The University of Colorado Radiology Adult Dose-Risk Smartcard.

The Department of Radiology at the University of Colorado School of Medicine in Denver developed the Adult Dose-Risk Smartcard shown in Figure 1 to provide a convenient, pocket-sized reference card communicating the effective doses and radiation risks of common adult radiologic examinations. The smartcard was distributed to University of Colorado radiologists, referring physicians, medical physicists, and attendees at the recent 1-day Colorado Radiation Safety Symposium: Risk and Dose Optimization in Radiology. The card is intended to facilitate radiation risk consultations and improve patient satisfaction by simplifying essential facts on radiation dose and risk to a level understandable by referring physicians and their patients. This allows patients to make more informed decisions about the relative risks of radiologic examinations compared with the medical risk caused by refusing a recommended imaging procedure. Estimates of effective doses for most adult procedures come from the published literature, many from the article “Effective Doses in Radiology and Nuclear Medicine: a Catalog” by Mettler et al [1]. Mammographic dose (and risk) estimates come from recent articles by Hendrick et al [2,3]. Most estimates of cancer risk from the low-dose radiation exposures in the smartcard are based on the latest report from the International Commission on Radiological Protection [4], whose radiation risk stimates are age averaged (for dults aged 18-65 years) and gender averaged, yielding an overall risk for fatal cancer induction of 4.1% (a 0.041 probability factor) per sievert or 0.0041% (a 0.000041 probability factor) per millisievert. Age-dependent estimates of mammographic risks specific to female patients are based on the National Academy of Sciences Biological Effects of Ionizing Radiation report [3,5]. Both International Commission on Radiological Protection [4] and Biological Effects of Ionizing Radiation [5] risk estimates for solid tumors assume a linear no-threshold relationship between radiation dose and cancer risk to extrapolate the high-dose, high-linear energy transfer exposures (eg, to atomic bomb survivors, in whom subsequent radiation-induced cancers have been documented) to the low-dose, low-linear energy transfer exposures from diagnostic radiology examinations, for which no direct cancer-causing effect has been documented in humans. There is good evidence from studies of atomic bomb survivors that organ doses 100 mSv result in a small, but statistically significant, increase in cancer risk. The risks stated on the University of Colorado smartcard assume a linear no-threshold model to extrapolate the dose-risk relationship down to the low doses used in diagnostic examinations. These risk estimates are conservative in terms of protecting patients and may overestimate rather than underestimate radiation risk from medical examinations. To put doses and risks in perspective, the smartcard permits the