저관전압 흉부 CT검사 시 CT value의 변화에 따른 영상평가

Evaluation of image quality as change of CT value in low tube-voltage chest CT scan

Purpose Experiments carried out on the patients who visited this department for pulmonary disease and need CT scans for Follow-up to observe change of CT value, evaluation of image quality and decrease of radiation dose as change of tube voltage Materials and Methods Subjects were the patients of 20 persons visited this department for pulmonary disease and Somatom Sensation 16(Siemens, Erlangen, Germany) was used. Measurement of CT value as change cf tube voltage was done by setting up ROI diameter of 1cm at the height of thyroid, aortic arch, right pulmonary artery in arterial phase image using 100OkVp, measuring 3 times, and recorded the average. CT value of phantom was measured by scanning phantoms which means contrast media diluted by normal saline by various ratio with tube voltage of 80kVp, 100kVp, 120kVp, 140kVp and recorded the average of 3 CT values of center of phantom image. In analysing radiation dose, CTDIvol. values of the latest arterial phase image of 120kVp and as this research set that of 100kVp were analyzed comparatively. 2 observers graded quality of chest images by 5 degrees (UnaccepTable, Suboptimal, Adequate, Good, Excellent diagnostic quality). Results CT value of chest image increased at 100kVp by 14.06%~27.26% in each ROI than 120kVp. CT value of phantom increased as tube voltage lowered at various concentration of contrast media. CTDIbol. decreased at 100kVp(5.00mGy) by 36% than 120kVp(7.80mGy) in radiation dose analysis. here were 0 UnaccepTable, 1 Suboptimal, 3 Adequate, 10 Good, 6 Excellent diagnostic quality in totally 20 persons. Conclusion Chest CT scanning with low kilo-voltage for patients who need CT scan repeatedly can bring images valuable for diagnose, and decrease radiation dose against patients.