Organ dose and scattering dose for CT coronary angiography and calcium scoring using automatic tube current modulation

Noninvasive coronary angiography and calcium scoring with the use of multi-detector computed tomography scanners are feasible for reliably detecting coronary artery disease. The purpose of this study is to investigate organ dose and scattering dose for CT coronary angiography and calcium scoring using automatic tube current modulation. Organ doses of an anthropomorphic phantom were estimated using LiF:Mg,Cu,P thermoluminescent dosimeter (TLD) chips. The dose profiles inside and outside the scanning regions were measured. Effective doses for coronary angiography and calcium scoring without using automatic tube current modulation are respectively 12.72 ± 2.06 and 1.69 ± 0.30 mSv. Using automatic tube current modulation can reduce effective dose by 43% for coronary angiography, and 24-32% for calcium scoring. Scatter doses at the point of 10 cm away from the margin of scanning region decreased to 5-9% of in-plane doses. Using automatic tube current modulation can effectively reduce radiation doses inside the CT scanning region.