Evaluation of silicon strip detectors in transmission mode for online beam monitoring in microbeam radiation therapy at the Australian Synchrotron

Abstract

Successful transition of synchrotron-based microbeam radiation therapy (MRT) from pre-clinical animal studies to human trials is dependent upon ensuring that there are sufficient and adequate measures in place for quality assurance purposes. Transmission detectors provide researchers and clinicians with a real-time quality assurance and beam-monitoring instrument to ensure safe and accurate dose delivery. In this work, the effect of transmission detectors of different thicknesses (10 and 375 µm) upon the photon energy spectra and dose deposition of spatially fractionated synchrotron radiation is quantified experimentally and by means of a dedicated Geant4 simulation study. The simulation and experimental results confirm that the presence of the 375 µm thick transmission detector results in an approximately 1–6% decrease in broad-beam and microbeam peak dose. The capability to account for the reduction in dose and change to the peak-to-valley dose ratio justifies the use of transmission detectors as thick as 375 µm in MRT provided that treatment planning systems are able to account for their presence. The simulation and experimental results confirm that the presence of the 10 µm thick transmission detector shows a negligible impact (<0.5%) on the photon energy spectra, dose delivery and microbeam structure for both broad-beam and microbeam cases. Whilst the use of 375 µm thick detectors would certainly be appropriate, based upon the idea of best practice the authors recommend that 10 µm thick transmission detectors of this sort be utilized as a real-time quality assurance and beam-monitoring tool during MRT.

Hydrogenated amorphous silicon high flux x-ray detectors for synchrotron microbeam radiation therapy

“…However, the energy dependence of the combination of fibre-optic and OPD dosimeters are heavily dependent on the plastic scintillator material used (Archer et al 2018, Posar et al 2020, Large Posar et al 2021. Silicon strip detectors are an attractive solution for MRT dosimetry, with spatial resolution able to resolve individual microbeams and dosimetric response closely matching commercially available detectors (Lerch et al 2011, Wong et al 2011, Petasecca et al 2012, Davis et al 2022. A promising solution for MRT dosimetry is also represented by single-crystal diamond dosimeters such as the commercially available PTW microDiamond 60019, which has demonstrated exceptional performances for dosimetry of synchrotron microbeams.…”

“…The experimental dosimetric characterisations summarised in this work are performed on an innovative a-Si:H device structure based on a selection of CSC deposited on an intrinsic amorphous substrate (Menichelli et al 2021). The dosimetry protocols adopted are the ones developed for synchrotron-based radiotherapy and MRT as outlined in the works of Prezado et al (2011) and Davis et al (2022).…”