Dual Source CTを用いた冠状動脈造影CTにおける使用基準の有用性 心電同期高速二重螺旋スキャンと: 螺旋スキャン，非螺旋スキャンの被ばく線量比較

摘要

We believe that the patient exposure dose differs by heart rate for a coronary computed tomography angiography (CCTA), and we attempted to reduce patient exposure dose of the CCTA. Specifically, we made a clear difference of exposure dose between heart rate and optimal cardiac phase or some imaging methods. Next, we established criterion of the CCTA in our hospital, and usefulness was discussed. For examination methods, patients with a heart rate below 60 beats per minute (bpm) received a high-pitch spiral scan (Flash Spiral mode), those between 61 to 70 bpm received a step and shoot scan (SAS mode), and those of ＞70 bpm or an irregular heart rate received low-pitch spiral scan (Helical mode). The results of the clinical study showed that patient exposure dose reduced 87％ in Flash Spiral mode (1.93±0.26 mSv) and 66％ in SAS mode (4.88±1.24 mSv) compared with Helical mode (14.35±3.42 mSv). In our present study, we proved the usefulness of our criteria using CCTA. If the results of our present study become guidelines of CCTA users, we suggest that total patient exposure dose can be reduced.%近年，多列検出器(multi-detector-row)computed tomography(MDCT)装置は空間分解能，時間分解能などに目覚しい進歩を成し遂げていることから，特に冠状動脈造影CT(coronary CT angiography: CCTA)検査に関して必要とされている.また冠状動脈造影(coronary angiography: CAG)と比べ侵襲性が低いため，冠状動脈疾患のスクリーニングとして用いられるようになつた.しかし，CCTAは心電図(electrocardiogram: ECG)同期併用下で行われるため撮影時間が長くなり，一般的に行われている他のCT検査に比べ被ばく線量は多い.