Effect of off-center positioning based on ATCM technique on CT image quality and radiation dose on chest
10.3969/J.ISSN.1672-8270.2023.12.002
- VernacularTitle:基于自动管电流调制技术偏中心定位对胸部CT图像质量和辐射剂量的影响
- Author:
Ying YUAN
1
;
Mei BAI
;
Lei QIAO
Author Information
1. 首都医科大学附属北京友谊医院放射科 北京 100050
- Keywords:
Automatic tube current modulation(ATCM)technique;
Off-center;
Radiation dose;
Image quality
- From:
China Medical Equipment
2023;20(12):5-9
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the effect of off-center positioning on image quality and radiation dose when automatic tube current modulation(ATCM)technique is used in computed tomography(CT)scanning on chest.Methods:A GE Revolution 256-row spiral CT machine was used to perform CT scan on a simulation phantom of chest by adopting ATCM technique,and the off-center situation was simulated by adjusting the height of the examination bed.The posterior-anterior localization image scanning method was adopted to enroll the posterior-anterior localization image group,and the dual-localization image scanned the dual-localization image group,and both groups were centered as the mid-axillary line of the body.The different positions of phantom in scan field were simulated through adjusted the height of the examination bed.The phantom of each group was scanned at 80 mm,60 mm,40 mm,20 mm,0 mm,-20 mm,-40 mm,-60 mm and-80 mm of the mid-axillary line.Both groups were scanned under the same scanning parameters,and the volume CT dose index(CTDIvol)and dose-length-product(DLP)were recorded for each group.The objective noise(SD)of the imageries of two groups were measured and compared,and two attending physicians with 5 years of work experiences of radiology department adopted respectively dual blind method to conduct subjective scoring for ground glass nodules(GGN),and the mean of scores was used to evaluate the results.Results:The CTDIvol value of the posterior-anterior localization image group was 4.56 when the off-center was-80 mm of the mid-axillary line,which increased 54.05%than that when the off-center was 0 mm.The CTDIvol value was 2.12 when the off-center was 80 mm,which decreased 28.38%than 0 mm of off-center.The CTDIvol value was 3.20 when the dual-localization image group was located at-80 mm of off-center,which decreased 3.61%than 0 mm of off-center.The CTDIvol value was 3.31 when the off-center was 80mm,which decreased 0.30%than that when off-center was 0mm.There was no statistically significant difference in subjective GGN scores between the two groups at different positions of off-center.Conclusion:Off-center positioning scan has greater effect on radiation dose when using posterior-anterior localization image scans,while the off-center positioning scan does not have effect on radiation dose when using dual localization image scan.The dual localization image should be adopted to perform CT scan on chest when the lateral center of the thorax cannot be determined in clinical practice,which can reduce the radiation dose of patients.
