摆位偏差对管电流调制CT检查辐射剂量和图像质量的影响  

Positioning deviation on tube current modulation effects of radiation dose and image quality of CT examination

作　　者：张曼曼 王静 王梦廷 刘玲 梁保辉 Zhang Manman;Wang Jing;Wang Mengting;Liu Ling;Liang Baohui(Bengbu Medical College,Academy of Medical Imaging,Anhui 233000,China)

机构地区：[1]蚌埠医学院医学影像学院,233000

出　　处：《山西医药杂志》2022年第18期2047-2051,共5页Shanxi Medical Journal

基　　金：安徽高校自然科学研究项目(KJ2021A0746);安徽省省级大学生创新创业训练计划(S202010367118)。

摘　　要：目的利用放射模拟人研究摆位误差对自动管电流调制(ATCM)技术的胸部CT辐射剂量和图像质量的影响。方法使用GE Revelution 256 CT的ATCM技术,将放射仿真模拟人仰卧位放置CT床上,扫描定位像时球管入射角度为180°,将胸部扫描的中心与CT机架中心重合时床高118.5 cm为基准,调整床高度分别为103.5 cm、108.5 cm、113.5 cm、123.5 cm、128.5 cm和133.5 cm进行扫描。辐射剂量指标为容积CT剂量指数(CTDIvol)、体型特异性辐射剂量(SSDE)以及管电流调制曲线。图像客观质量评价指标为信噪比(SNR)、对比噪声比(CNR)和品质因子(FOM)。结果在床高为128.5 cm处SSDE最高,在床高103.5 cm处SSDE最低,但图像噪声增加;床高不同,脊柱和胸骨噪声变化不同;软组织在床最高和最低处噪声下降,肺组织在床最高处噪声降低,在床最低处噪声增加。结论管电流调制的胸部CT垂直位置偏差影响ATCM技术的发挥。定位偏离等中心点上下15 cm时,基准线两侧辐射剂量呈上升趋势。定位偏离等中心点不同组织的噪声变化不同,床越低噪声会增加。Objective To study the effect of positioning deviation on chest CT radiation dose and image quality of automatic tube current modulation(ATCM)by using radiation simulators.Methods The simulator was placed supine on the CT bed,and the incident Angle of the spherical tube was 180°when scanning the positioning image,by using the ATCM technology of GE Revelution 256 CT.The simulated human chest scanning center coincided with the CT frame center,and the bed height was 118.5 cm as the benchmark.The bed height was adjusted to 103.5 cm,108.5 cm,113.5 cm,123.5 cm,128.5 cm and 133.5 cm and scanned respectively.The volumetric CT dose index(CTDIvol),the body type-specific radiation dose(SSDE),and the tube current modulation curve are used as radiation dose indicators.The signal-to-noise ratio(SNR),comparative noise ratio(CNR)and figure of merit(FOM)are used as the objective evaluation indicators of image quality.Results The SSDE was the highest at bed height of 128.5 cm and the lowest at bed height of 103.5 cm,but the image noise increased.The changes of bed height and noise of spine and sternum were different.Soft tissue noise decreased at the top and bottom of the bed,lung tissue noise decreased at the top and increased at the bottom of the bed.Conclusion The vertical position deviation of chest CT modulated by tube current affects the performance of ATCM technique.When the location de-viated from the isocenter by 15 cm,the radiation dose on both sides of the baseline showed an upward trend.

关 键 词：体层摄影术 X线计算机 胸部 辐射剂量 偏离等中心点 自动管电流调制技术 

分 类 号：R816.4[医药卫生—放射医学]