The background for this controversy is the rising incidence of thyroid cancer, which has increased fourfold since the 1970s. The original episode in 2010 said that some of the increase could be due to radiation exposure from dental x-rays and mammograms, and advised the use of thyroid shields to reduce risk.
ACR-SBI statement on the use of thyroid shields (PDF FILE)
The associations put the estimated x-ray scatter delivered to the thyroid at less than 0.005 mGy, equivalent to 30 minutes of natural background radiation and resulting in a cancer risk of less than one in 17 million. ACR and SBI further cautioned patients against using thyroid shields, which the organizations said could interfere with optimal breast positioning and create artifacts, thereby potentially compromising diagnosis
A follow up programme was aired on April 14, but appeared to be deliberately engineered as a lecture to professionals on listening to what women want. This week's episode was ostensibly intended to set the record straight, with Oz, inviting experts from dentistry and radiology to comment on the email controversy and the pros and cons of thyroid shielding.
Radiology experts included Dan Kopans, Phil Evans and Jocelyn Rapelyea who tried to objectively answer the criticism.
Dan Kopans talked about the radiation dose being tiny to the thyroid and about cumulative dose. Phil Evans explained about how thyroid shields obscure much breast tissue, and the mammograms may need repeating. Jocelyn Rapelyea also explained that certain body habitus can prevent women from successfully wearing thyroid shields which of course are a fixed size.
Either way, the programme just muddied the waters, and the fact that the basis of the claim about thyroid cancer risk and mammography screening is unsubstantiated, was never addressed, means that women are more concerned than ever.
We have thyroid shields available at Moffitt Cancer Center for women who wish to wear them, but we, as most other centers do not offer them routinely, as they degrade the quality of the subsequent mammograms in many women.