How does radiation exposure from typical use of medical imaging compare with background radiation or accepted occupational exposures? In this analysis, authors used administrative data from a large insurer to evaluate cardiac imaging use in almost one million adults (age, <65) and estimated the effective dose of radiation from such procedures.

From 2005 to 2007, 90,121 patients (9.5%) underwent at least one cardiac imaging procedure, with a mean cumulative effective dose of 16.4 millisieverts (range, 1.5–189.5 mSv). Most of the effective dose (74%) came from myocardial perfusion imaging (MPI). About half of all cardiac imaging procedures — and three quarters of MPIs and cardiac computed tomography scans — were performed in physicians’ offices. Effective radiation doses that exceeded the background level from natural sources by >3 mSv annually occurred in 92.3 per 1000 enrollees, and doses exceeding annual limits for occupational exposure (>20 mSv) occurred in 3.3 per 1000.

Comment: The questions, of course, are whether these imaging procedures were appropriate and whether risks from radiation exposure were offset by sufficient benefit. Editorialists point to ongoing efforts to minimize radiation exposure and contend that the estimates used here are too high. They also remind us that the morbidity and mortality associated with coronary heart disease can be mitigated by accurate diagnostic testing. However, as cumulative radiation doses become a bigger issue, alternative forms of testing that do not employ ionizing radiation will be needed and preferable.

Published in Journal Watch General Medicine August 5, 2010