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SU‐GG‐T‐78: Influence of Material Heterogeneities for Brachytherapy Dose Calculations
Author(s) -
Rivard MJ,
Beaulieu L,
Mourtada F
Publication year - 2010
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3468466
Subject(s) - brachytherapy , formalism (music) , nuclear medicine , medicine , physics , library science , medical physics , computer science , radiation therapy , surgery , art , musical , visual arts
Purpose : To quantify the influence of material heterogeneities for brachytherapy dose calculations. Method and Materials : Current brachytherapy treatment planning systems (TPS) use the TG‐43 dose calculation formalism. This formalism uses the superposition principle with single‐source dose distributions in liquid water, and is used for all conventional brachytherapy sources (both low‐energy and high‐energy photon emitters). In the high‐energy regime, dosimetric sensitivity to media heterogeneities in comparison to water is less significant than for low‐energy sources. To quantify these effects as a function of photon energy, a series of Monte Carlo (MC) based radiation transport simulations was performed using the MCNP5 code. For simplicity and generalization, brachytherapy sources were approximated as point sources in spherical phantoms, with isotropic mono‐energetic photon‐emitting point sources to approximate photon energies from common radionuclides. The first simulation series was a homogeneous water phantom used as the reference geometry, and was compared to two different heterogeneous phantoms selected with consideration to photon energy. The low‐energy heterogeneous phantom used breast tissue for r≤3cm, cortical bone for 3.0