Letter response relatively to the paper entitled: Assessment of the uterine dose in digital mammography and digital breast tomosynthesis

Abstract

We thank A. Mackenzie et al. for their interest in our work 1 Cepeda Martins R. Di Maria S. Afonso J. Pereira M. Pereira J. Vaz P. Assessment of the uterine dose in digital mammography and digital breast tomosynthesis. Radiography. 2022; 28: 333-339https://doi.org/10.1016/j.radi.2021.09.002 Abstract Full Text Full Text PDF PubMed Scopus (1) Google Scholar and for sharing their views in a Letter to the Editor. 2 Mackenzie A. Borrelli C.D. Under-estimation of uterine dose in medio-lateral oblique by Martins et al. Radiography. 2022 May; 28: 572-573https://doi.org/10.1016/j.radi.2022.02.002 Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar Going to the specific issues raised by Mackenzie et al. 2 Mackenzie A. Borrelli C.D. Under-estimation of uterine dose in medio-lateral oblique by Martins et al. Radiography. 2022 May; 28: 572-573https://doi.org/10.1016/j.radi.2022.02.002 Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar , we would like to remark: i)Mackenzie et al. 2 Mackenzie A. Borrelli C.D. Under-estimation of uterine dose in medio-lateral oblique by Martins et al. Radiography. 2022 May; 28: 572-573https://doi.org/10.1016/j.radi.2022.02.002 Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar suggest, and we agree, that our projection view setup is not the most frequent view used for screening purposes, even if it is clinically used. The MLO view we used is the same of MLO but rotated by 90° (specular view). Mackenzie et al. 2 Mackenzie A. Borrelli C.D. Under-estimation of uterine dose in medio-lateral oblique by Martins et al. Radiography. 2022 May; 28: 572-573https://doi.org/10.1016/j.radi.2022.02.002 Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar suggest that the name of our view should be latero-medial oblique (LMO), as reported by P. Hogg et al. 3 Hogg P. Kelly J. Mercer C. Digital Mammography: a holistic approach. Springer, 2015 Crossref Scopus (18) Google Scholar . However, Reis et al. 4 Reis C. Pascoal A. Sakellaris T. Koutalonis M. Quality assurance and quality control in mammography: a review of available guidance worldwide. Insights Imaging. 2013; 4: 539-553 Crossref PubMed Scopus (22) Google Scholar suggest that noticeable variations exist in mammography protocols. In the American College of Radiology (ACR) terminology, LMO is defined as the lateromedial oblique view performed with the X-ray beam directed from the lower-outer to the upper-inner aspect of the breast (the exact reverse of MLO and not the view we used). The view we used, is referred to in ACR formalism as “Superolateral to inferomedial Oblique” (SIO). 5 Andolina V.F. Lillé S.L. Mammographic positioning (chapter 7). in: Mammography Imaging: a practical guide. 3rd ed. Wolters Kluwer, 2010 Google Scholar In order to avoid confusion, and because this is not the focus of our study, we used the formalism MLO to only indicate the different geometry setup between the two views considered in our study. ii)Mackenzie et al. 2 Mackenzie A. Borrelli C.D. Under-estimation of uterine dose in medio-lateral oblique by Martins et al. Radiography. 2022 May; 28: 572-573https://doi.org/10.1016/j.radi.2022.02.002 Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar state that, “the uterine dose will be expected to be considerably larger than those described in this paper in the standard MLO view”. This is surprising, speculative, and not supported by any experimental data. Please note that in each view position, the primary beam is directed to the examined breast, whereas all the radiation around the mammography system is typically described by scatter radiation produced mainly by the detector assembly, 6 Yang K. Li X. Liu B. Scatter radiation intensities around a clinical digital breast tomosynthesis unit and the impact on radiation shielding considerations. Med Phys. 2016; 43: 1096-1110 Crossref PubMed Scopus (5) Google Scholar provided the patient positioning is correctly performed. Mackenzie et al. 2 Mackenzie A. Borrelli C.D. Under-estimation of uterine dose in medio-lateral oblique by Martins et al. Radiography. 2022 May; 28: 572-573https://doi.org/10.1016/j.radi.2022.02.002 Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar cite the computational work of Sechopoulos et al., 7 Sechopoulos I. Suryanaranan S. Vedantham S. D'Orsi C.J. Karellas A. Radiation dose to organs and tissues from mammography: Monte Carlo and phantom study. Radiology. 2008; 246: 434-443 Crossref PubMed Scopus (69) Google Scholar performed with a mathematical phantom, to remark that the absorbed dose to the uterus in MLO could be up to 100 times greater than in CC view, whereas in another computational mammography study, 8 Baptista M. Di Maria S. Sbarros S. Figueira C. Sarmento M. Orvalho L. et al. Dosimetric characterization and organ dose assessment in digital breast tomosynthesis: measurements and Monte Carlo simulations using voxel phantoms. Med Phys. 2015; 42: 3788-3800 Crossref PubMed Scopus (15) Google Scholar with an anthropomorphic voxel phantom, almost no relevant uterine absorbed doses were reported for oblique irradiation angles. There is also a study reporting the experimental scatter distribution in mammography 6 Yang K. Li X. Liu B. Scatter radiation intensities around a clinical digital breast tomosynthesis unit and the impact on radiation shielding considerations. Med Phys. 2016; 43: 1096-1110 Crossref PubMed Scopus (5) Google Scholar which reported that the maximum scatter dose distribution measured was greater in CC than in MLO (see Table II of Yang et al. 6 Yang K. Li X. Liu B. Scatter radiation intensities around a clinical digital breast tomosynthesis unit and the impact on radiation shielding considerations. Med Phys. 2016; 43: 1096-1110 Crossref PubMed Scopus (5) Google Scholar ). According to Figure 9 (bottom row) of Yang et al.‘s study, 6 Yang K. Li X. Liu B. Scatter radiation intensities around a clinical digital breast tomosynthesis unit and the impact on radiation shielding considerations. Med Phys. 2016; 43: 1096-1110 Crossref PubMed Scopus (5) Google Scholar for an MLO setup (30° angulation) the maximum scatter contribution is just in the middle below the detector. Given this issue and given that more than 70% of the scatter distribution depends only on the image detector assembly, 6 Yang K. Li X. Liu B. Scatter radiation intensities around a clinical digital breast tomosynthesis unit and the impact on radiation shielding considerations. Med Phys. 2016; 43: 1096-1110 Crossref PubMed Scopus (5) Google Scholar it may be anticipated that the scatter radiation contribution for the MLO or specular view could be of the same order of magnitude.