Characterization of a modified clinical linear accelerator for ultra-high dose rate electron beam delivery

TL;DR

This paper describes modifications to a clinical linear accelerator enabling ultra-high dose rate electron beam delivery, with detailed dosimetry characterization, supporting advanced radiobiology experiments and technological testing in UHDR research.

Contribution

The study presents hardware and software modifications to a clinical LINAC for UHDR electron beams, with comprehensive dosimetry and stability assessments, advancing UHDR radiobiology research capabilities.

Findings

Dose per pulse ranged from 0.6 Gy to tens of Gy

Average dose rate reached up to 300 Gy/s

Beam stability and repeatability confirmed

Abstract

Irradiations at Ultra High Dose Rate (UHDR) regimes, exceeding 40 Gy/s in single fractions lasting less than 200 ms, have shown an equivalent antitumor effect compared to conventional radio-therapy with reduced harm to normal tissues. This work details the hardware and software modi-fications implemented to deliver 10 MeV UHDR electron beams with a Linear Accelerator Elekta SL 18 MV and the beam characteristics obtained. GafChromic EBT XD films and an Advanced Markus chamber were used for the dosimetry characterization, while a silicon sensor assessed the machine's beam pulses stability and repeatability. Dose per pulse, average dose rate and instantaneous dose rate in the pulse were evaluated for four experimental settings, varying the source-to-surface dis-tance and the beam collimation, i.e. with and without the use of a cylindrical applicator. Results showed dose per pulse from 0.6 Gy to a few tens of Gy and average dose rate up to 300 Gy/s. The obtained results demonstrate the possibility to perform in-vitro radiobiology experiments and test of new technologies for beam monitoring and dosimetry at the upgraded LINAC, thus contributing to the electron UHDR research field.