TOPAS Simulation of the Mevion S250 compact proton therapy unit.

Michael Prusator,Salahuddin Ahmad,Yong Chen

doi:10.1002/acm2.12077

Abstract

As proton therapy becomes increasingly popular, so does the need for Monte Carlo simulation studies involving accurate beam line modeling of proton treatment units. In this study, the 24 beam configurations of the Mevion S250 proton therapy system installed recently at our institution were modeled using the TOolkit for PArticle Simulation (TOPAS) code. Pristine Bragg peak, spread out Bragg peak (SOBP), and lateral beam profile dose distributions were simulated and matched to the measurements taken during commissioning of the unit. Differences in the range for all Percent Depth Dose (PDD) curves between measured and simulated data agreed to within 0.1 cm. For SOBP scans, the SOBP widths all agreed to within 0.3 cm. With regards to lateral beam profile comparisons between the measured and simulated data, the penumbras differed by less than 1 mm and the flatness differed by less than 1% in nearly all cases. This study shows that Monte Carlo simulation studies involving the Mevion S250 proton therapy unit can be a viable tool in commissioning and verification of the proton treatment planning system.

Highlights

Success in radiation therapy is dependent on maximization of the tumor control probability while minimizing the normal tissue complication probability
Monte Carlo simulation has traditionally been shown as a prominent method for conducting various research topics that include dosimetric, linear energy transfer (LET), and commissioning studies.[6,7,8]
In a study done by Paganetti et al, it was shown that the modeling of the IBA proton treatment head at the Northeast Proton Therapy Center resulted in simulated data matching with measured beam data within millimeter accuracy for beam range and 3 mm for spread out Bragg peak (SOBP) width.[9]

Summary

Introduction

Success in radiation therapy is dependent on maximization of the tumor control probability while minimizing the normal tissue complication probability. In order for the full potential of proton therapy to be utilized, there is a need for an accurate dose calculation in proton treatment plans. Monte Carlo simulation has traditionally been shown as a prominent method for conducting various research topics that include dosimetric, linear energy transfer (LET), and commissioning studies.[6,7,8] In a study done by Paganetti et al, it was shown that the modeling of the IBA proton treatment head at the Northeast Proton Therapy Center resulted in simulated data matching with measured beam data within millimeter accuracy for beam range and 3 mm for SOBP width.[9] This acceptable tolerance helps generation of detailed simulated beam data for use in commissioning of a treatment planning system.[10] Monte Carlo simulation has been used to calculate the risk of secondary cancer due to neutron exposure occurring

Methods

Results

Conclusion