<abstract xml:lang="en" xmlns="http://www.w3.org/1999/xhtml">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.</abstract>

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.

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

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

Faculdade de Ciencias e Tecnologia da Universidade Nova de Lisboa, Portugal

Escola Superior de Tecnologia da Saude de Lisboa, Lisboa, Portugal

Faculdade de Ciencias Medicas, Universidade Nova de Lisboa, Portugal

Polish Journal of Medical Physics and Engineering

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...

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

Published Online: Apr 14, 2009

Page range: 163 - 182

DOI: https://doi.org/10.2478/v10013-008-0014-0

Keywords
surface dose, build-up dose, MLC, IMRT, Monte Carlo

This content is open access.

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

Published Online: Apr 14, 2009

Page range: 163 - 182

DOI: https://doi.org/10.2478/v10013-008-0014-0

Keywordssurface dose, build-up dose, MLC, IMRT, Monte Carlo

This content is open access.

Keywords
surface dose, build-up dose, MLC, IMRT, Monte Carlo