An MCNPX Monte Carlo Model of a Discrete Spot Scanning Proton Beam Therapy Nozzle

Overview

Journal Med Phys

Specialty Biophysics

Date 2010 Oct 23

PMID 20964215

Citations 22

Authors

Gabriel O Sawakuchi

Dragan Mirkovic

Luis A Perles

Narayan Sahoo

X Ron Zhu

George Ciangaru

Kazumichi Suzuki

Michael T Gillin

Radhe Mohan

Uwe Titt

Affiliations

Soon will be listed here.

Abstract

Purpose: The purposes of this study were to validate a discrete spot scanning proton beam nozzle using the Monte Carlo (MC) code MCNPX and use the MC validated model to investigate the effects of a low-dose envelope, which surrounds the beam's central axis, on measurements of integral depth dose (IDD) profiles.

Methods: An accurate model of the discrete spot scanning beam nozzle from The University of Texas M. D. Anderson Cancer Center (Houston, Texas) was developed on the basis of blueprints provided by the manufacturer of the nozzle. The authors performed simulations of single proton pencil beams of various energies using the standard multiple Coulomb scattering (MCS) algorithm within the MCNPX source code and a new MCS algorithm, which was implemented in the MCNPX source code. The MC models were validated by comparing calculated in-air and in-water lateral profiles and percentage depth dose profiles for single pencil beams with their corresponding measured values. The models were then further tested by comparing the calculated and measured three-dimensional (3-D) dose distributions. Finally, an IDD profile was calculated with different scoring radii to determine the limitations on the use of commercially available plane-parallel ionization chambers to measure IDD.

Results: The distance to agreement, defined as the distance between the nearest positions of two equivalent distributions with the same value of dose, between measured and simulated ranges was within 0.13 cm for both MCS algorithms. For low and intermediate pencil beam energies, the MC simulations using the standard MCS algorithm were in better agreement with measurements. Conversely, the new MCS algorithm produced better results for high-energy single pencil beams. The IDD profile calculated with cylindrical tallies with an area equivalent to the area of the largest commercially available ionization chamber showed up to 7.8% underestimation of the integral dose in certain depths of the IDD profile.

Conclusions: The authors conclude that a combination of MCS algorithms is required to accurately reproduce experimental data of single pencil beams and 3-D dose distributions for the scanning beam nozzle. In addition, the MC simulations showed that because of the low-dose envelope, ionization chambers with radii as large as 4.08 cm are insufficient to accurately measure IDD profiles for a 221.8 MeV pencil beam in the scanning beam nozzle.

Citing Articles

Experimental and Monte Carlo characterization of a dynamic collimation system prototype for pencil beam scanning proton therapy.

Smith B, Pankuch M, Hyer D, Culberson W Med Phys. 2021; 47(10):5343-5356.

PMID: 33411329 PMC: 8012152. DOI: 10.1002/mp.14453.

Automated Monte-Carlo re-calculation of proton therapy plans using Geant4/Gate: implementation and comparison to plan-specific quality assurance measurements.

Aitkenhead A, Sitch P, Richardson J, Winterhalter C, Patel I, Mackay R Br J Radiol. 2020; 93(1114):20200228.

PMID: 32726141 PMC: 7548378. DOI: 10.1259/bjr.20200228.

Ionization quenching correction for a 3D scintillator detector exposed to scanning proton beams.

Alsanea F, Darne C, Robertson D, Beddar S Phys Med Biol. 2020; 65(7):075005.

PMID: 32079001 PMC: 7682349. DOI: 10.1088/1361-6560/ab7876.

A DNA damage multiscale model for NTCP in proton and hadron therapy.

Abolfath R, Peeler C, Mirkovic D, Mohan R, Grosshans D Med Phys. 2020; 47(4):2005-2012.

PMID: 31955444 PMC: 10015418. DOI: 10.1002/mp.14034.

Validation and clinical implementation of an accurate Monte Carlo code for pencil beam scanning proton therapy.

Huang S, Kang M, Souris K, Ainsley C, Solberg T, McDonough J J Appl Clin Med Phys. 2018; 19(5):558-572.

PMID: 30058170 PMC: 6123159. DOI: 10.1002/acm2.12420.

