Cardiac CT: are we underestimating the dose? A radiation dose study utilizing the 2007 ICRP tissue weighting factors and a cardiac specific scan volume

AimTo calculate the effective dose from cardiac multidetector computed tomography (MDCT) using a computer-based model utilizing the latest International Commission on Radiation Protection (ICRP) 103 tissue-weighting factors (2007), to compare this dose with those calculated with previously published chest conversion factors and to produce a conversion factor specific for cardiac MDCT.Materials and methodsAn observational study of 152 patients attending for cardiac MDCT as part of their usual clinical care in a university teaching hospital. The dose for each examination was calculated using the computer-based anthropomorphic ImPACT model (the imaging performance assessment of CT scanners) and this was compared with the dose derived from the dose–length product (DLP) and a chest conversion factor.ResultsThe median effective dose calculated using the ImPACT calculator (4.5 mSv) was significantly higher than the doses calculated with the chest conversion factors (2.2–3 mSv).ConclusionThe use of chest conversion factors significantly underestimates the effective dose when compared to the dose calculated using the ImPACT calculator. A conversion factor of 0.028 would give a better estimation of the effective dose from prospectively gated cardiac MDCT.