Medical Group Makes Recommendations for Thyroid Protection

Norra MacReady

June 18, 2012

June 18, 2012 — Responding to a rapid global increase in the incidence of thyroid cancer, the American Thyroid Association (ATA) has released a policy statement with recommendations for minimizing radiation exposure of the thyroid whenever possible.

"In the United States in particular, [thyroid cancer] is increasing faster than any other cancer, with more than 56,000 people likely to be diagnosed" in 2012 alone, the authors warn in the statement published online June 13 on the association's Web site.

The thyroid is extremely susceptible to radiation-induced carcinogenesis, making the risk for radiation exposure of special interest to the ATA. Radiation is probably not the major culprit behind the explosion of thyroid cancer cases. However, the authors warn that use of diagnostic X-rays, particularly computed tomography (CT), which uses even higher doses of radiation than conventional X-rays, has grown in recent years, and that more aggressive measures should be taken to protect the thyroid.

The risks for thyroid radiation are inversely related to age, being highest in children and decreasing as they grow older. "It is only recently that a risk for exposure after the age of 15 has been observed," the authors write. In children and adults alike, the risk is dose-dependent.

As reported by Medscape Medical News, an unrelated retrospective analysis published in the June 13 issue of JAMA shows that the number of CT examinations given to members of integrated healthcare systems tripled from 1996 to 2010, resulting in a quadrupling of per capita CT radiation exposure. The average effective dose of radiation from medical imaging increased by 3.2% annually, from 4.8 mSv in 1996 to 7.8 mSv in 2010. Use of all imaging modalities increased with increasing age.

The ATA statement makes 6 key recommendations:

  1. Evaluate the necessity of all diagnostic X-rays before they are performed.

  2. Patients or their decision makers should be informed of the risks and benefits of any diagnostic procedure in a way that is understandable to them.

  3. Clinicians should be educated on the risks for radiation and the general principles of radiation dosimetry, "especially as they relate to children and the thyroid."

  4. The benefits of mammography outweigh any risks to the thyroid. Shielding of the thyroid during mammography is not recommended.

  5. The use of thyroid shields is recommended in conjunction with all other diagnostic radiographies and CT scans, with the goal being to reduce exposure of the thyroid to radiation as much as possible.

  6. As with other diagnostic radiation, the ATA recommends that thyroid radiation exposure during dental examinations be minimized as much as possible without compromising clinical goals. In addition, the ATA "urges a reconsideration of the less stringent requirement put forth for thyroid shielding in adults as compared to children. The ATA also recommends that efforts be made to encourage and monitor compliance with the American Dental Association...and [National Council on Radiation Protection and Measurements] guidelines and to reduce, as much as possible, the areas of ambiguity in them."

The recommendations are based on "robust" literature reviews of the effects of medical radiation on the thyroid, as well as "a large body of research on the general health risks of radiation."

Policy Statement on Thyroid Shielding During Diagnostic Medical and Dental Radiology. Published online June 13, 2012. Full text

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