The impact of treatment parameter variation on secondary neutron spectra in high-energy electron beam radiotherapy

Mathew, Felix; Makdessi, G. Al; Montgomery, Logan; Evans, Michael D.; Kildea, J.

doi:10.1016/j.ejmp.2020.10.016

Cited by 8 publications

(3 citation statements)

References 46 publications

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“…The electroneutron production is foreseen to principally occur in the scattering foil, which is usually made of tungsten or tantalum and thick of a few tens of µm. In recent years, an increasing interest can be reported towards electroneutron production from medical accelerators [69][70][71][72][73]. In 2012, H.R.…”

Section: 2)mentioning

confidence: 99%

Characterization of photoneutron fluxes emitted by electron accelerators in the 4–20 MeV range using Monte Carlo codes: A critical review

Sari

2023

Applied Radiation and Isotopes

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Section: 2)mentioning

confidence: 99%

Characterization of photoneutron fluxes emitted by electron accelerators in the 4–20 MeV range using Monte Carlo codes: A critical review

Sari

2023

Applied Radiation and Isotopes

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“…The generation of secondary neutrons by electron beams involves a two-step process (NCRP 1984). Initially, an electron undergoes inelastic scattering by the Coulomb field of an atomic nucleus, resulting in the creation of a bremsstrahlung photon (Attix 2008, Khan and Gibbons 2014, Mathew et al 2020. Subsequently, this photon interacts with atomic nucleus through the photodisintegration reaction, leading to the ejection of a neutron from the nucleus (Attix 2008, Khan and Gibbons 2014, Mathew et al 2020.…”

Section: Introduction and Goalsmentioning

confidence: 99%

Thermal neutron detection and track recognition method in reference and out-of-field radiotherapy FLASH electron fields using Timepix3 detectors

Oancea,

Solc,

Bourgouin

et al. 2023

Phys. Med. Biol.

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Objective. This work presents a method for enhanced detection, imaging, and measurement of the thermal neutron flux. Approach. Measurements were performed in a water tank, while the detector is positioned out-of-field of a 20 MeV ultra-high pulse dose rate electron beam. A semiconductor pixel detector Timepix3 with a silicon sensor partially covered by a 6LiF neutron converter was used to measure the flux, spatial, and time characteristics of the neutron field. To provide absolute measurements of thermal neutron flux, the detection efficiency calibration of the detectors was performed in a reference thermal neutron field. Neutron signals are recognized and discriminated against other particles such as gamma rays and x-rays. This is achieved by the resolving power of the pixel detector using machine learning algorithms and high-resolution pattern recognition analysis of the high-energy tracks created by thermal neutron interactions in the converter. Main results. The resulting thermal neutrons equivalent dose was obtained using conversion factor (2.13(10) pSv·cm2) from thermal neutron fluence to thermal neutron equivalent dose obtained by Monte Carlo simulations. The calibrated detectors were used to characterize scattered radiation created by electron beams. The results at 12.0 cm depth in the beam axis inside of the water for a delivered dose per pulse of 1.85 Gy (pulse length of 2.4 μs) at the reference depth, showed a contribution of flux of 4.07(8) × 103 particles·cm−2·s−1 and equivalent dose of 1.73(3) nSv per pulse, which is lower by ∼9 orders of magnitude than the delivered dose. Significance. The presented methodology for in-water measurements and identification of characteristic thermal neutrons tracks serves for the selective quantification of equivalent dose made by thermal neutrons in out-of-field particle therapy.

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“…In previous studies, the measurement of photoneutrons was more often carried out free-in-air at various locations in the patient plane [9,[11][12][13] or in the water phantom [11,14]. Various types of equipment can be used for measurement, including a Bonner sphere spectrometer [15], a nested neutron spectrometer (NNS, Detec Inc., Gatineau, QC, Canada) [16], a Meridian Neutron Survey Meter 5085 (HPI, Goleta, CA, USA) [12], and CR-39 detectors [14]. Photoneutron dosimetry is a challenge because the measurement is carried out in a mixed field with photons, which can lead to an uncertainty of about 10% due to the saturation of the detector and the strong dependence of the detector response on the neutron spectrum [17].…”

Section: Introductionmentioning

confidence: 99%

GEANT4 Simulation of Photoneutron Spectrum from Medical Linear Accelerator

Chernyaev,

Belikhin,

Lykova

et al. 2023

QuBS

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Photons with energy totaling more than 10 MeV provide efficient treatment for deeply seated tumors but interact with the nuclei of high-Z materials constituting a head of the linac. These interactions result in photoneutrons that deliver an additional out-of-field dose to the patient, which increases the risk of radiation-induced cancer. Monte Carlo simulation is an accurate strategy for estimating the effective photoneutron dose for a patient. In the current study, the possibility of using GEANT4 to calculate the photoneutron spectrum from the medical linac was investigated. The free-in-air photoneutron spectrum from a head of the linac was simulated using the NeutronHP experimental package. Validation of the simulated model was carried out based on a comparison of simulated and measured percentage depth–dose curves from photons in the water phantom. The obtained photoneutron spectrum was compared with the previously measured spectrum at the Varian Thilogy linac. GEANT4 may improve the accuracy of calculations of the effective dose based on photoneutrons. However, the simulated model should be improved and optimized. In the future, this model may constitute a physical basis for the prediction of the risk of radiation-induced cancer at our clinical center.

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The impact of treatment parameter variation on secondary neutron spectra in high-energy electron beam radiotherapy

Cited by 8 publications

References 46 publications

Characterization of photoneutron fluxes emitted by electron accelerators in the 4–20 MeV range using Monte Carlo codes: A critical review

Characterization of photoneutron fluxes emitted by electron accelerators in the 4–20 MeV range using Monte Carlo codes: A critical review

Thermal neutron detection and track recognition method in reference and out-of-field radiotherapy FLASH electron fields using Timepix3 detectors

GEANT4 Simulation of Photoneutron Spectrum from Medical Linear Accelerator

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