A Monte Carlo feasibility study for neutron based real-time range verification in proton therapy

Ytre-Hauge, Kristian S.; Skjerdal, K.; Mattingly, John; Meriç, Ilker

doi:10.1038/s41598-019-38611-w

Cited by 21 publications

(14 citation statements)

References 29 publications

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“…Therefore, if the difference in the depth dose distribution between PENH and TOPAS were originated on the assumed neutron local deposition done by PENH, both curves should coincide at the Bragg peak depth, where neutron production becomes nearly zero. 52 The origin of this discrepancy can be explained by differences in the modeling of elastic collisions and inelastic collisions, and differences in the transport used in PENH and TOPAS, whose consequences appear magnified by the small bin size employed at the central axis. This is evident from the fact that a few millimeters away from the central beam axis the dose distributions from PENH and TOPAS nearly coincide.…”

Section: Discussionmentioning

confidence: 99%

Single pencil beam benchmark of a module for Monte Carlo simulation of proton transport in the PENELOPE code

et al. 2020

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Background and purpose: PENH is a recently coded module for simulation of proton transport in conjunction with the Monte Carlo code PENELOPE. PENELOPE applies class II simulation to all type of interactions, in particular, to elastic collisions. PENH uses calculated differential cross sections for proton elastic collisions that include electron screening effects as well as nuclear structure effects. Proton-induced nuclear reactions are simulated from information in the ENDF-6 database or from alternative nuclear databases in ENDF format. The purpose of this work is to benchmark this module by simulating absorbed dose distributions from a single finite spot size proton pencil beam in water. Materials and methods: Monte Carlo simulations with PENH are compared with simulation results from TOPAS Monte Carlo (v3.1p2) and RayStation Monte Carlo (v6). Different beam models are examined in terms of mean energy and energy spread to match the measured profiles. The phase-space file is derived from experimental measurements. Simulated absorbed dose distributions are compared to experimental data obtained with the ionization chamber array MatriXX 2D detector (IBA Dosimetry) in a water tank. The experiments were conducted with a clinical IBA pencil beam scanning dedicated nozzle. In all simulations a Fermi-Eyges phase-space representation of a single finite spot size proton pencil beam is used. Results: In general, there is a good agreement between simulated results and experimental data up to a distance of 3 cm from the central axis. In the core region (region where the dose is more than 10% of the maximum dose) PENH shows, overall, the smallest deviations from experimental data, with the largest radial rms (root mean square) smaller than 0.2. The results achieved by TOPAS and RayStation in that region are very close to those of PENH. For the halo region, that is the area of the dose distribution outside the core region reaching down to 0.01% of the maximum intensity, the largest rms achieved by TOPAS is always smaller than 0.5, yielding better results than the rest of the codes. Conclusion: The physics modeling of the PENELOPE/PENH code yields results consistent with measurements in the dose range relevant for proton therapy. The discrepancies between PENH appearing at distances larger than 3 cm from the central-beam axis are accountable to the lack of neutron simulation in this code. In contradistinction, TOPAS has a better agreement with experimental data at large distances from the central-beam axis because of the simulation of neutrons.

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Section: Discussionmentioning

confidence: 99%

Single pencil beam benchmark of a module for Monte Carlo simulation of proton transport in the PENELOPE code

et al. 2020

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“…Prompt gamma (PG) monitoring allows a proper assessment of the distal dose falloff of the proton beam during the treatment 4 . Unlike the produced positron emitters 5 or neutrons 6 , the spatial distribution of the emitted prompt gamma rays shows a very close correlation with the proton dose distribution at the end of the beam 7 . Moreover, these gamma rays are prompt, which means that they are emitted within 1 ns after the collision, which is key for the online verification of the proton range.…”

Section: Introductionmentioning

confidence: 93%

“…For these ancillary simulations, we used the same physics models and distance between the S-and A-planes of i-TED as before. Each MC event (S&A coincidence) contains the same eight features determined with the detector in a real measurement: 3D coordinates of the γ-ray interactions in the two PSDs (6), energy deposited in the S-and A-planes (E s , E a ) (2). The energy and position resolutions of the detector were included as described before.…”

