冠動脈CTと冠動脈造影における放射線被曝線量の比較 : ファントムによる基礎的検討(<特集>心臓関連論文特集号)

概要

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The new type of coronary angiography (CAG) that uses 40mm volumetric computed tomography (VCT) has great potential for cardiac disease. However, it is still necessary to be cognizant of exposure dose. We measured doses of CAG by both VCT and cardiovascular X-ray using a body phantom within 170 glass dosimeters. VCT protocols were 120kV, 570mA, and 0.35sec/rot with and without the dose-reduction features (small cardiac X-ray beam filter and ECG mA modulation). The cardiovascular X-ray protocol was Auto (65-77kV)kV, Auto(41-46mA)mA, 5 sec×11 shots+11 min fluoroscopy(minimum protocol for screening). VCT with and without the dose-reduction features has the same dose distribution, however, the dose-reduction features reduced the amount of dose by about 40-50%. For VCT with those features, measured dose was about 70mGy in the cardiac area and 60mGy at the skin of the back, whereas those of cardiovascular X-ray were 10mGy and 30mGy. We measured detailed dose distributions and variations in the phantom, and we also demonstrated the possibility of VCT's dose-reduction features. The CT dose was still higher than that of cardiovascular X-ray, however, there were advantages of CT scanning, for instance, information about calcification, soft plaque, and 3D visualization. We think it is important to use both systems with an understanding of their advantages and limitations.
社団法人日本放射線技術学会の論文
2007-06-20