title: A benchmarking method to evaluate the accuracy of a commercial proton monte carlo pencil beam scanning treatment planning system.
abstract: AcurosPT is a Monte Carlo algorithm in the Eclipse 13.7 treatment planning system, which is designed to provide rapid and accurate dose calculations for proton therapy. Computational run-time in minimized by simplifying or eliminating less significant physics processes. In this article, the accuracy of AcurosPT was benchmarked against both measurement and an independent MC calculation, TOPAS. Such a method can be applied to any new MC calculation for the detection of potential inaccuracies. To validate multiple Coulomb scattering (MCS) which affects primary beam broadening, single spot profiles in a Solidwater®phantom were compared for beams of five selected proton energies between AcurosPT, measurement and TOPAS. The spot Gaussian sigma in AcurosPT was found to increase faster with depth than both measurement and TOPAS, suggesting that the MCS algorithm in AcurosPT overestimates the scattering effect. To validate AcurosPT modeling of the halo component beyond primary beam broadening, field size factors (FSF) were compared for multi-spot profiles measured in a water phantom. The FSF for small field sizes were found to disagree with measurement, with the disagreement increasing with depth. Conversely, TOPAS simulations of the same FSF consistently agreed with measurement to within 1.5%. The disagreement in absolute dose between AcurosPT and measurement was smaller than 2% at the mid-range depth of multi-energy beams. While AcurosPT calculates acceptable dose distributions for typical clinical beams, users are cautioned of potentially larger errors at distal depths due to overestimated MCS and halo implementation.
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Liyong
authors.initials: L
authors.lastname: Lin
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Sheng
authors.initials: S
authors.lastname: Huang
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Minglei
authors.initials: M
authors.lastname: Kang
authors.affiliation: Varian Medical Systems, Palo Alto, California, USA.
authors.forename: Petri
authors.initials: P
authors.lastname: Hiltunen
authors.affiliation: Varian Medical Systems, Palo Alto, California, USA.
authors.forename: Reynald
authors.initials: R
authors.lastname: Vanderstraeten
authors.affiliation: Varian Medical Systems, Palo Alto, California, USA.
authors.forename: Jari
authors.initials: J
authors.lastname: Lindberg
authors.affiliation: Varian Medical Systems, Palo Alto, California, USA.
authors.forename: Sami
authors.initials: S
authors.lastname: Siljamaki
authors.affiliation: Varian Medical Systems, Palo Alto, California, USA.
authors.forename: Todd
authors.initials: T
authors.lastname: Wareing
authors.affiliation: Varian Medical Systems, Palo Alto, California, USA.
authors.forename: Ian
authors.initials: I
authors.lastname: Davis
authors.affiliation: Varian Medical Systems, Palo Alto, California, USA.
authors.forename: Allen
authors.initials: A
authors.lastname: Barnett
authors.affiliation: Varian Medical Systems, Palo Alto, California, USA.
authors.forename: John
authors.initials: J
authors.lastname: McGhee
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Charles B
authors.initials: CB
authors.lastname: Simone
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Solberg
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: James E
authors.initials: JE
authors.lastname: McDonough
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Ainsley
mesh_terms: D000465:Algorithms; D019985:Benchmarking; D006801:Humans; D009010:Monte Carlo Method; D009369:Neoplasms / Q000532:radiotherapy*; D019047:Phantoms, Imaging; D061766:Proton Therapy / Q000379:methods*; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods
keywords: AcurosPT; Monte Carlo dose calculation; commissioning; pencil beam scanning; proton therapy