Description

Electron beams delivered by a linear accelerator (LINAC) make it possible to achieve very high photon energies, on the order of several MeV, with high dose rates, while also enabling the use of multiple beams at different energies using a single accelerator. Such beams are commonly employed in the fields of radiotherapy, the nuclear industry, and the calibration of measurement devices. However, the metrological use of these accelerators requires precise knowledge of the source term (beam energy, intensity, and homogeneity). Energy characterization of a LINAC faces major technological challenges, particularly due to the high beam intensity delivered (up to several tens of Gy.min⁻¹ at the beam isocenter), its pulsed nature, and the energy of the emitted photons, which can reach up to 20 MeV.

This PhD project aims to address identified needs in the fields of radiotherapy and radiation protection, particularly regarding the characterization of the photon energy fluence spectrum from reference beams used for the high-energy calibration (E > 1.3 MeV) of a wide range of radiation protection measurement devices. It also seeks to validate spectral calculations for beams used in radiotherapy and is part of the ongoing evolution of dosimetric standards (European EMPIR SRT-S13 call for projects). This transition will require a significant improvement in the understanding of the energy spectra emitted by these systems.

The expected industrial impact of the results lies in three distinct areas:
Metrology: providing users with high-energy reference beams of metrological quality for the calibration of their respective measurement systems,
Industrial applications: deployment of instrumentation capable of operating in highly irradiating environments,
Algorithm development: design of spectrum correction algorithms adapted to the very-high-energy photon domain.

Skills required

Master’s degree (MSc) or engineering degree in physical measurements, instrumentation, or a related field.

Bibliography

J. Radiol. Prot. 44 (2024) 031506
https://doi.org/10.1088/1361-6498/ad6777

10.1016/j.apradiso.2022.110506

Keywords

Instrumentation, Monte Carlo simulations, Photon spectrometry, High dose rate, Computational methods