title: Influence of breast composition and interseed attenuation in dose calculations for post-implant assessment of permanent breast 103Pd seed implant.
abstract: The impact of tissue heterogeneity and interseed attenuation is studied in post-implant evaluation of five clinical permanent breast (103)Pd seed implants using the Monte Carlo (MC) dose calculation method. Dose metrics for the target (PTV) as well as an organ at risk (skin) are used to visualize the differences between a TG43-like MC method and more accurate MC methods capable of considering the breast tissue heterogeneity as well as the interseed attenuation. PTV dose is reduced when using a breast tissue model instead of water in MC calculations while the dose to the skin is increased. Furthermore, we investigate the effect of varying the glandular/adipose proportion of the breast tissue on dose distributions. The dose to the PTV (skin) decreases (increases) with the increasing adipose proportion inside the breast. In a complete geometry and compared to a TG43-like situation, the average PTV D(90) reduction varies from 3.9% in a glandular breast to 35.5% when the breast consists entirely of adipose. The skin D(10) increases by 28.2% in an entirely adipose breast. The results of this work show the importance of an accurate and patient-dependent breast tissue model to be used in the dosimetry for this kind of low energy implant.
authors.affiliation: Département de Radio-Oncologie et Centre de recherche en cancérologie de l'Université Laval, Centre Hospitalier Universitaire de Québec, 11 Côte du Palais, Québec, QC G1R 2J6, Canada.
authors.forename: Hossein
authors.initials: H
authors.lastname: Afsharpour
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Pignol
authors.forename: Brian
authors.initials: B
authors.lastname: Keller
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Carrier
authors.forename: Brigitte
authors.initials: B
authors.lastname: Reniers
authors.forename: Frank
authors.initials: F
authors.lastname: Verhaegen
authors.forename: Luc
authors.initials: L
authors.lastname: Beaulieu
mesh_terms: D000273:Adipose Tissue / Q000528:radiation effects; D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods; D001940:Breast / Q000503:physiopathology* / Q000528:radiation effects*; D003198:Computer Simulation; D005260:Female; D006801:Humans; D009010:Monte Carlo Method; D010165:Palladium / Q000627:therapeutic use*; D011868:Radioisotopes / Q000627:therapeutic use*; D011874:Radiometry / Q000379:methods; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012984:Software
chemical_list: D011868:Radioisotopes; D010165:Palladium