RESUMO
Objective To compare the difference between volume computed tomography dose index (CTDIvol) and size-specific dose estimates (SSDE) in evaluating the radiation dose of abdominal CT scan.Methods Abdominal CT scan were performed on 180 patients with a Philips 256-slices spiral CT.The anterior-posterior dimension (AP) and lateral dimension (LAT) of each patients were measured at the level of left renal vein, and the effective diameter (ED) and SSDE were calculated with recorded CTDIvol Patients were categorized into 3 groups depending on body mass index (BMI): group A, BMI ＜ 20.0 kg/m2;group B, 20.0-24.9 kg/m2;group C, BMI ＞ 24.9 kg/m2.The differences between CTDIvoland SSDE of 180 patients and three different BMI groups were compared respectively.Results There was a significant difference between CTDIvol and SSDE of the 180 patients (t =-13.354, P ＜ 0.01), CTDIvol and SSDE were (9.91 ± 2.91) and (14.01 ± 2.82) mGy, respectively.For group A, CTDIvol and SSDE were (7.96 ± 1.83) and (12.83 ± 2.52) mGy, respectively (t =-8.417, P ＜ 0.01).Group B, CTDIvol and SSDE were (9.28 ± 1.76) and (13.62 ±2.18) mGy, respectively (t =-15.051, P ＜ 0.01).Group C, CTDIvol and SSDE were (12.19 ± 3.65) and (15.39 ± 3.47) mGy, respectively (t =-4.535, P ＜ 0.01).In addition, the mean percentage values of difference between CTDIvol and SSDE for the three groups were 62.83％, 47.80％, 28.40％, respectively, which meant CTDIvol underestimated the radiation dose compared to SSDE.With the BMI increasing, the values of difference between CTDIvol and SSDE decreased.Conclusions SSDE can be used to estimate the radiation dose of abdominal CT scan for a given size person.