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Purpose: Use of mechanical imaging (MI) as complementary to digital mammography (DM), or in simultaneous digital breast tomosynthesis (DBT) and MI - DBTMI, has demonstrated the potential to increase the specificity of breast cancer screening and reduce unnecessary biopsies compared with DM. The aim of this study is to investigate the increase in the radiation dose due to the presence of an MI sensor during simultaneous image acquisition when automatic exposure control is used. Approach: A radiation dose study was conducted on clinically available breast imaging systems with and without an MI sensor present. Our estimations were based on three approaches. In the first approach, exposure values were compared in paired clinical DBT and DBTMI acquisitions in 97 women. In the second approach polymethyl methacrylate (PMMA) phantoms of various thicknesses were used, and the average glandular dose (AGD) values were compared. Finally, a rectangular PMMA phantom with a 45 mm thickness was used, and the AGD values were estimated based on air kerma measurements with an electronic dosemeter. Results: The relative increase in exposure estimated from digital imaging and communications in medicine headers when using an MI sensor in clinical DBTMI was 11.9 % ± 10.4 . For the phantom measurements of various thicknesses of PMMA, the relative increases in the AGD for DM and DBT measurements were, on average, 10.7 % ± 3.1 and 11.4 % ± 3.0 , respectively. The relative increase in the AGD using the electronic dosemeter was 11.2 % ± < 0.001 in DM and 12.2 % ± < 0.001 in DBT. The average difference in dose between the methods was 11.5 % ± 3.3 . Conclusions: Our measurements suggest that the use of simultaneous breast radiography and MI increases the AGD by an average of 11.5 % ± 3.3 . The increase in dose is within the acceptable values for mammography screening recommended by European guidelines.
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Background Analysis of how digital breast tomosynthesis (DBT) screening affects consecutive screening performance is important to estimate its future value in screening. Purpose To evaluate whether DBT contributes to early detection of breast cancer by assessing cancer detection rates (CDRs), including the fraction of invasive cancers and cancer subtypes in consecutive routine digital mammography (DM). Materials and Methods The paired prospective Malmö Breast Tomosynthesis Screening Trial (MBTST) was performed between January 2010 and February 2015. Participating women underwent one-view DBT and two-view DM at one screening occasion. In this secondary analysis, women were followed up through their first (DM1) and second (DM2) consecutive two-view DM screening rounds after MBTST participation. Cancer diagnoses were identified by referencing records. A logistic regression model, adjusted for age, was used to calculate the odds of luminal A-like cancers with use of the MBTST as reference. Results There were 14 848 final participants in the MBTST (median age, 57 years [IQR, 49-65 years]). Of those, 12 876 women were screened in DM1 (median age, 58 years [IQR, 50-66 years]) and 10 883 were screened in DM2 (median age, 59 years [IQR, 51-67 years]). Compared with CDRs in the trial of 6.5 of 1000 women (95% CI: 5.2, 7.9) for DM and 8.7 of 1000 women (95% CI: 7.3, 10.3) for DBT, the CDR was lower in DM1 (4.6 of 1000 women [95% CI: 3.6, 5.9]) and DM2 (5.3 of 1000 women [95% CI: 4.1, 6.9]). The proportion of invasive cancers was 84.9% (118 of 139 cancers) in the MBTST; the corresponding numbers were 66% (39 of 59 cancers) for DM1 and 83% (50 of 60 cancers) for DM2. The odds of luminal A-like cancers were lower in DM1 at 0.28 (95% CI: 0.12, 0.66 [P = .004]) but not in DM2 at 0.80 (95% CI: 0.40, 1.58 [P = .52]) versus screening in the MBTST. Conclusion CDR and the fraction of invasive cancers were lower in DM1 and then increased in DM2 following the MBTST, indicating earlier cancer detection mainly due to increased detection of luminal A-like cancers in DBT screening. Clinical trials registration no. NCT01091545 © RSNA, 2024 See also the editorial by Hooley and Philpotts in this issue.