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

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

来源：Radiation Physics and Chemistry, 2017, 137: 29-32.

DOI：10.1016/j.radphyschem.2016.02.015

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

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.

• 出版日期2017-8
• 单位长春大学