Computational system to create an entry file for replicating I-125 seeds simulating brachytherapy case studies using the MCNPX code

Leonardo da Silva Boia, Juraci P. R. Junior, Artur F. Menezes, Ademir X. Silva


Purpose: A computational system was developed for this paper in the C++ programming language, to create a 125I radioactive seed entry file, based on the positioning of a virtual grid (template) in voxel geometries, with the purpose of performing prostate cancer treatment simulations using the MCNPX code.

Methods: The system is fed with information from the planning system with regard to each seed’s location and its depth, and an entry file is automatically created with all the cards (instructions) for each seed regarding their cell blocks and surfaces spread out spatially in the 3D environment. The system provides with precision a reproduction of the clinical scenario for the MCNPX code’s simulation environment, thereby allowing the technique’s in-depth study.

Results and Conclusion: The preliminary results from this study showed that the lateral penumbra of uniform scanning proton beams was less sensitive In order to validate the computational system, an entry file was created with 88 125I seeds that were inserted in the phantom’s MAX06 prostate region with initial activity determined for the seeds at the 0.27 mCi value. Isodose curves were obtained in all the prostate slices in 5 mm steps in the 7 to 10 cm interval, totaling 7 slices. Variance reduction techniques were applied in order to optimize computational time and the reduction of uncertainties such as photon and electron energy interruptions in 4 keV and forced collisions regarding cells of interest. Through the acquisition of isodose curves, the results obtained show that hot spots have values above 300 Gy, as anticipated in literature, stressing the importance of the sources’ correct positioning, in which the computational system developed provides, in order not to release excessive doses in adjacent risk organs. The 144 Gy prescription curve showed in the validation process that it covers perfectly a large percentage of the volume, at the same time that it demonstrates a large decline for short distances.


Cite this article as: Boia LS, Junior J, Menezes AF, Silva AX. Computational system to create an entry file for replicating I-125 seeds simulating brachytherapy case studies using the MCNPX code. Int J Cancer Ther Oncol 2014; 2(2):02023.



C++ programming language; Brachytherapy; phantom MAX06; Voxel; MCNPX.

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INCA, Estimativa 2012. Available from

Pelowitz, DB. Ed. MCNPXTM User`s Manual. Version 2.5.0, Los Alamos National Laboratory Report LA-CP-05-0369 (2005).

Stroustrup B. The C++ Programming Language - Third Edition. Addison-Wesley; 1997.

Duggan DM. Improved radial dose function estimation using current version MCNP Monte-Carlo simulation: Model 6711 and ISC3500 125I brachytherapy sources. Appl Radiat Isot 2004; 61:1443-50.

Reis JP. Avaliações das aproximações utilizadas ao planejamento do tratamento de braquiterapia de próstata. Tese de Doutorado - UFRJ/COPPE/PEN, 2011.

Kramer R, Vieira JW, Khoury HJ, Lima FRA, Fuelle D. All about MAX: A male adult voxel phantom for Monte Carlo calculation in radiation protection dosimetry. Phys Med Biol 2008; 48:1239-62.

Zubal IG, Harrel CR, Smith EO, Smith AL, Krischlunas P. High resolution, MRI-based, segmented, computerized head phantom, The Zubal Phantom Data, Voxel-Based Anthropomorphic Phantoms. Available from

Kramer R, Khoury HJ, Vieira J W, Lima VJM. MAX06 and FAX06: Update of two adult human phantoms for radiation protection dosimetry. Phys Med Biol, 2006; 51: 3331-46.

Milian FM, Garcia F, Yoriyaz H, Siqueira PTD. Issac S. TOMO_MC programa para criação de INPUT FILES para o MCNPX a partir de modelos natômicos 3D. In: XIII Seminário de Iniciação Científica e 9ª Semana de Pesquisa e Pós-Graduação, 2007, Ilhéus. UESC.

Dev C++, 2005. GNU - General Public License, Version 4.9, 9.2.

Van Riper KA. MORITZ Geometry Tool User's Guide - Windows Version (Manual). White Rock Science (2008).

Amadei LPP. Evolução Bioquímica através de Medidas Seriadas de Antígeno Prostático Específico (PSA) de Pacientes Submetidos à raquiterapia com o Implante de Sementes de 125I no ratamento de Adenocarcinoma de Próstata, Tese (Doutorado em Medicina), Faculdade de Medicina da Universidade de São Paulo, Departamento de Radiologia Autarquia Associada à Universidade de São Paulo. (2008).

Yu Y, Anderson LL, Li Z, Mellenberg DE, Nath R, Schell MC, Waterman FM, Wu A, Blasko JC. Permanent prostate seed implant brachytherapy: report of the American Association of Physicists in Medicine Task Group No. 64. Med Phys 1999:26: 2054-76.


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