Answer to Question #14287 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:


I am worried about a 3-D mammogram I had lately. I see differing facts online regarding the radiation exposure to the breast. I had one view of my left breast and five of my right. I found an article online for the Hologic machine that was helpful and more information at the Hologic Genius machine website. The information indicated the dose was 2.65 mGy for Combo mode and 1.45 mGy for Tomo mode. Does this mean if they did all images in combo mode that my right breast received 13.25 mGy? If it is truly that high, I am worried I may have increased my risk of breast cancer. I am 34. I have also heard at my age breast tissue might be more likely to be damaged than older tissue and this is why it is not generally recommended that women under 40 have a mammogram. I am worried the mammogram may have done more harm than good. I would really appreciate someone helping me break this down. 


You have found some good information online. I hope I can help make some sense of it for you.

The amount of radiation used during a mammogram is different for different patients. For patients with larger or denser breasts, slightly more radiation is needed to get a good image. The information you found is for an "average" breast. Your dose may have been slightly more or less than this.

We can compare the dose from a mammogram to naturally occurring background radiation to which we are all exposed. A woman living in the United States receives about 25 mGy to breast tissue each year. (In Denver, the background radiation is more than 50 mGy per year).

It is very difficult to tell scientifically what the exact risk is from 13 mGy of radiation to the breast, because the risk is either very, very small or may not exist at all. You are correct that breast tissue is more sensitive to radiation when women are between the ages of about 12 until 40. However, 13 mGy is still below the amount of radiation where we know there to be an increased risk of developing cancer.

For most women, the risk from the radiation used in mammography is much lower than the benefits of diagnosing breast cancer early. I recommend that you discuss the risks and benefits with your physician. He or she can help provide you with additional information to help you make a decision that is best for you.

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 8 December 2021. 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.