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Validation and Application of a Commercial Proton Monte Carlo Pencil Beam Scanning Treatment Planning System

S Huang1*, A Maslowski2 , P Hiltunen2 , L Lin3 , (1) Memorial Sloan Kettering Cancer Center, New York, NY, (2) Varian Medical Systems, Palo Alto, CA, (3) Emory Proton Therapy Center, Atlanta, GA


(Sunday, 7/14/2019)  

Room: ePoster Forums

Purpose: To validate a commercial and fast Monte Carlo code-AcurosPT 13.7.20, (Varian Medical Systems, Palo Alto, CA), and assess its application in clinical settings.

Methods: With improved modeling of multiple Coulomb scattering (MCS) and proton slowing down, AcurosPT was validated using water and tissue-mimicking IROC lung phantom measurements as well as benchmarked with the general purpose Monte Carlo TOPAS. Then a comparative analysis between AcurosPT and analytical dose calculation (ADC) was performed for 25 patients with 5 patients per disease site (including liver, pelvis, brain, head-and-neck and lung).

Results: Updated AcurosPT 13.7.20 has fixed the issue of overestimation of the MCS and halo, which led to unacceptable deviation for treatments with range shifter and large air gaps in the old version. The difference between AcurosPT 13.7.20 and measurements is within 2% for output factors for both without and with range shifters. Comparison between AcursoPT and TOPAS showed less than 1.7% difference for all the dosimetric indices/TCP values and larger than 98.6% for the 3%/3mm 3D gamma-index passing rate of the target. Through comparison between ADC and AcurosPT for patient dose verification, dose degradation increases from liver to lung, as the degree of tissue heterogeneity increases.

Conclusion: We presented a comprehensive evaluation of a newly upgraded commercial MC dose calculation algorithm, the AcurosPT 13.7.20, for use in PBS proton therapy. The performance of AcurosPT 13.7.20 was validated against both measurements and TOPAS simulations in a variety of homogenous and heterogeneous phantom and also patient’s condition. The AcurosPT can provide acceptable accuracy when range shifter is employed and for heterogeneous media. Using an independent and fast MC code, we can provide additional quality assurance and more efficient patient treatment workflow.

Funding Support, Disclosures, and Conflict of Interest: This project is supported by a grant under the master agreement between University of Pennsylvania and Varian Medical Systems.


Monte Carlo, Protons


TH- External Beam- Particle therapy: Proton therapy - computational dosimetry-Monte Carlo

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