부산대학교 도서관

The purpose of this study is to understand the CT growth and radiation dose level, to determine the diagnostic reference level, and to compare the radiation doses between MSCT and SSCT. The received rate of questionnaires was 56 %, and the percentiles for MSCT and SSCT were almost equal. The majority of the first survey in 2003 is SSCT, however, MSCT increased rapidly during 2003 to 2008. The CT using frequency raised about 70 % from 2003 to 2007 while the total number of CT scanners didn’t change. The wider scan range, shorter tube rotation time, and excellent image processing software reduce the scanning time and then make more people undergo CT examinations. The technical factors, such as kVp, mAs, pitch, for brain, thoracic, high resolution chest, abdomen, abdomen-pelvis, and whole body scans were analyzed. The CTDIs, DLP, and effective doses were calculated by ImPACT CT dosimetry calculator with UK SR-250 Monte Carlo simulation data set. The variation for effective tube current time product was the largest. The effective mAs was dramatically different between SSCT and MSCT. The effective doses for MSCT were larger than those for SSCT about 16 % to 60 %, especially in brain scan (p＜ 0.05). The diagnostic reference level set in this study was lower than EC recommended values. All of the results of this study were very valuable to understand the computed tomography radiation dose in Taiwan.