Section: Machine-learning Aided Full-energy Event Selectionmentioning

confidence: 99%

“…This reduces the intrinsic background level and enhances the signal-to-background ratio. Similarly, PGI is also challenged by the background induced by neutrons originating from nuclear reactions of the primary proton beam 4,6,36 . In the case of carbon-ion beams, neutron production is even more pronounced and their discrimination against prompt γ-rays is an issue 4 .…”

Section: Introductionmentioning

confidence: 99%

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Towards machine learning aided real-time range imaging in proton therapy

Lerendegui-Marco¹,

Balibrea-Correa²,

Babiano-Súarez³

et al. 2022

Preprint

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Compton imaging represents a promising technique for range verification in proton therapy treatments. In this work, we report on the advantageous aspects of the i-TED detector for proton-range monitoring, based on the results of the first Monte Carlo study of its applicability to this field. i-TED is an array of Compton cameras, that have been specifically designed for neutron-capture nuclear physics experiments, which are characterized by γ-ray energies spanning up to 5-6 MeV, rather low γ-ray emission yields and very intense neutron induced γ-ray backgrounds. Our developments to cope with these three aspects are concomitant with those required in the field of hadron therapy, especially in terms of high efficiency for real-time monitoring, low sensitivity to neutron backgrounds and reliable performance at the high γ-ray energies. We find that signal-to-background ratios can be appreciably improved with i-TED thanks to its light-weight design and the low neutron-capture cross sections of its LaCl 3 crystals, when compared to other similar systems based on LYSO, CdZnTe or LaBr 3 . Its high time-resolution (CRT∼500 ps) represents an additional advantage for background suppression when operated in pulsed HT mode. Each i-TED Compton module features two detection planes of very large LaCl 3 monolithic crystals, thereby achieving a high efficiency in coincidence of 0.2% for a point-like 1 MeV γ-ray source at 5 cm distance. This leads to sufficient statistics for reliable image reconstruction with an array of four i-TED detectors assuming clinical intensities of 10 8 protons per treatment point. The use of a two-plane design instead of three-planes has been preferred owing to the higher attainable efficiency for double time-coincidences than for threefold events. The loss of full-energy events for high energy γ-rays is compensated by means of Machine-Learning based algorithms, which allow one to enhance the signal-to-total ratio up to a factor of 2.

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“…In this framework, the measurement and calculation of TCS of a vast set of materials are challenging tasks, owing to the several non-trivial dependencies on the molecular structure, dynamics, and thermodynamic temperature. When the TCS calculation is applied to human tissues or muscles for applications such as Boron Neutron Capture Therapy (BNCT) 41,42 as well as to study secondary neutrons-emission induced during proton therapy 43,44 , the possibility to reconstruct the cross section of large proteins becomes challenging. In fact, the 20 basic amino acids can combine to form tens of thousands 45 up to several billions of proteins 46 , making the task of either calculate or measure the entire set of related TCS unrealistic.…”

Section: Introductionmentioning

confidence: 99%

Thermal neutron cross sections of amino acids from average contributions of functional groups

Romanelli,

Onorati,

Ulpiani

et al. 2021

Preprint

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The experimental thermal neutron cross sections of the twenty proteinogenic amino acids have been measured over the incident-neutron energy range spanning from 1 meV to 10 keV and data have been interpreted using the multi-phonon expansion based on first-principles calculations. The scattering cross section, dominated by the incoherent inelastic contribution from the hydrogen atoms, can be rationalised in terms of the average contributions of different functional groups, thus neglecting their correlation. These results can be used for modelling the total neutron cross sections of complex organic systems like proteins, muscles, or human tissues from a limited number of starting input functions. This simplification is of crucial importance for fine-tuning of transport simulations used in medical applications, including boron neutron capture therapy as well as secondary neutrons-emission induced during proton therapy. Moreover, the parametrized neutron cross sections allow a better treatment of neutron scattering experiments, providing detailed sample self-attenuation corrections for a variety of biological and soft-matter systems.

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A Monte Carlo feasibility study for neutron based real-time range verification in proton therapy

Cited by 21 publications

References 29 publications

Single pencil beam benchmark of a module for Monte Carlo simulation of proton transport in the PENELOPE code

Single pencil beam benchmark of a module for Monte Carlo simulation of proton transport in the PENELOPE code

Towards machine learning aided real-time range imaging in proton therapy

Thermal neutron cross sections of amino acids from average contributions of functional groups

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