I'm a 40-year-old female with some elevated cholesterol levels. I was thinking of asking my doctor for a noninvasive computed tomography coronary angiogram (CTCA). My research indicated the dose from the procedure could be as high as 16 mSv. Reading some literature on the topic it seems there is a risk of DNA cell death as well as slight increase to breast and lung cancer for women. The HPS website suggests there is no risk. I am confused. Can you help me understand?

A

Your question is one of great interest to many patients. Below dose levels of 100 mSv, approximately six times the dose of your prospective computed tomographic coronary angiography (CTCA), there is considerable debate of what, if any, expected risk there is from radiation exposure. Many reference documents, including the National Academies' Report on Biological Effects of Ionizing Radiation VII (BEIR VII), support the concept of the linear no-threshold (LNT) model for radiation exposure. The LNL model suggests that any amount of radiation exposure carries some risk, even if it is extremely small. Some clinical studies for imaging procedures, such as ones by Faletra et al and another by Sodickson et al., suggest that low levels of risk may exist for CT procedures, especially for younger women due to breast cancer concerns.

Radiation risk estimates vary amongst the literature, but it is often extremely low and sometimes found not to be statistically above zero. The website X-rayrisk.com, which uses the BEIR VII model, estimates a population-based potential excess risk of cancer of 0.13% for an average 45-year-old female receiving a CTCA. It is important to note that these risks are developed for the population as a whole and don't predict a single individual's risk. These minimal, but non-zero, potential risks from the CTCA are usually outweighed by the advantages and knowledge gained from the procedure itself. In your example, you would get reassurance about your risks of coronary heart disease and may find out changes you need to make for your own health. Skipping the procedure due to potential radiation risks may lead to missing out on that vital information.

Something you have already mentioned is likely your best option moving forward: speaking openly with your doctor about the situation. If together you believe a CTCA is the best method for monitoring your situation, then the benefit you would gain from the procedure outweighs any small risk that may be present. If there are other lower, or zero, radiation procedures that may replace the CTCA for similar clinical knowledge, you may wish to explore those options with your health care professional as well.

Brian Serencsits, MS, CHP

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
Answer posted on 13 September 2023. 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.