A Fano cavity test for Monte Carlo proton transport algorithms

Sterpin, Edmond; Sorriaux, Jefferson; Souris, Kevin; Vynckier, Stefaan; Bouchard, Hugo

doi:10.1118/1.4835475

Cited by 22 publications

(28 citation statements)

References 31 publications

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“…The choice of MC simulations parameters is important to get realistic dose deposition in small air cavities. Results of previous work on the Fano test drove the choice of setCutInRegion, dRoverRange, and finalRange parameters for protons. The setCutInRegion parameter is sensitive to get accurate stopping power ratios at z ref , especially for protons and electrons.…”

Section: Resultsmentioning

confidence: 99%

“…MC simulations are widely used to compute ionization chamber response in radiation beams. Sterpin et al showed that Geant4 is reliable for ionization chamber proton dose calculation using appropriate settings. Quality correction factors could be measured or obtained from MC simulations as follow:

{normalk}_{{normalQ}_{normalA}, {normalQ}_{normalB}} = \frac{{(\frac{{normalD}_{normalw}}{{\overset{D}{true}}_{a i r}})}_{{normalQ}_{normalA}}}{{(\frac{{normalD}_{normalw}}{{\overset{D}{true}}_{a i r}})}_{{normalQ}_{normalB}}} \frac{{(\frac{{normalW}_{normalair}}{e})}_{{normalQ}_{normalA}}}{{(\frac{{normalW}_{normalair}}{e})}_{{normalQ}_{normalB}}}

If Q A and Q B are proton beams, the mean energy to create an ion pair in air, W air /e can be simplified and

{normalk}_{{normalQ}_{normalA}, {normalQ}_{normalB}} = \frac{{(\frac{{normalD}_{normalw}}{{\overset{D}{true}}_{a i r}})}_{{normalQ}_{normalA}}}{{(\frac{{normalD}_{normalw}}{{\overset{D}{true}}_{a i r}})}_{{normalQ}_{normalB}}}

…”

Section: Methodsmentioning

confidence: 99%

“…Note that Table parameters are more strict than Geant4 emstandard_opt3 usually defined for applications requiring higher accuracy of electrons, hadrons, and ion transport without magnetic field . More conservative values for protons setCutInRegion and finalRange parameters are chosen from previous work on the Fano test that has evaluated Geant4 proton transport in a small cavity of low‐density material. Concerning Geant4 electron transport, Elles et al reported improvements and performances of multiple‐scattering algorithm on the Fano test for electrons.…”

Section: Methodsmentioning

confidence: 99%

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Consistency in quality correction factors for ionization chamber dosimetry in scanned proton beam therapy

et al. 2017

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The Alfonso formalism was applied to scanned proton beams. In our MC simulations, neither the difference in the beam profiles (scanned beam vs hypothetical beam) nor the different incident beam energies influenced significantly the beam correction factors. This suggests that ionization chamber quality correction factors in scanned or broad proton beams are indistinguishable within the calculation uncertainties provided dose distributions achieved by both modalities are similar and compliant with the TRS-398 reference conditions.

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Section: Resultsmentioning

confidence: 99%

{normalk}_{{normalQ}_{normalA}, {normalQ}_{normalB}} = \frac{{(\frac{{normalD}_{normalw}}{{\overset{D}{true}}_{a i r}})}_{{normalQ}_{normalA}}}{{(\frac{{normalD}_{normalw}}{{\overset{D}{true}}_{a i r}})}_{{normalQ}_{normalB}}} \frac{{(\frac{{normalW}_{normalair}}{e})}_{{normalQ}_{normalA}}}{{(\frac{{normalW}_{normalair}}{e})}_{{normalQ}_{normalB}}}

If Q A and Q B are proton beams, the mean energy to create an ion pair in air, W air /e can be simplified and

{normalk}_{{normalQ}_{normalA}, {normalQ}_{normalB}} = \frac{{(\frac{{normalD}_{normalw}}{{\overset{D}{true}}_{a i r}})}_{{normalQ}_{normalA}}}{{(\frac{{normalD}_{normalw}}{{\overset{D}{true}}_{a i r}})}_{{normalQ}_{normalB}}}

…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Consistency in quality correction factors for ionization chamber dosimetry in scanned proton beam therapy

et al. 2017

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“…The accuracy of electron transport algorithms has been validated in several MC codes, such as EGSnrc, PENELOPE Geant4 . Sterpin et al, have designed a Fano cavity test for proton transport using Geant4 and PENH (PENELOPE extended to protons). Both codes were found to pass the Fano cavity test within 0.1% by using small step sizes.…”