References

Titt U, Sahoo N, Ding X, Zheng Y, Newhauser W, Zhu X . Assessment of the accuracy of an MCNPX-based Monte Carlo simulation model for predicting three-dimensional absorbed dose distributions. Phys Med Biol. 2008; 53(16):4455-70. PMC: 4131262. DOI: 10.1088/0031-9155/53/16/016. View

Soukup M, Fippel M, Alber M . A pencil beam algorithm for intensity modulated proton therapy derived from Monte Carlo simulations. Phys Med Biol. 2005; 50(21):5089-104. DOI: 10.1088/0031-9155/50/21/010. View

Herault J, Iborra N, Serrano B, Chauvel P . Monte Carlo simulation of a protontherapy platform devoted to ocular melanoma. Med Phys. 2005; 32(4):910-9. DOI: 10.1118/1.1871392. View

Zheng Y, Fontenot J, Taddei P, Mirkovic D, Newhauser W . Monte Carlo simulations of neutron spectral fluence, radiation weighting factor and ambient dose equivalent for a passively scattered proton therapy unit. Phys Med Biol. 2008; 53(1):187-201. DOI: 10.1088/0031-9155/53/1/013. View

Gottschalk B . On the scattering power of radiotherapy protons. Med Phys. 2010; 37(1):352-67. DOI: 10.1118/1.3264177. View

Polf J, Newhauser W . Calculations of neutron dose equivalent exposures from range-modulated proton therapy beams. Phys Med Biol. 2005; 50(16):3859-73. DOI: 10.1088/0031-9155/50/16/014. View

Paganetti H . Monte Carlo calculations for absolute dosimetry to determine machine outputs for proton therapy fields. Phys Med Biol. 2006; 51(11):2801-12. PMC: 2292643. DOI: 10.1088/0031-9155/51/11/008. View

Gottschalk B . Neutron dose in scattered and scanned proton beams: in regard to Eric J. Hall (Int J Radiat Oncol Biol Phys 2006;65:1-7). Int J Radiat Oncol Biol Phys. 2006; 66(5):1594. DOI: 10.1016/j.ijrobp.2006.08.014. View

Sawakuchi G, Zhu X, Poenisch F, Suzuki K, Ciangaru G, Titt U . Experimental characterization of the low-dose envelope of spot scanning proton beams. Phys Med Biol. 2010; 55(12):3467-78. DOI: 10.1088/0031-9155/55/12/013. View

10.

Titt U, Zheng Y, Vassiliev O, Newhauser W . Monte Carlo investigation of collimator scatter of proton-therapy beams produced using the passive scattering method. Phys Med Biol. 2008; 53(2):487-504. DOI: 10.1088/0031-9155/53/2/014. View

11.

Gillin M, Sahoo N, Bues M, Ciangaru G, Sawakuchi G, Poenisch F . Commissioning of the discrete spot scanning proton beam delivery system at the University of Texas M.D. Anderson Cancer Center, Proton Therapy Center, Houston. Med Phys. 2010; 37(1):154-63. PMC: 11078095. DOI: 10.1118/1.3259742. View

12.

Paganetti H, Jiang H, Parodi K, Slopsema R, Engelsman M . Clinical implementation of full Monte Carlo dose calculation in proton beam therapy. Phys Med Biol. 2008; 53(17):4825-53. DOI: 10.1088/0031-9155/53/17/023. View

13.

Zheng Y, Newhauser W, Fontenot J, Taddei P, Mohan R . Monte Carlo study of neutron dose equivalent during passive scattering proton therapy. Phys Med Biol. 2007; 52(15):4481-96. DOI: 10.1088/0031-9155/52/15/008. View

14.

Pedroni E, Scheib S, Bohringer T, Coray A, Grossmann M, Lin S . Experimental characterization and physical modelling of the dose distribution of scanned proton pencil beams. Phys Med Biol. 2005; 50(3):541-61. DOI: 10.1088/0031-9155/50/3/011. View

15.

Newhauser W, Fontenot J, Zheng Y, Polf J, Titt U, Koch N . Monte Carlo simulations for configuring and testing an analytical proton dose-calculation algorithm. Phys Med Biol. 2007; 52(15):4569-84. DOI: 10.1088/0031-9155/52/15/014. View

16.

Sawakuchi G, Titt U, Mirkovic D, Ciangaru G, Zhu X, Sahoo N . Monte Carlo investigation of the low-dose envelope from scanned proton pencil beams. Phys Med Biol. 2010; 55(3):711-21. DOI: 10.1088/0031-9155/55/3/011. View

17.

Deasy J . A proton dose calculation algorithm for conformal therapy simulations based on Molière's theory of lateral deflections. Med Phys. 1998; 25(4):476-83. DOI: 10.1118/1.598222. View

18.

Paganetti H . Monte Carlo method to study the proton fluence for treatment planning. Med Phys. 1999; 25(12):2370-5. DOI: 10.1118/1.598447. View

19.

Polf J, Newhauser W, Titt U . Patient neutron dose equivalent exposures outside of the proton therapy treatment field. Radiat Prot Dosimetry. 2005; 115(1-4):154-8. DOI: 10.1093/rpd/nci264. View

20.

Pedroni E, Bacher R, Blattmann H, Bohringer T, Coray A, Lomax A . The 200-MeV proton therapy project at the Paul Scherrer Institute: conceptual design and practical realization. Med Phys. 1995; 22(1):37-53. DOI: 10.1118/1.597522. View