基于成年人体重及体重指数估算胸腹部CT体型特异性辐射剂量

Estimation of Body Type-Specific Radiation Dose of Chest and Abdominal CT Based on Adult Weight and Body Mass Index

目的提出基于成年人体重及体重指数(BMI)估算胸部、上腹部、腹部-盆腔CT检查体型特异性辐射剂量的方法。资料与方法回顾性分析2019年12月—2020年11月在中国科学院大学宁波华美医院接受CT扫描的受检者的临床及CT资料,筛选出其中无明显病变的419例,按扫描部位分为胸部扫描组153例、上腹部扫描组94例、腹部-盆腔扫描组172例。对CT扫描范围内最中间的横断面图像进行数据测量及计算,测量前后径与横径,计算有效直径(ED)和基于ED的体型特异性辐射剂量(SSDE);测量横断面积及平均CT值,计算水等效直径(Dw)和SSDE。分析成年人体重及BMI与相关CT检查部位SSDE与SSDE的相关性。使用线性回归建立各部位成年人体重及BMI与SSDE、SSDE的回归方程,得出基于成年人体重及BMI估算胸部、上腹部、腹部-盆腔CT检查体型特异性辐射剂量的具体转换系数。结果在3组中,体重及BMI均与SSDE及SSDE呈正相关(r=0.688~0.858、0.847~0.872、0.813~0.867,P<0.001)。在胸部扫描组中,可使用BMI估算SSDE,其转换系数为0.666;在上腹部扫描组中,可使用体重估算SSDE,体重和BMI与SSDE的转换系数分别为0.198和0.534;腹部-盆腔扫描组中,建议仅使用BMI估算腹部-盆腔CT检查的SSDE,其转换系数为0.702。结论用体重及BMI估计胸部、上腹部、腹部-盆腔基于ED或Dw的成年人SSDE的方法简单、有效,上腹部的剂量估计直接用体重更加便捷,用BMI估计胸部基于Dw的成年人SSDE更可靠。

Purpose To propose a method to estimate size-specific doses of chest,upper abdominal,and abdominal-pelvic CT scans based on adult body weight and body mass index(BMI).Materials and Methods A retrospective analysis was conducted on clinical and CT data of patients who underwent CT scans from December 2019 to November 2020 in Ningbo Hwamei Hospital,University of Chinese Academy of Sciences.A total of 419 cases without obvious lesions were eventually selected and divided into three groups,including 153cases in chest scans group,94 cases in upper abdominal scans group,and 172 cases in abdominal-pelvic scans group.Data measurements and calculations were carried out on the middlemost cross-section out of the entire CT scan length.Anteroposterior dimensions and lateral dimensions were measured to calculate the effective diameters(ED),as well as the ED-based size-specific dose estimates(SSDE).In addition,cross-sectional areas and mean CT values were measured to calculate water equivalent diameters(Dw)and Dw-based SSDE(SSDE).The correlation between adult weight and BMI with SSDEand SSDEat relevant CT examination sites was calculated.The linear regression equations of body weight and BMI of each part in adults with SSDEand SSDEwere established to obtain the specific conversion factors for SSDE in the chest,upper abdominal and abdominal-pelvic CT.Results Among the three groups,body weight and BMI were strongly correlated with SSDEand SSDE(r=0.688-0.858,0.847-0.872 and 0.813-0.867,respectively;P<0.001).For chest CT scans,BMI could be used to estimate SSDEwith a conversion factor of 0.666;for upper abdominal CT scans,body weight could be used to estimate SSDEwith conversion factors of 0.198 and 0.534 to convert body weight and BMI to SSDE,respectively;for abdominal-pelvic CT scans,it could be recommended to use only BMI to estimate the SSDE,using a conversion factor of 0.702.Conclusion It is a simple and effective approach to assess adult SSDEor SSDEin chest,upper abdominal and abdomen-pelvic CT scans via body weight and BMI.Furthermore,it is more convenient to carry out dose estimation of the upper abdomen directly with body weight,and more reliable to assess adult SSDEof the chest with BMI.