Development of a novel fibre optic beam profile and dose monitor for very high energy electron radiotherapy at ultrahigh dose rates

This study introduces the Fibre Optic FLASH Monitor (FOFM), which consists of an array of silica optical fibre-based Cherenkov sensors with a photodetector for signal readout.&#xD;Approach: Experiments were conducted at the CLEAR facility at CERN using 200 MeV and 160 MeV electrons to assess the FOFM's response linearity to UHDR (characterised with radiochromic films) required for FLASH radiotherapy. Beam profile measurements made on the FOFM were compared to those using radiochromic film and scintillating Yttrium Aluminium Garnet (YAG) screens.&#xD;Main Results: A range of photodetectors were evaluated, with a Complementary-Metal-Oxide-Semiconductor (CMOS) camera being the most suitable choice for this monitor. The FOFM demonstrated excellent response linearity from 0.9 Gy/pulse to 57.4 Gy/pulse (R² = 0.999). Furthermore, it did not exhibit any significant dependence on the energy between 160 MeV and 200 MeV nor the instantaneous dose rate. Gaussian fits applied to vertical beam profile measurements indicated that the FOFM could accurately provide pulse-by-pulse beam size measurements, agreeing within <9% and <3% of radiochromic film and YAG screen measurements, respectively.&#xD;Significance: The FOFM proves to be a promising solution for real-time beam profile and dose monitoring for UHDR VHEE beams, with a linear response in the UHDR regime. Additionally it can perform pulse-by-pulse beam size measurements, a feature currently lacking in transmission io...

Source: Physics in Medicine and Biology - March 13, 2024 Category: Physics Authors: Joseph John Bateman Emma Buchanan Roberto Corsini Wilfrid Farabolini Pierre Korysko Robert Garbrecht Larsen Alexander Malyzhenkov I ñaki Ortega Ruiz Vilde Rieker Alexander Gerbershagen Manjit Dosanjh Source Type: research