Assesing multileaf collimator effect on the build-up region using Monte Carlo method

• Authors: M. Moreno , N. Teixeira , A. Jesus , G. Mora
• Languages of publication: EN

Abstracts

EN

Previous Monte Carlo studies have investigated the multileaf collimator (MLC) contribution to the build-up region for fields in which the MLC leaves were fully blocking the openings defined by the collimation jaws. In the present work, we investigate the same effect but for symmetric and asymmetric MLC defined field sizes (2×2, 4×4, 10×10 and 3×7 cm2). A Varian 2100C/D accelerator with 120-leaf MLC is accurately modeled for a 6MV photon beam using the BEAMnrc/EGSnrc code.Our results indicate that particles scattered from accelerator head and MLC are responsible for the increase of about 7% on the surface dose when comparing 2×2 and 10×10 cm2 fields. We found that the MLC contribution to the total build-up dose is about 2% for the 2×2 cm2 field and less than 1% for the largest fields.

Keywords

EN

surface dose; build-up dose; MLC; IMRT; Monte Carlo

• Publisher: Versita
• Journal: Polish Journal of Medical Physics And Engineering
• Year: 2008
• Volume: 14
• Issue: 3
• Pages: 163-182

Dates

published

1 - 1 - 2008

online

14 - 4 - 2009

Contributors

author

M. Moreno

author

N. Teixeira

author

A. Jesus

author

G. Mora

• Centro de Fisica Nuclear da Universidade de Lisboa, Lisboa, Portugal

References

• Heath E, Seuntjens J. Development and validation of a BEAMnrc component module for accurate Monte Carlo modelling of the Varian dynamic Millenium multileaf collimator. Phys Med Biol. 2003; 48: 4045-4063.[WoS][Crossref]
• Jang SY, Vassiliev ON, Liu HH, Mohan R, Siebers JV. Development and commissioning of a multileaf collimator model in Monte Carlo dose calculations for intensity-modulated radiation therapy. Med Phys. 2006; 33(3): 770-781.[Crossref][PubMed]
• Kim JO, Siebers JV, Keall PJ, Arnfield MR, Mohan R. A Monte Carlo study of radiation transport through multileaf collimators. Med Phys. 2001; 28: 2497-2506.[Crossref][PubMed]
• Mora GM, Maio A, Rogers DWO. Monte Carlo Simulation of a Typical 60Co Therapy Source. Med Phys. 1999; 26: 2494-2502.[Crossref]
• Rogers DWO, Walters B, Kawrakow I. BEAMnrc Users Manual. Ottawa: National Research Council of Canada; 2005. Report PIRS-0509(A)revK.
• Walters B, Kawrakow I, Rogers DWO. DOSXYZnrc Users Manual. Ottawa: National Research Council of Canada; 2005. Report PIRS-794revB.

Identifiers

DOI

10.2478/v10013-008-0014-0