| Summary: | 碩士 === 中臺科技大學 === 醫學影像暨放射科學系暨研究所 === 106 === Computer Tomography Cardiovascular Photography is one of the most useful techniques for identifying coronary artery calcification. It can provide accurate assessment of calcification scores and condition of blood vessel obstruction. An optimal computer tomography image quality assists radiologists to obtain more accurate judgments in diagnosing lesions in reality. Taguchi dynamic analysis was used to evaluate the optimal combination of factor settings for computer tomography scan with three different acrylic phantoms in this study. Eighteen combinations of various factor settings were organized using Taguchi’s L18 orthogonal array. The five factors for CT scan included (A) peak voltage (kVp), (B) tube current time product (mAs), (C) spiral CT pitch, (D) Field of view (FOV) and (E) slice thickness, respectively. The CT model was Philips brilliance 64-slice CT. The customized line group phantom was placed in the thorax phantom to simulate an adult’s cardiac tissue. Accordingly, three images derived from each combination was graded and averaged by three well trained radiologists under double-blinded criteria to ascertain the reproducibility and accuracy to minimize the systematic uncertainty. The derived results were further reviewed through ANOVA to verify its importance in reality and the dominant factor was identified as Pitch. The optimal settings for 50, 70, and 90 kg phantom was 140 kVp, 700 mAs, 0.16 spiral CT pitch, 250 mm FOV, 0.90 mm slice thickness; 140 kVp, 700 mAs, 0.20 spiral CT pitch, 220 mm FOV, 0.80 mm slice thickness; and 140 kVp, 800 mAs, 0.18 spiral CT pitch, 220 mm FOV, and 0.90 mm slice thickness, respectively. Thus, the optimal setting for CT image for cardiac patients was accomplished in this study. Further, the corresponded spatial resolution for CT was 2.62, 2.55, and 2.66 mm, respectively for 50, 70, and 90 kg phantom according to a revised t-test algorithm. The image quality was greatly improved by Taguchi dynamic analysis than did the conventional setting in this study.
|
|---|
