Adaptation and Dosimetric Commissioning of a Synchrotron-Based Proton Beamline for Flash Experiments

Authors

Ming Yang
Xiaochun Wang
Fada Guan
Uwe Titt
Kiminori Iga
Dadi Jiang
Takeshi Takaoka
Satoshi Tootake
Tadashi Katayose
Masumi Umezawa
Emil Schüler
Steven Frank
Steven H Lin
Narayan Sahoo
Albert C Koong
Radhe Mohan
X Ronald Zhu

Publication Date

8-5-2022

Journal

Physics in Medicine & Biology

Abstract

Objective. Irradiation with ultra-high dose rates (>40 Gy s^-1), also known as FLASH irradiation, has the potential to shift the paradigm of radiation therapy because of its reduced toxicity to normal tissues compared to that of conventional irradiations. The goal of this study was to (1) achieve FLASH irradiation conditions suitable for pre-clinicalin vitroandin vivobiology experiments using our synchrotron-based proton beamline and (2) commission the FLASH irradiation conditions achieved.

Approach. To achieve these suitable FLASH conditions, we made a series of adaptations to our proton beamline, including modifying the spill length and size of accelerating cycles, repurposing the reference monitor for dose control, and expanding the field size with a custom double-scattering system. We performed the dosimetric commissioning with measurements using an Advanced Markus chamber and EBT-XD films as well as with Monte Carlo simulations.

Main results. Through adaptations, we have successfully achieved FLASH irradiation conditions, with an average dose rate of up to 375 Gy s^-1. The Advanced Markus chamber was shown to be appropriate for absolute dose calibration under our FLASH conditions with a recombination factor ranging from 1.002 to 1.006 because of the continuous nature of our synchrotron-based proton delivery within a spill. Additionally, the absolute dose measured using the Advanced Markus chamber and EBT-XD films agreed well, with average and maximum differences of 0.32% and 1.63%, respectively. We also performed a comprehensive temporal analysis for FLASH spills produced by our system, which helped us identify a unique relationship between the average dose rate and the dose in our FLASH irradiation.

Significance.We have established a synchrotron-based proton FLASH irradiation platform with accurate and precise dosimetry that is suitable for pre-clinical biology experiments. The unique time structure of the FLASH irradiation produced by our synchrotron-based system may shed new light onto the mechanism behind the FLASH effect.

Keywords

Proton Therapy, Protons, Radiometry, Radiotherapy Dosage, Synchrotrons, FLASH, dosimetric commissioning, proton, synchrotron

DOI

10.1088/1361-6560/ac8269

PMID

35853442

PMCID

PMC9422888

PubMedCentral® Posted Date

8-5-2023

PubMedCentral® Full Text Version

Author MSS

Published Open-Access

yes