Rando 팬텀을 이용한 Multi-detector Computed Tomography의 Automatic Exposure Control 특성 평가

The Assesment of Automatic Exposure Control in Multi-detector Computed Tomography by Rando phantom

Purpose To assess reaction characterization of automatic exposure controller(AEC) system by each manufacturer according to changing of subject thickness and changes of image quality acquired by them and phantom. Materials and methods 64 multi-detector computed tomography by four manufacturers including Siemens(Somatom Definition, Erlangen, Germany), GE Healthcare(Lightspeed VCT, Milwaukee, USA), Philips(Brilliance, Cleaveland, USA), and Toshiba(Aquillion, Tokyo, Japan) were used for this study. The Rando phantom(AR1-200X, Fluke Biomedical, USA) which was to change thickness was used also. General scan condition was used in abdominal pelvic examination and all available function of AEC was used. We displayed in graph changing of each mAs value, and measured standard deviation of each noise value according to change of subject thickness. Results The range of fluctuation of mAs value by each manufacturers’ AEC was 207 mAs(from 265 to 58 mAs), 179,5 mAs(from 197 to 18 mAs), 127.5 mAs(from 184.5 to 57 mAs), and from 174 mAs(from 196 to 22 mAs) in S, G, P, T, respectively. Noise values measured in phantom images were 9.1±2.4, 11.43±2.65, 7.9±2.59, 8.96±2.67, in S, G, P, T, respectively. Standard deviation of each noise value according to change of subject thickness was maintained a regular value as from ±2.4 to ±2.67 in all the four equipments. Conclusion AEC system is valuable technique to reduce radiation exposure based on geometric structure of patient and clinical demand. Therefore, characterization of AEC system should be recognized, and needed for periodical phantom scan to confirm primary function.