To compare the radiation dose and diagnostic efficiency of digital breast tomosynthesis (DBT) and full-field digital mammography (FFDM) under different position combinations.

A retrospective analysis was performed in 419 patients (837 breasts) who underwent both DBT and FFDM in the surgical clinic of Dahua Hospital, Xuhui District, Shanghai from May 2018 to January 2022. According to different photographic combinations, the patients were divided into five groups: group A, FFDM [(craniocaudal, CC) + (mediolateral oblique, MLO)]; group B, FFDM (CC) + DBT (MLO); group C, FFDM (MLO) + DBT (CC); group D, DBT (CC + MLO); group F, FFDM (CC + MLO) + DBT (CC + MLO). The final pathological results were used as the diagnostic basis. One-way analysis of variance and post-hoc test were used to compare the radiation dose and detection rate of different imaging features among five groups. The receiver operating characteristic (ROC) curves of the five groups were drawn for the diagnostic efficiency of malignant lesions, the non-parametric test was used for the comparison of the area under the curve between groups, and the Delong test was used for pairwise comparison.

There was a significant difference in the radiation dose among the five groups [group A: (1.975±0.752) mGy; group B: (3.039±1.173) mGy; group C: (2.998±1.059) mGy; group D: (4.023±1.482) mGy; group F: (6.037±2.154) mGy; F=996.373, P<0.001]. Except no significant difference between group B and group C, pairwise comparison showed a significant difference between groups (all P<0.001). A total of 45 malignant lesions were found in 837 breasts. The areas under the ROC curve were 0.913 (95%CI: 0.892-0.931), 0.979 (95%CI: 0.966-0.987), 0.983 (95%CI: 0.972-0.991), 0.982 (95%CI: 0.970-0.990) and 0.986 (95%CI: 0.976-0.993) in groups A-F, respectively, indicating a significant differences between groups (Z=114.744, P<0.001). There were significant differences in the area under the ROC curve between group A and group B/C/D/F (Z=2.358, 2.497, 2.442, 2.607, P=0.018, 0.013, 0.015, 0.009), between group B and group C/F (Z=2.287, 2.338, P=0.022, 0.019), between group D and group F (Z=3.096, P=0.002). The diagnostic sensitivity and specificity were 75.56% and 6.46% in group A, 91.11% and 95.45% in group B, 91.11% and 96.21% in group C, 93.33% and 95.58% in group D, 93.33% and 95.71% in group F.

The combination of FFDM (MLO) + DBT (CC) shows the advantage of low radiation dose without compromising diagnostic performance.