Imaging Technology
Feasibility study for calculating size-specific dose estimates based on weight and body mass index in CT abdomen-pelvic examination of adult population
Xu Jian, Wang Xiangquan, Yang Panfeng, Xie Yelei, Luo Kuangnan, Mao Dewang
Published 2020-07-25
Cite as Chin J Radiol Med Prot, 2020, 40(7): 549-553. DOI: 10.3760/cma.j.issn.0254-5098.2020.07.011
Abstract
ObjectiveTo explore the feasibility for taking weight and body mass index (BMI) to calculate the size-specific dose estimate (SSDE) in abdomen-pelvis CT examination.
Methods512 adult patients undergoing abdomen-pelvis CT examination were retrospectively analyzed. The in-house software based on MATLAB platform were used to calculate automatically water equivalent diameter (dw), size-dependent conversion factor (f), SSDE, together with their respective averaged values. The correlations between age, height, weight and BMI with dw were calculated by using Spearman correlation analysis. Two regression equations were established to calculate the SSDE (SSDEweight, SSDEBMI), one for the correlation of weight with dw based on first half of these cases and the other for that between BMI with dw based on another half as the cases to be verified. With reference of the SSDE derived from the in-house software, the averaged relative differences and root-mean-square errors in SSDEweightand SSDEBMI were calculated, respectively.
ResultsNo statistically significant correlation between age and dw (P>0.05) was shown, but weak correlation between height anddw(r=0.260, P<0.05), strong correlation between either weight or BMI withdw(r=0.879, 0.851, P<0.05). Two regression equations were described asdw=13.808+ 0.184×weight, dw=11.142+ 0.618×BMI. The mean SSDE, SSDEweight and SSDEBMI for the verified patients were (13.55±1.66) mGy, (13.84±2.03) mGy and (13.83±2.02) mGy, respectively. As compared to actual SSDE, the averaged relative differences in SSDEweight and SSDEBMI were 1.97% and 1.87%; 0.38% and 2.75% for male patients; 4.58% and 0.43% for female patients; 0.11% and 3.32% for patients with BMI<18.5 kg/m2;1.92% and 2.06% for those with 18.5 kg/m2≤BMI<24.0 kg/m2;2.57% and 1.57% for those with 24 kg/m2≤BMI<28.0 kg/m2;3.28% and -1.36% for those with BMI≥28.0 kg/m2. The averaged root-mean-square errors in SSDEweight and SSDEBMI were both 0.80 mGy; 0.65 and 0.67 mGy for male patients; 0.98 and 0.59 mGy for female patients; 0.73 and 1.03 mGy for underweight, 0.74 and 0.66 mGy for normal weight, 0.85 and 0.79 mGy for overweight, and 1.10 and 1.32 mGy for obesity.
ConclusionsWeight and BMI can be used as the surrogate dw to compute SSDE in adult abdomen-pelvis CT examination. However, Weight rather than BMI is more applied to male patients, and BMI is more suitable for female patients.
Key words:
Body mass index; Tomography, X-ray; Size-specific dose estimate
Contributor Information
Xu Jian
Department of Radiology, Zhejiang Provincial People′s Hospital, People′s Hospital of Hangzhou Medical College, Hangzhou 310014, China
Wang Xiangquan
Department of Radiology, Zhejiang Provincial People′s Hospital, People′s Hospital of Hangzhou Medical College, Hangzhou 310014, China
Yang Panfeng
Department of Radiology, Zhejiang Provincial People′s Hospital, People′s Hospital of Hangzhou Medical College, Hangzhou 310014, China
Xie Yelei
Department of Radiology, Zhejiang Provincial People′s Hospital, People′s Hospital of Hangzhou Medical College, Hangzhou 310014, China
Luo Kuangnan
Hangzhou Shengshi Technology, Co., Ltd, 311199, China
Mao Dewang
Department of Radiology, Zhejiang Provincial People′s Hospital, People′s Hospital of Hangzhou Medical College, Hangzhou 310014, China
