Answer to Question #15171 Submitted to "Ask the Experts"

Category: Medical and Dental Patient Issues

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

Q

I've had a terrible year. I have had some medical issues that resulted in the doctors prescribing many radiation procedures. The procedures included two hepatobiliary iminodiacetic acid (HIDA) scans, 11 computed tomography (CT) scans (three head neck, one chest, seven abdominal/pelvic), two mammograms, six chest x rays, and a few dental x rays. The first set of procedures were all performed within a month. The other procedures were spaced out over the next 11 months. From my CT scans alone, I believe I have been exposed to at least 65 mSv which is well over the 50 mSv dose limit for radiation workers.

I am severely depressed over this. The doctors do not seem to care when I express concern and try to explain why I can't have the procedures. Some say, "You're already at a high risk." Some say, "Just don't get anymore" as they are clicking the order button. Some have told me I don't have to worry.

Because of my health issues, I am sure I will need more radiation procedures in the future. What does my risk look like from here on out? I'm terrified.

A

I am sorry to hear that you have had such a difficult year. It sounds as though you have been unable to get useful information from your doctors, which must be incredibly frustrating. I hope I can answer your questions.

The overall goal in medical imaging is for the benefit from the information in the images to be much higher than any associated risk from the radiation used in the exam. We know a great deal about how large doses of radiation affect the body. There are still things we do not know for certain about exposure to small doses of radiation, like those used in x ray, CT, mammography, and dental x rays. But what we do know is that the risk from single doses below 100 mSv is very small and may even be zero. People have studied the effects of radiation for many decades, and any effect from these low doses is so small that it is not clear that there is any risk, even after studying hundreds of thousands of people. There is also no evidence that the risk of having multiple scans spread out over time increases your risk of developing cancer. Human cells have repair mechanisms that are constantly working, and these get kicked into "high gear" after exposure to even small amounts of radiation. It takes about 24 hours for those cells to repair any damage. So, about a day (hours after your scan), those repair processes have already finished. If you have another imaging study, your body has already "reset," so to speak, so your risk from that second scan is no higher than it was for the first scan.

You mentioned dose limits for radiation workers. Dose limits are used for radiation workers because they are not getting any benefit from that radiation exposure but are being paid for assuming that small risk in their work. When someone has a medical imaging exam, there is a benefit to having that exam. The information from the images is used to help guide your medical care. If the images were used to help you and your doctor make decisions about your medical care the benefit is likely much, much higher than any risk from the radiation exposure.

Each x ray, CT, and mammogram should be clinically indicated. In the physician's judgement, the information from those images would be used to help you and your doctor make decisions about your health care. That may mean that a "negative" scan (where everything looks "normal") means you do not need to have treatment. It may also mean that a scan shows something that you want to treat. Your doctor should be able to tell you how the imaging information will affect and contribute to your clinical care.

Over the past 20 years, many efforts have been made to optimize the use of radiation in medical imaging. CT scans now take into account the size of the patient and the specific clinical question being asked to help get high-quality images without using more radiation than is required. If you have additional questions about your exams specifically, you can ask to speak with a radiologist, a medical physicist, or a health physicist at the facility where you have your imaging done.

Radiation can cause a lot of anxiety, but when used appropriately it can provide life-saving information. I hope this helps you to get the answers you need and relieves some of your stress associated with your imaging exams.

Rebecca Milman, PhD, DABR

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 21 December 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.