CT and radiation

i realize that i have spent a disproportionate amount of time writing about the risks of CT scan (and xray exposure in general). but there was a really good editorial in the NY times today by a cardiologist and radiologist (see http://www.nytimes.com/2014/01/31/opinion/we-are-giving-ourselves-cancer.html?ref=todayspaper). their points:

--cancer deaths are increasing relatively, as heart disease (the major killer) mortality has decreased over the decades

--medical radiation exposure has increased 6-fold from 1980s to 2006

--one in 10 americans get a CT scan every year (and many more than 1/yr), with radiation 100 to 1000 times higher than regular xray

--british study of kids exposed to multiple CTs found 3x incidence of leukemia and brain cancer

--? role of direct-to-consumer advertising or financial incentives of MDs.  though i would add here that xrays have become part of the "culture" and patient expectations: patients often come to me requesting an xray/CT etc, and i often need to spend significant amounts of time dissuading them of the need.

--Natl cancer institute in 2009 estimated that CT scans resulted in 29,000 excess cancer cases, and 14,500 excess cancer deaths. these editorialists estimate that 3-5% of all future cancers may be from medical imaging

--there is large variance of dose/xray from one institution to another

--they promote using the Choosing Wisely website to help patients (and providers) decrease xray utilization

one particular concern, not mentioned above, is the new USPSTF recommendation to do annual low-dose CT screening of all current smokers aged 55-80 with smoking history of >30 pack-years, or those who stopped smoking within the past 15 year. this was based on the natl lung screening trial, which found that annual low dose CT screening (for only 3 years, but then followed another 3.5 yrs) in those aged 55-74 (for some reason USPSTF increased the age to 80!!) decreased mortality by 20% (which translated to absolute benefit of only 62 deaths/100,000 person-years), but with a 25% false positive screening rate leading to more radiologic procedures (so that on average the low-dose CT was actually equal to that of a regular CT with 8mSv radiation exposure, and that this degree of radiation exposure would create one cancer in 2500 screening people. (see prior email/blog for details)

and, the increased number of screens (up to 25 annual screens, if the person kept smoking), would undoubtedly augment many of these numbers (eg, adverse effects of continued screening, including psych; probably increased false positives with more biopsies and potential problems esp as people get older and likely have more COPD; and undoubtedly more iatrogenic cancers.....)