The impact of MCS models and EFAC values on the dose simulation for a proton pencil beam

Shih Kuan Chen; Bing Hao Chiang; Chung Chi Lee; Chuan Jong Tung; Ji Hong Hong; Tsi Chian Chao

doi:10.1016/j.radphyschem.2016.02.015

The impact of MCS models and EFAC values on the dose simulation for a proton pencil beam

Shih Kuan Chen, Bing Hao Chiang, Chung Chi Lee, Chuan Jong Tung, Ji Hong Hong, Tsi Chian Chao^*

^*Corresponding author for this work

Department of Medical Imaging and Radiological Sciences

Research output: Contribution to journal › Journal Article › peer-review

1 Scopus citations

Abstract

The Multiple Coulomb Scattering (MCS) model plays an important role in accurate MC simulation, especially for small field applications. The Rossi model is used in MCNPX 2.7.0, and the Lewis model in Geant4.9.6.p02. These two models may generate very different angular and spatial distributions in small field proton dosimetry. Beside angular and spatial distributions, step size is also an important issue that causes path length effects. The Energy Fraction (EFAC) value can be used in MCNPX 2.7.0 to control step sizes of MCS. In this study, we use MCNPX 2.7.0, Geant4.9.6.p02, and one pencil beam algorithm to evaluate the effect of dose deposition because of different MCS models and different EFAC values in proton disequilibrium situation. Different MCS models agree well with each other under a proton equilibrium situation. Under proton disequilibrium situations, the MCNPX and Geant4 results, however, show a significant deviation (up to 43%). In addition, the path length effects are more significant when EFAC is equal to 0.917 and 0.94 in small field proton dosimetry, and using a 0.97

Original language	English
Pages (from-to)	29-32
Number of pages	4
Journal	Radiation Physics and Chemistry
Volume	137
DOIs	https://doi.org/10.1016/j.radphyschem.2016.02.015
State	Published - 08 2017

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Publisher Copyright:
© 2017 Elsevier Ltd

Keywords

Monte Carlo
Multiple Coulomb scattering
Path length correction
Proton therapy
Small field

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10.1016/j.radphyschem.2016.02.015

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title = "The impact of MCS models and EFAC values on the dose simulation for a proton pencil beam",

abstract = "The Multiple Coulomb Scattering (MCS) model plays an important role in accurate MC simulation, especially for small field applications. The Rossi model is used in MCNPX 2.7.0, and the Lewis model in Geant4.9.6.p02. These two models may generate very different angular and spatial distributions in small field proton dosimetry. Beside angular and spatial distributions, step size is also an important issue that causes path length effects. The Energy Fraction (EFAC) value can be used in MCNPX 2.7.0 to control step sizes of MCS. In this study, we use MCNPX 2.7.0, Geant4.9.6.p02, and one pencil beam algorithm to evaluate the effect of dose deposition because of different MCS models and different EFAC values in proton disequilibrium situation. Different MCS models agree well with each other under a proton equilibrium situation. Under proton disequilibrium situations, the MCNPX and Geant4 results, however, show a significant deviation (up to 43%). In addition, the path length effects are more significant when EFAC is equal to 0.917 and 0.94 in small field proton dosimetry, and using a 0.97",

keywords = "Monte Carlo, Multiple Coulomb scattering, Path length correction, Proton therapy, Small field",

author = "Chen, {Shih Kuan} and Chiang, {Bing Hao} and Lee, {Chung Chi} and Tung, {Chuan Jong} and Hong, {Ji Hong} and Chao, {Tsi Chian}",

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year = "2017",

month = aug,

doi = "10.1016/j.radphyschem.2016.02.015",

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AU - Chen, Shih Kuan

AU - Chiang, Bing Hao

AU - Lee, Chung Chi

AU - Tung, Chuan Jong

AU - Hong, Ji Hong

AU - Chao, Tsi Chian

PY - 2017/8

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N2 - The Multiple Coulomb Scattering (MCS) model plays an important role in accurate MC simulation, especially for small field applications. The Rossi model is used in MCNPX 2.7.0, and the Lewis model in Geant4.9.6.p02. These two models may generate very different angular and spatial distributions in small field proton dosimetry. Beside angular and spatial distributions, step size is also an important issue that causes path length effects. The Energy Fraction (EFAC) value can be used in MCNPX 2.7.0 to control step sizes of MCS. In this study, we use MCNPX 2.7.0, Geant4.9.6.p02, and one pencil beam algorithm to evaluate the effect of dose deposition because of different MCS models and different EFAC values in proton disequilibrium situation. Different MCS models agree well with each other under a proton equilibrium situation. Under proton disequilibrium situations, the MCNPX and Geant4 results, however, show a significant deviation (up to 43%). In addition, the path length effects are more significant when EFAC is equal to 0.917 and 0.94 in small field proton dosimetry, and using a 0.97

AB - The Multiple Coulomb Scattering (MCS) model plays an important role in accurate MC simulation, especially for small field applications. The Rossi model is used in MCNPX 2.7.0, and the Lewis model in Geant4.9.6.p02. These two models may generate very different angular and spatial distributions in small field proton dosimetry. Beside angular and spatial distributions, step size is also an important issue that causes path length effects. The Energy Fraction (EFAC) value can be used in MCNPX 2.7.0 to control step sizes of MCS. In this study, we use MCNPX 2.7.0, Geant4.9.6.p02, and one pencil beam algorithm to evaluate the effect of dose deposition because of different MCS models and different EFAC values in proton disequilibrium situation. Different MCS models agree well with each other under a proton equilibrium situation. Under proton disequilibrium situations, the MCNPX and Geant4 results, however, show a significant deviation (up to 43%). In addition, the path length effects are more significant when EFAC is equal to 0.917 and 0.94 in small field proton dosimetry, and using a 0.97

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ER -

The impact of MCS models and EFAC values on the dose simulation for a proton pencil beam

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Keywords

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