Study on the Effect of Pitch on the Quality of Chest CT Image and Radiation
Dose Under Automatic Tube Current Regulation
YUAN Ying1,2, ZHONG Zhaohui2, WU Tianqi1, BAI Mei1
1. Department of Medical Engineering, Xuanwu Hospital of Capital Medical University, Beijing 100053, China;
2. Department of Radiology, Beijing Friendship Hospital of Capital Medical University, Beijing 100050, China
Abstract：Objective To evaluate the effect of pitch on decrease low-dose chest CT image quality and radiation dose with automatic tube
current modulation (ATCM) technique. Methods The chest simulation module was scanned using ATCM technology by GE Optima
CT680 CT machine, and there were 3 groups of scans. The pitch of the three groups were 0.5161:1 in group A, 0.984:1 in group B
and 1.375:1 in group C, respectively. The noise index (NI) were set to 10, 15, 20, 25 and 30 in each group, respectively. CT dose index
volumes (CTDIvol) and dose length product (DLP) were recorded. Standard Deviation (SD) of axial scan images at slice thickness
of 5 mm were measured as objective noises. Ground glass nodules (GGN) of axial images with slice thickness of 5mm were assessed
by two experienced radiologists blinded to the CT parameters. The degree of inter observers concordance was evaluated by Kappa
test. Results The CTDIvol was 8.45, 3.17, 2.04, 1.33 and 1.00 in group A when the NI was 10, 15, 20, 25 and 30, which decreased by
22.19%, 22.22%, 23.60%, 20.36% and 13.04% respectively compared with group B. Group C have a radiation dose reduce of 4.2%,
-0.1%, 0.4%, -0.4% and -2.3% compare with group B. There was no significant difference in both objective image quality and GGNs
assessment between different pitches with identical NI. Kappa value of GGNs assessment was substantial or almost perfect. Conclusion
When using ATCM technology, chest CT scan can optimize radiation dose by reducing the pitch on the premise of ensuring image quality.
袁颖1,2，钟朝辉2，吴天棋1，白玫1. 自动管电流调节技术下螺距对胸部CT图像质量及辐射剂量影响的体模研究[J]. 中国医疗设备, 2019, 34(1): 74-77.
YUAN Ying1,2, ZHONG Zhaohui2, WU Tianqi1, BAI Mei1. Study on the Effect of Pitch on the Quality of Chest CT Image and Radiation
Dose Under Automatic Tube Current Regulation. China Medical Devices, 2019, 34(1): 74-77.
