At CapeRay our engineers are acutely aware that the design of Aceso, which has full-field digital mammography (FFDM) as one of its two imaging modalities, must ensure the dose to the patient is minimized. The radiation to which the breasts are exposed is known as the mean glandular dose (MGD), expressed in units of milligray (mGy), and in a standard mammography exam the MGD is approximately 4 mGy. Reducing the dose, however, degrades image quality and increases the risk of misdiagnosis, and so there must be a trade-off.
Four years ago Martin Yaffe and James Mainprize of Toronto published an article in Radiology entitled “Risk of radiation-induced breast cancer from mammographic screening.” Using mathematical simulation, they estimated that for a cohort of 100,000 women who each received 3.7 mGy annually from age 40 to 55 and thereafter biennially until 74 years, there would be 86 induced cancers and 11 deaths due to radiation. Despite these findings, Yaffe commented, “We really don’t have any direct evidence that any woman has ever died because of radiation received during her mammograms.”
Two researchers, Jeffry Siegel and James Walsh, have recently published a paper in Technology in Cancer Research and Treatment with the provocative title, “Does imaging technology cause cancer? Debunking the linear no-threshold model of radiation carcinogenesis.” They drew attention to the plethora of articles published in the scientific literature that claimed there was no such thing as a “safe dose” of ionizing radiation, while ignoring the literature demonstrating the opposite.
They emphasized that these “scientific” studies all based their estimates of cancer induction on the linear no-threshold (LNT) hypothesis of radiation carcinogenesis. Since the LNT model was being used by healthcare professionals to determine risk:benefit ratios, Siegel and Walsh argued the model needed to be carefully assessed: “Here, we review the myriad inadequacies of LNT and cast doubt on the various studies based on this overly simplistic model. It is of questionable validity, utility and applicability for estimation of cancer risks.”
The authors pointed out that the rate of spontaneous mutations in the human body is 2.5 million times higher than the mutation rate caused by low-dose background radiation in the environment, suggesting there was compelling evidence that we have evolved an ability to repair any damage caused by low-dose radiation exposure. They concluded, “Many people are focused on the dangers of radiation from medical imaging, but the risks associated with not undergoing a procedure are far higher – and generally ignored by the media.”