A Monte Carlo model for mean glandular dose evaluation in spot compression mammography

• Type of Material: Article
• Authors: Antonio Sarno, University of Naples Federico II; David R. Dance, Royal Surrey County Hospital; Ruben E. van Engen, Dutch Reference Centre for Screening (LRCB); Kenneth C. Young, Royal Surrey County Hospital; Paolo Russo, University of Naples Federico II; Francesca Di Lillo, University of Naples Federico II; Giovanni Mettivier, University of Naples Federico II; Kristina Bliznakova, Technical University Varna; Baowei Fei, Emory University; Ioannis Sechopoulos, Dutch Reference Centre for Screening (LRCB)
• Language: English
• Date: 2017-07-01
• Publisher: Wiley
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2017 American Association of Physicists in Medicine.
• Final Published Version (URL): http://dx.doi.org/10.1002/mp.12339
• Title of Journal or Parent Work: Medical Physics
• ISSN: 0094-2405
• Volume: 44
• Issue: 7
• Start Page: 3848
• End Page: 3860
• Grant/Funding Information: This work was supported in part by the MaXIMA project H2020-TWINN-2015 (grant no. 692097) (KB, PR, GM, AS, FDL), and by the INFN (AS, PR, GM, FDL).; Work supported in part by grants CA163746 (IS), CA181171 (IS), CA176684 (BF) and CA156775 (BF) from the National Cancer Institute, National Institutes of Health, and IIR13262248 (IS) from the Susan G. Komen Foundation.; The contribution of DRD was funded as part of the OPTIMAM2 project which is funded by Cancer Research UK (grant number: C30682/A17321).
• Keywords: RADIATION; Life Sciences & Biomedicine; Science & Technology; BREAST COMPUTED-TOMOGRAPHY; magnification mammography; Radiology, Nuclear Medicine & Medical Imaging; mean glandular dose; MAGNIFICATION MAMMOGRAPHY; UK; CONVERSION FACTORS; spot compression; DGN COEFFICIENTS; mammography; X-RAY-SPECTRA; DOSIMETRY PROTOCOLS
• Research Categories: Health Sciences, Medicine and Surgery; Engineering, Biomedical; Biophysics, Medical

Abstract

Purpose: To characterize the dependence of normalized glandular dose (DgN) on various breast model and image acquisition parameters during spot compression mammography and other partial breast irradiation conditions, and evaluate alternative previously proposed dose-related metrics for this breast imaging modality. Methods: Using Monte Carlo simulations with both simple homogeneous breast models and patient-specific breasts, three different dose-related metrics for spot compression mammography were compared: the standard DgN, the normalized glandular dose to only the directly irradiated portion of the breast (DgNv), and the DgN obtained by the product of the DgN for full field irradiation and the ratio of the mid-height area of the irradiated breast to the entire breast area (DgNM). How these metrics vary with field-of-view size, spot area thickness, x-ray energy, spot area and position, breast shape and size, and system geometry was characterized for the simple breast model and a comparison of the simple model results to those with patient-specific breasts was also performed. Results: The DgN in spot compression mammography can vary considerably with breast area. However, the difference in breast thickness between the spot compressed area and the uncompressed area does not introduce a variation in DgN. As long as the spot compressed area is completely within the breast area and only the compressed breast portion is directly irradiated, its position and size does not introduce a variation in DgN for the homogeneous breast model. As expected, DgN is lower than DgNv for all partial breast irradiation areas, especially when considering spot compression areas within the clinically used range. DgNMunderestimates DgN by 6.7% for a W/Rh spectrum at 28 kVp and for a 9 × 9 cm2compression paddle. Conclusion: As part of the development of a new breast dosimetry model, a task undertaken by the American Association of Physicists in Medicine and the European Federation of Organizations of Medical Physics, these results provide insight on how DgN and two alternative dose metrics behave with various image acquisition and model parameters.