Application of a novel diamond detector for commissioning of FLASH radiotherapy electron beams

Abstract

for applications in ultrahigh-dose-per-pulse (UH-DPP) and ultrahigh-dose-rate (UH-DR) beams, as used in FLASH radiotherapy (FLASH-RT). In the present study, such socalled flashDiamond (fD) was investigated from the dosimetric point of view, under pulsed electron beam irradiation. It was then used for the commissioning of an ElectronFlash linac (SIT S.p.A., Italy) both in conventional and UH-DPP modalities. Methods: Detector calibration was performed in reference conditions, under 60 Co and electron beam irradiation. Its response linearity was investigated in UH-DPP conditions. For this purpose, the DPP was varied in the 1.2-11.9 Gy range, by changing either the beam applicator or the pulse duration from 1 to 4 µs. Dosimetric validation of the fD detector prototype was then performed in conventional modality, by measuring percentage depth dose (PDD) curves, beam profiles, and output factors (OFs). All such measurements were carried out in a motorized water phantom. The obtained results were compared with the ones from commercially available dosimeters, namely, a microDiamond, an Advanced Markus ionization chamber, a silicon diode detector, and EBT-XD GAFchromic films. Finally, the fD detector was used to fully characterize the 7 and 9 MeV UH-DPP electron beams delivered by the ElectronFlash linac. In particular, PDDs, beam profiles, and OFs were measured, for both energies and all the applicators, and compared with the ones from EBT-XD films irradiated in the same experimental conditions. Results: The fD calibration coefficient resulted to be independent from the investigated beam qualities. The detector response was found to be linear in the whole investigated DPP range. A very good agreement was observed among PDDs, beam profiles, and OFs measured by the fD prototype and reference detectors, both in conventional and UH-DPP irradiation modalities. Conclusions: The fD detector prototype was validated from the dosimetric point of view against several commercial dosimeters in conventional beams. It was proved to be suitable in UH-DPP and UH-DR conditions, for which no other commercial real-time active detector is available to date. It was shown to be a very useful tool to perform fast and reproducible beam characterizationsThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Diamond detectors for dose and instantaneous dose‐rate measurements for ultra‐high dose‐rate scanned helium ion beams

“…Two diamond detectors were utilized: a microDiamond (mD) detector (60019, PTW Freiburg) 33,34 and a so called "flashDiamond" (fD) detector prototype. 37,38 The mD detector is based on a diamond Schottky diode, whose sensitive volume is a cylinder 2.2 mm in diameter, 1 µm thick. The fD detector prototype has a structure similar to the one of the mD detectors but its design was specifically optimized for operation in UHDR and ultra-high dose-per pulse conditions.…”

“…Recently, a novel type of diamond detector prototype, the flashDiamond (fD) has been introduced to overcome nonlinearity issue observed for ion chambers and solid-state detectors in ultra-high dose-per-pulse and UHDR conditions. 37,38 In this study, a novel dosimetric system is proposed, based on mD or fD detectors, for both dose and instantaneous dose-rate measurements, aimed at a comprehensive characterization of UHDR beams. Such devices were investigated under ultra-high dose-rate helium ion beam irradiation.…”

The United States Department of Energy and National Institutes of Health Collaboration: Medical Care Advances via Discovery in Physical Sciences

“…Technology overlap opportunities include the use of scintillating crystals, gas-based detectors, photodetectors, solid-state detectors, digital silicon photomultipliers and high-speed electronics for PET, whole-body PET, SPECT, x-ray CT, and also proton/hadron therapy where particle beams are deployed. 5 Nuclear medicine camera developments rely on continuous innovation in radiation detectors, photodetectors, and electronics, which are of great interest for both the DOE and NIH communities. High-speed photodetectors developed for particle physics such as large area picosecond photodetectors (LAPPD) and low gain avalanche detectors (LGADs) could advance nuclear medicine imaging.…”

“…Often PET and SPECT systems are combined in hybrid systems for anatomical correlation and attenuation/scatter corrections with x‐ray computed tomography (x‐ray CT) scanners and occasionally magnetic resonance imaging (MRI). Technology overlap opportunities include the use of scintillating crystals, gas‐based detectors, photodetectors, solid‐state detectors, digital silicon photomultipliers and high‐speed electronics for PET, whole‐body PET, SPECT, x‐ray CT, and also proton/hadron therapy where particle beams are deployed 5 . Nuclear medicine camera developments rely on continuous innovation in radiation detectors, photodetectors, and electronics, which are of great interest for both the DOE and NIH communities.…”

Multi‐institutional consensus on machine QA for isochronous cyclotron‐based systems delivering ultra‐high dose rate (FLASH) pencil beam scanning proton therapy in transmission mode

“…9,10 However, as demonstrated by Yang et al and Lee et al, 11,12 the charge saturation for specific ionization chambers appears to be less significant for quasi-continuous proton beams with nozzle currents of up to 215 nA even when standard bias voltage is used. Moreover, novel detectors have been designed and evaluated, [12][13][14] but further developments are still required to improve the characterization and QA of the UHDR proton beam.…”