Dosimetry and radioprotection evaluations of very high energy electron beams

AbstractVery high energy electrons (VHEEs) represent a promising alternative for the treatment of deep-seated tumors over conventional radiotherapy (RT), owing to their favourable dosimetric characteristics. Given the high energy of the electrons, one of the concerns has been the production of photoneutrons. In this article we explore the consequence, in terms of neutron yield in a water phantom, of using a typical electron applicator in conjunction with a 2 GeV and 200 MeV VHEE beam. Additionally, we evaluate the resulting ambient neutron dose equivalent at various locations between the phantom and a concrete wall. Through Monte Carlo (MC) simulations it was found that an applicator acts to reduce the depth of the dose build-up region, giving rise to lower exit doses but higher entrance doses. Furthermore, neutrons are injected into the entrance region of the phantom. The highest dose equivalent found was approximately 1.7 mSv/Gy in the vicinity of the concrete wall. Nevertheless, we concluded that configurations of VHEEs studied in this article are similar to conventional proton therapy treatments in terms of their neutron yield and ambient dose equivalent. Therefore, a clinical implementation of VHEEs would likely not warrant additional radioprotection safeguards compared to conventional RT treatments.

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First theoretical determination of relative biological effectiveness of very high energy electrons

Scientific Reports ◽

10.1038/s41598-021-90805-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Rachel Delorme ◽

Thongchai A. M. Masilela ◽

Camille Etoh ◽

François Smekens ◽

Yolanda Prezado

Keyword(s):

Electron Beams ◽

Rapid Development ◽

High Energy ◽

High Dose ◽

Clinical Implementation ◽

Biological Efficacy ◽

Lineal Energy ◽

High Energy Electrons ◽

Very High Energy ◽

Very High

AbstractVery high energy electrons (VHEEs, E > 70 MeV) present promising clinical advantages over conventional beams due to their increased range, improved penumbra and relative insensitivity to tissue heterogeneities. They have recently garnered additional interest in their application to spatially fractionated radiotherapy or ultra-high dose rate (FLASH) therapy. However, the lack of radiobiological data limits their rapid development. This study aims to provide numerical biologically-relevant information by characterizing VHEE beams (100 and 300 MeV) against better-known beams (clinical energy electrons, photons, protons, carbon and neon ions). Their macro- and microdosimetric properties were compared, using the dose-averaged linear energy transfer ($$\overline{{L_{d} }}$$ L d ¯ ) as the macroscopic metric, and the dose-mean lineal energy $$\overline{{y_{d} }}$$ y d ¯ and the dose-weighted lineal energy distribution, yd(y), as microscopic metrics. Finally, the modified microdosimetric kinetic model was used to calculate the respective cell survival curves and the theoretical RBE. From the macrodosimetric point of view, VHEEs presented a potential improved biological efficacy over clinical photon/electron beams due to their increased $$\overline{{L_{d} }}$$ L d ¯ . The microdosimetric data, however, suggests no increased biological efficacy of VHEEs over clinical electron beams, resulting in RBE values of approximately 1, giving confidence to their clinical implementation. This study represents a first step to complement further radiobiological experiments.

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Neutrons along the labyrinth of high energy medical accelerators: Effect of wall materials

HNPS Proceedings ◽

10.12681/hnps.2026 ◽

2019 ◽

Vol 21 ◽

pp. 169

Author(s):

M. Fakinou ◽

I. E. Stamatelatos ◽

J. Kalef-Ezra

Keyword(s):

Monte Carlo ◽

Cost Effective ◽

High Energy ◽

Wall Material ◽

Mcnp Code ◽

Dose Equivalent ◽

Concrete Wall ◽

Ambient Dose Equivalent ◽

Wall Materials ◽

Ambient Dose

Neutron streaming along the labyrinth of a generic bunker of an 18MV medical accelerator was evaluated. Monte Carlo simulations using MCNP code were performed to calculate neutron ambient dose equivalent along the labyrinth. The effect of plain, borated and barites concrete wall material, as well as borated concrete and plywood (Celotex), as neutron absorbing wall liners, was examined. The results of the study suggest that plywood can provide a cost effective material to attenuate neutron streaming along the labyrinth.

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Back to the Future: Very High-Energy Electrons (VHEEs) and Their Potential Application in Radiation Therapy

Cancers ◽

10.3390/cancers13194942 ◽

2021 ◽

Vol 13 (19) ◽

pp. 4942

Author(s):

Maria Grazia Ronga ◽

Marco Cavallone ◽

Annalisa Patriarca ◽

Amelia Maia Leite ◽

Pierre Loap ◽

...

Keyword(s):

Radiation Therapy ◽

Current Knowledge ◽

High Energy ◽

High Dose Rate ◽

Point Of View ◽

High Dose ◽

Dose Rates ◽

High Energy Electrons ◽

Very High Energy ◽

Very High

The development of innovative approaches that would reduce the sensitivity of healthy tissues to irradiation while maintaining the efficacy of the treatment on the tumor is of crucial importance for the progress of the efficacy of radiotherapy. Recent methodological developments and innovations, such as scanned beams, ultra-high dose rates, and very high-energy electrons, which may be simultaneously available on new accelerators, would allow for possible radiobiological advantages of very short pulses of ultra-high dose rate (FLASH) therapy for radiation therapy to be considered. In particular, very high-energy electron (VHEE) radiotherapy, in the energy range of 100 to 250 MeV, first proposed in the 2000s, would be particularly interesting both from a ballistic and biological point of view for the establishment of this new type of irradiation technique. In this review, we examine and summarize the current knowledge on VHEE radiotherapy and provide a synthesis of the studies that have been published on various experimental and simulation works. We will also consider the potential for VHEE therapy to be translated into clinical contexts.

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Toward an effective use of laser-driven very high energy electrons for radiotherapy: Feasibility assessment of multi-field and intensity modulation irradiation schemes

Scientific Reports ◽

10.1038/s41598-020-74256-w ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Luca Labate ◽

Daniele Palla ◽

Daniele Panetta ◽

Federico Avella ◽

Federica Baffigi ◽

...

Keyword(s):

High Energy ◽

High Dose Rate ◽

High Dose ◽

Feasibility Assessment ◽

High Energy Electrons ◽

Very High Energy ◽

Effective Use ◽

Dose Deposition ◽

Therapeutic Doses ◽

Very High

Abstract Radiotherapy with very high energy electrons has been investigated for a couple of decades as an effective approach to improve dose distribution compared to conventional photon-based radiotherapy, with the recent intriguing potential of high dose-rate irradiation. Its practical application to treatment has been hindered by the lack of hospital-scale accelerators. High-gradient laser-plasma accelerators (LPA) have been proposed as a possible platform, but no experiments so far have explored the feasibility of a clinical use of this concept. We show the results of an experimental study aimed at assessing dose deposition for deep seated tumours using advanced irradiation schemes with an existing LPA source. Measurements show control of localized dose deposition and modulation, suitable to target a volume at depths in the range from 5 to 10 cm with mm resolution. The dose delivered to the target was up to 1.6 Gy, delivered with few hundreds of shots, limited by secondary components of the LPA accelerator. Measurements suggest that therapeutic doses within localized volumes can already be obtained with existing LPA technology, calling for dedicated pre-clinical studies.

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