title: Absorbed dose calculations in a brachytherapy pelvic phantom using the Monte Carlo method.
abstract: Monte Carlo calculations of the absorbed dose at various points of a brachytherapy anthropomorphic phantom are presented. The phantom walls and internal structures are made of polymethylmethacrylate and its external shape was taken from a female Alderson phantom. A complete Fletcher-Green type applicator with the uterine tandem was fixed at the bottom of the phantom reproducing a typical geometrical configuration as that attained in a gynecological brachytherapy treatment. The dose rate produced by an array of five (137)Cs CDC-J type sources placed in the applicator colpostats and the uterine tandem was evaluated by Monte Carlo simulations using the code PENELOPE at three points: point A, the rectum, and the bladder. The influence of the applicator in the dose rate was evaluated by comparing Monte Carlo simulations of the sources alone and the sources inserted in the applicator. Differences up to 56% in the dose may be observed for the two cases in the planes including the rectum and bladder. The results show a reduction of the dose of 15.6%, 14.0%, and 5.6% in the rectum, bladder, and point A respectively, when the applicator wall and shieldings are considered.
authors.affiliation: Laboratório de Ciências Radiológicas, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, Maracanã, Rio de Janeiro RJ, Brazil. miroca_ven@yahoo.com
authors.forename: Miguel L
authors.initials: ML
authors.lastname: Rodríguez
authors.forename: Carlos E
authors.initials: CE
authors.lastname: deAlmeida
mesh_terms: D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods / Q000706:statistics & numerical data; D006801:Humans; D009010:Monte Carlo Method; D010388:Pelvis / Q000528:radiation effects*; D019047:Phantoms, Imaging; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation* / Q000379:methods / Q000706:statistics & numerical data; D020266:Radiotherapy, Conformal / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data