In the Bermuda Sun this month, Tara Soares discusses radiation exposure and whether a thyroid guard is needed during a mammogram.
WEDNESDAY, APR. 11: Every few months, one of our staff members receives a call or email asking if Bermuda Cancer and Health Centre have thyroid guards available for patients to use during their mammogram.
The interest in thyroid guard use for dental x-rays and mammograms became a hot topic of discussion, and controversy, as a result of an email which quickly went viral and raised alarm based on a 2010 episode of Dr. Oz’s TV show. During the show Dr. Oz stated that thyroid cancer is the fastest growing cancer in women and that women should be asking for a thyroid guard for use during their mammogram and when getting dental x-rays.
As a result of the anxiety and apprehension raised from the email, the American College of Radiology (ACR) and the Society of Breast Imagers (SBI) (Radiologists specially trained in breast imaging) issued a formal Statement on Radiation Received to the Thyroid from Mammography.
Erroneous
The joint statement indicated that the media report was ‘erroneous’ in stating that the small amount of radiation a patient receives from a mammogram may significantly increase the likelihood of developing thyroid cancer.
The concern simply is not supported in scientific literature.
During a mammogram, the small amount of x-rays used is directed at the breast tissue. The thyroid gland, which is at the base of the throat, is above the breast and located several inches away, therefore the thyroid is not exposed to the direct x-ray beam. The digital x-ray equipment is very well shielded and quality control tests are regularly performed to ensure it is operating optimally.
There is a tiny amount of what is called “scatter” x-rays (less than 0.005 milligray*) that will reach the thyroid during a mammogram. To put this amount of radiation in perspective, it is equivalent to the amount you will receive from natural background radiation by simply standing outside your house or sitting in your garden for 30 minutes. The joint statement further said that the thyroid cancer risk from this tiny amount of radiation scattered to the thyroid is incredibly small – less than 1 in 17,100,000 (0.000006 per cent) women.
The scientific analysis performed by the radiation experts indicate that the risk to the thyroid is shown to be very small — but why not ask for a thyroid guard anyway when having your mammogram? The ACR and SBI state that the use of a thyroid shield could interfere with the optimal positioning (of the breast) and could result in “artifacts – shadows” that might appear on the mammography image. Both of these factors could reduce the quality of the image and interfere with diagnosis. It may also result in the women needing extra images, which would not be needed if the thyroid guard was not used.
The result would be preventable and unnecessary additional x-ray exposure. Therefore, the use of a thyroid guard during mammography is not recommended by the breast specialists and radiology experts.
About the thyroid — It makes hormones that help control heart rate, blood pressure, body temperature and weight. Risk factors for thyroid cancer include gender (women have a higher risk), age, hereditary conditions and large doses of radiation (eg, cancer treatment to the head and neck) and radioactive fallout such as was experienced from the Chernobyl nuclear reactor disaster in 1986.
The mission of the American College of Radiology is to serve patients and society by maximizing the value of radiology, radiation oncology, interventional radiology, nuclear medicine and medical physics by advancing the science of radiology, improving the quality of patient care, positively influencing the socio-economics of the practice of radiology, providing continuing education for radiology and allied health professions and conducting research for the future of radiology.
Bermuda Cancer and Health Centre is an American College of Radiology accredited facility and is committed to minimizing unnecessary radiation exposure by having the latest digital technology, on-site breast specialists and by following established radiation protection principles.
A milligray is a unit of absorbed radiation equal to 0.001 Gray. One (1) Gray is a dose of one Joule of energy absorbed per Kilogram of matter.
Find out more by visiting Bermuda Cancer and Health Centre at 46 Point Finger Road, visiting www.chc.bm or calling 236-1001. As the on-site radiation expert at Bermuda Cancer and Health Centre, Tara Soares is available to answer questions from patients, families or members of the public about the uses of radiation. Tara E. Soares, BSc, M.Sc Health and Radiation Physics is Executive Director at Bermuda Cancer and Health Centre.
