Feasibility study for calculating size-specific dose estimates based on weight and body mass index in CT abdomen-pelvic examination of adult population
10.3760/cma.j.issn.0254-5098.2020.07.011
- VernacularTitle:基于体重和体质量指数计算腹盆CT体型特异性剂量估算值的可行性
- Author:
Jian XU
1
;
Xiangquan WANG
;
Panfeng YANG
;
Yelei XIE
;
Kuangnan LUO
;
Dewang MAO
Author Information
1. 浙江省人民医院 杭州医学院附属人民医院放射科 310014
- From:
Chinese Journal of Radiological Medicine and Protection
2020;40(7):549-553
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To explore the feasibility for taking weight and body mass index (BMI) to calculate the size-specific dose estimate (SSDE) in abdomen-pelvis CT examination.Methods:512 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 (SSDE weight, SSDE BMI), 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 SSDE weightand SSDE BMI were calculated, respectively. Results:No statistically significant correlation between age and d w ( P>0.05) was shown, but weak correlation between height and dw( r=0.260, P<0.05), strong correlation between either weight or BMI with dw( r=0.879, 0.851, P<0.05). Two regression equations were described as dw=13.808+ 0.184×weight, dw=11.142+ 0.618×BMI. The mean SSDE, SSDE weight and SSDE BMI 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 SSDE weight and SSDE BMI 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/m 2;1.92% and 2.06% for those with 18.5 kg/m 2≤BMI<24.0 kg/m 2;2.57% and 1.57% for those with 24 kg/m 2≤BMI<28.0 kg/m 2;3.28% and -1.36% for those with BMI≥28.0 kg/m 2. The averaged root-mean-square errors in SSDE weight and SSDE BMI 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. Conclusions:Weight 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.
