일 지역 종합병원 영상의학과 MDCT선량에 대한 연구

Abstract

Abstract The difference of radiation dose of MDCT due to different proto cols between hospitals was analyzed by CTDI, DLP, the number of Slice and the number of DLP/Slice in 3 0 cases of the head, the abdomen and the chest that have 10 cases each from MDCT examination of the depa rtment of diagnostic imaging of three general hospitals in Gyeongsangbuk-do. The difference of image quality, CTDI, DLP, radiation dose in the eye and radiation dose in thyroid was analyzed after both helical s can and normal scan for head CT were performed because a protocol of head CT is relatively simple and head CT is the most frequent case.Head CT was significantly higher in two-thirds of hospitals com pared to A hospital that does not exceed a CTDI diagnostic reference level (IAEA 50mGy, Korea 60mGy) (p<0. 001). DLP was higher in one-third of hospitals than a diagnostic reference level of IAEA 1,050mGy.cm and Korea 1,000mGy.cm and two-thirds exceeded the recommendation of Korea and those were significant ly higher than A hospital that does not exceed a diagnostic reference level (p<0.001).Abdomen CT showed 119mGy that was higher than a diagnostic refe rence level of IAEA 25mGy and Korea 20mGy in one-third. DLP in all hospitals was higher that Korea recommendation of 700mGy.cm. Among target hospitals, C hospital showed high radiation dose in all tests b ecause MPR and 3D were of great importance due to low pitch and high Tube Curren.To analyze the difference of radiation dose by scan methods, no rmal scan and helical scan for head CT of the same patient were performed. In the result, CTDI and DLP of helical CT were higher 63.4% and 93.7% than normal scan (p<0.05, p<0.01). However, normal scan of radi ation dose in thyroid was higher 87.26% (p<0.01). Beam of helical CT looked like a bell in the deep par t and the marginal part so thyroid was exposed with low radiation dose deviated from central beam. In addition , helical scan used Gantry angle perpendicularly and normal scan used it parallel to the orbitomeatal line. Ther efore, radiation dose in thyroid decreased in helical scan. However, a protocol in this study showed higher r adiation dose than diagnostic reference level of KFDA. To obey the recommendation of KFDA, low Tube Curren and h igh pitch were demanded. In this study, the difference of image quality between normal scan and helical scan was not significant. Therefore, a standardized protocol of normal scan was generally used and pro tective gear for thyroid was needed except a special case.