Monte Carlo simulation of the photoneutron field in linac radiotherapy treatments with different collimation systems

Zanini, A.; Durisi, Elisabetta Alessandra; Fasolo, F.; Ongaro, C.; Visca, L.; Nastasi, U.; Burn, KW; Scielzo, G; Adler, J.-O.; Annand, J. R. M.; Rosner, G.

doi:10.1088/0031-9155/49/4/008

Cited by 89 publications

(62 citation statements)

References 6 publications

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“…Our data are consistent with those reported recently by Zanini et al 12 In their study, Zanini et al Table III, which shows the measured neutron fluence per MU, the average energy of the measured spectrum, and the ambient dose equivalent ͑H ‫ء‬ ͑10͒͒ for each configuration.…”

Section: Discussionsupporting

confidence: 93%

Effects of tertiary MLC configuration on secondary neutron spectra from 18 MV x‐ray beams for the Varian 21EX linear accelerator

et al. 2009

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The effect of the jaw configuration and the presence and configuration of the tertiary multileaf collimator ͑MLC͒ on the secondary neutron spectra for an 18 MV Varian 21EX linear accelerator ͑linac͒ is investigated in detail. The authors report the measured spectra for four collimator ͑jaw-and-MLC͒ configurations. These configurations represent the extreme settings of the jaws and MLC and should therefore describe the range of possible fluence and spectra that may be encountered during use of this linac. In addition to measurements, a Monte Carlo model was used to simulate the four collimator configurations and calculate the energy spectra and fluence at the same location as it was measured. The Monte Carlo model was also used to calculate the sources of neutron production in the linac head for each collimator configuration. They found that photoneutron production in the linac treatment head is dominated by the order in which the primary photon beam intercepts the high-Z material. The primary collimator, which has the highest position in the linac head ͑in a fixed location͒, is the largest source of secondary neutrons. Thereafter, the collimator configuration plays a role in where the neutrons originate. For instance, if the jaws are closed, they intercept the beam and contribute substantially to the secondary neutron production. Conversely, if the jaws are open, the MLC plays a larger role in neutron production ͑assuming, of course, that it intercepts the beam͒. They found that different collimator configurations make up to a factor of 2 difference in the ambient dose equivalent.

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Section: Discussionsupporting

confidence: 93%

Effects of tertiary MLC configuration on secondary neutron spectra from 18 MV x‐ray beams for the Varian 21EX linear accelerator

et al. 2009

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“…The employed photo-reaction model assumes that the dominant neutron emission mechanism is evaporation, with a maxwellian neutron energy distribution and an isotropic angular distribution. A small direct neutron emission component, with resulting En>2 MeV, is also considered (Ongaro et al 1999;Zanini et al, 2004). To check the model validity a comparison with MCNP5, which uses different cross sections libraries, has been done.…”

Section: Monte Carlo Simulationsmentioning

confidence: 99%

Design and simulation of an optimized e-linac based neutron source for BNCT research

Durisi

Alikaniotis

Borla

et al. 2015

Applied Radiation and Isotopes

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The paper is focused on the study of a novel photo-neutron source for BNCT preclinical research based on medical electron Linacs. Previous studies by the authors already demonstrated the possibility to obtain a mixed thermal and epithermal neutron flux of the order of 10 7 cm -2 s -1 . This paper investigates possible Linac's modifications and a new photo-converter design to rise the neutron flux above 5 10 7 cm -2 s -1 , also reducing the gamma contamination.

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“…As the nucleons are bounded with the nucleus by binding energy (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) MeV), the photon should have energy above a threshold value to participate in the photonuclear reaction. Neutrons from the photoninduced giant-dipole-resonance (GDR) reaction consist of a large portion of evaporation neutrons which dominate at low neutron energies (< 1-2 MeV), and a small fraction of direct neutrons, which dominate at high energies [6].…”

Section: Introductionmentioning

confidence: 99%

Characteristics of a heavy water photoneutron source in boron neutron capture therapy

2013

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Abstract:Bremsstrahlung photon beams produced by medical linear accelerators are currently the most commonly used method of radiation therapy for cancerous tumors. Photons with energies greater than 8-10 MeV potentially generate neutrons through photonuclear interactions in the accelerator's treatment head, patient's body, and treatment room ambient. Electrons impinging on a heavy target generate a cascade shower of bremsstrahlung photons which energy spectrum shows an end point equal to the electron beam energy. By varying the target thickness, an optimum thickness exists for which, at the given electron energy, maximum photon flux is achievable. If a source of high-energy photons i.e. bremsstrahlung, is conveniently directed to a suitable D2O target, a novel approach for production of an acceptable flux of filterable photoneturons for boron neutron capture therapy (BNCT) application is possible. This study consists of two parts: 1. Comparison and assessment of deuterium photonuclear cross section data. 2. Evaluation of heavy water photonuclear source.

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Monte Carlo simulation of the photoneutron field in linac radiotherapy treatments with different collimation systems

Cited by 89 publications

References 6 publications

Effects of tertiary MLC configuration on secondary neutron spectra from 18 MV x‐ray beams for the Varian 21EX linear accelerator

Effects of tertiary MLC configuration on secondary neutron spectra from 18 MV x‐ray beams for the Varian 21EX linear accelerator

Design and simulation of an optimized e-linac based neutron source for BNCT research

Characteristics of a heavy water photoneutron source in boron neutron capture therapy

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