Radiation Risk for the Thyroid Gland

In this edition of Safety Corner, we will discuss the Radiation Risk for the Thyroid Gland

With more than 56,000 cases of thyroid cancer likely to be diagnosed in the U.S. in 2012, the incidence of thyroid cancer is increasing faster than any other cancer, the American Thyroid Association (ATA) noted. Although it is unlikely that radiation exposure is the predominant contributor to this trend, an increase in the use of diagnostic x-rays, particularly CT, is widespread and necessitates the protection of the thyroid gland when possible to diminish thyroid cancer risk.

In a 2005 brochure (and reaffirmed in 2012) about thyroid cancer, the ATA stated that "routine x-ray exposure (e.g., dental x-rays, chest x-rays, and mammograms) does not cause thyroid cancer."

The ATA's chief conclusions and recommendations are as follows:

• The risk of thyroid cancer arising from radiation exposure strongly depends on age at exposure. It is only recently that a thyroid cancer risk for exposure after age 15 has been observed. This risk is low, but not absent.
• For the purposes of public health planning, most experts and organizations assume that the risks for cancer, including thyroid cancer, are reduced proportionately with the dose.
• The necessity of all diagnostic x-rays should be evaluated before they are performed. This must include the potential risks as well as the potential benefits to the patient. This must also include a consideration of the alternative methods for obtaining the same or related clinical information.
• Thyroid-protective collars should be used for all dental x-rays when they do not interfere with the examination. Thyroid-protective collars are not needed for screening mammograms.
• The patient or the patient's decision maker should be made aware of the potential risks and benefits of radiation in a manner that is understandable to them.
• Clinicians should be adequately informed about the potential risks of radiation and the general principles of radiation dosimetry, especially as they relate to children and to the thyroid.