Section: Introductionmentioning

confidence: 99%

The influence of nuclear interactions on ionization chamber perturbation factors in proton beams: FLUKA simulations supported by a Fano test

et al. 2018

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Purpose In all recent protocols for the reference dosimetry of clinical proton beams, ionization chamber perturbation factors are assumed to be unity. In this work, such factors were computed using the FLUKA Monte Carlo code for three ionization chamber types, with particular attention to the influence of nuclear interactions. Methods The accuracy of the transport algorithms implemented in FLUKA was first evaluated by performing a Fano cavity test. Ionization chamber perturbation factors were computed for the PTW‐34001 Roos® and the PTW‐34070 and PTW‐34073 Bragg peak® chambers for proton beams of 60–250 MeV using the same transport parameters that were needed to pass the Fano test. Results FLUKA was found to pass the Fano test within 0.15%. Ionization chamber simulation results show that the presence of the air cavity and the wall results in dose perturbations of the order of 0.6% and 0.8%, respectively. The perturbation factors are shown to be energy dependent and nuclear interactions must be taken into account for accurate calculation of the ionization chamber's response. Conclusion Ionization chamber perturbations can amount to 1% in high‐energy proton beams and therefore need to be considered in dosimetry procedures.

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“…penh is an extension of the Monte Carlo code penelope that includes the transport of protons based on their electromagnetic interactions in matter. Proton nuclear interactions and prompt‐gamma emission are included for a limited number of isotopes:

^{1}

^{12}

^{14}

^{16}

^{31}

^{40}

Ca.

^{30}

Both penelope and penh have been reported to pass the Fano test within 0.1% for the energy range of interest to this work. Furthermore, penh has been shown to yield

k_{Q}

factors in proton beams in good agreement with experimental data .…”

Section: Methodsmentioning

confidence: 99%

Comparison of penh, fluka, and Geant4/topas for absorbed dose calculations in air cavities representing ionization chambers in high‐energy photon and proton beams

et al. 2019

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Purpose The purpose of this work is to analyze whether the Monte Carlo codes penh, fluka, and geant4/topas are suitable to calculate absorbed doses and fQ/fQ0 ratios in therapeutic high‐energy photon and proton beams. Methods We used penh, fluka, geant4/topas, and egsnrc to calculate the absorbed dose to water in a reference water cavity and the absorbed dose to air in two air cavities representative of a plane‐parallel and a cylindrical ionization chamber in a 1.25 MeV photon beam and a 150 MeV proton beam — egsnrc was only used for the photon beam calculations. The physics and transport settings in each code were adjusted to simulate the particle transport as detailed as reasonably possible. From these absorbed doses, fQ0 factors, fQ factors, and fQ/fQ0 ratios (which are the basis of Monte Carlo calculated beam quality correction factors kQ,Q0) were calculated and compared between the codes. Additionally, we calculated the spectra of primary particles and secondary electrons in the reference water cavity, as well as the integrated depth–dose curve of 150 MeV protons in water. Results The absorbed doses agreed within 1.4% or better between the individual codes for both the photon and proton simulations. The fQ0 and fQ factors agreed within 0.5% or better for the individual codes for both beam qualities. The resulting fQ/fQ0 ratios for 150 MeV protons agreed within 0.7% or better. For the 1.25 MeV photon beam, the spectra of photons and secondary electrons agreed almost perfectly. For the 150 MeV proton simulation, we observed differences in the spectra of secondary protons whereas the spectra of primary protons and low‐energy delta electrons also agreed almost perfectly. The first 2 mm of the entrance channel of the 150 MeV proton Bragg curve agreed almost perfectly while for greater depths, the differences in the integrated dose were up to 1.5%. Conclusion penh, fluka, and geant4/topas are capable of calculating beam quality correction factors in proton beams. The differences in the fQ0 and fQ factors between the codes are 0.5% at maximum. The differences in the fQ/fQ0 ratios are 0.7% at maximum.

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A Fano cavity test for Monte Carlo proton transport algorithms

Abstract: Using conservative user-defined simulation parameters, both PENH and Geant4 pass the Fano cavity test for proton transport. Our methodology is applicable to any kind of charged particle, provided that the considered MC code is able to track the charged particle considered.

Cited by 22 publications

References 31 publications

Consistency in quality correction factors for ionization chamber dosimetry in scanned proton beam therapy

Consistency in quality correction factors for ionization chamber dosimetry in scanned proton beam therapy

The influence of nuclear interactions on ionization chamber perturbation factors in proton beams: FLUKA simulations supported by a Fano test

Comparison of penh, fluka, and Geant4/topas for absorbed dose calculations in air cavities representing ionization chambers in high‐energy photon and proton beams

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