Feasibility of prototype diamond detectors for pulsed UHDR PBS small-field proton dosimetry for proton FLASH experiments

At a Glance

Metadata	Details
Publication Date	2025-09-02
Journal	Physics in Medicine and Biology
Authors	Jufri Setianegara, Aoxiang Wang, N. Gérard, Jarrick Nys, Marek Szczepański
Institutions	Cyclotron (Netherlands), University of Kansas Medical Center

Abstract

Abstract Objective. This study aims to investigate the responses of prototype diamond detectors under pulsed ultra-high dose rates (UHDRs) pencil-beam-scanning (PBS) protons from a compact proton synchrocyclotron (IBA Proteus®ONE) for small-field UHDR dosimetry. Approach . flashDiamond detectors (fDs) were cross-calibrated with their relative proton responses characterized at conventional dose rates (CONV). Then, absolute UHDR dosimetry was performed and small-field response assessed. These experiments were also conducted with Razor Diode and microdiamond detectors (mDs) for cross-reference. Cross-calibrations were performed against an ADCL-calibrated PPC05 plane-parallel ionization chamber with 59.23 cGy nC −1 calibration coefficients. fD’s linearity, dose-rate, energy, and linear-energy-transfer (LET) responses were assessed under CONV protons. Pulsed UHDR PBS protons of 228 MeV were produced from a medical proton synchrocyclotron (IBA Proteus®ONE) for 1.5 × 1.5-3.0 × 3.0 cm 2 square fields. Nominal absolute UHDR dosimetry was performed at 3 × 3 cm 2 field sizes with relative responses at smaller fields benchmarked against it. Main results . fD had 28.6 ± 0.1 cGy nC −1 sensitivities under CONV protons and were linear in response with dose-rate independence within ±0.50%. fD were similar to mD in proton energy and LET responses. However, there is an over-response of approximately 5.49%, 6.51% and 13.7% at the 226, 150 and 70 MeV Bragg peaks respectively. Under pulsed proton UHDR irradiation (0.80% s.t.d, 32.6 ± 0.5 cGy dose-per-pulse), fD responded within ±1% as PPC05 with negligible saturation. fD agreed within ±1% with other comparable small-field detectors under small-field UHDR beams and within ±2% of RayStation treatment planning system calculations. There is negligible partial volume averaging with fDs. Significance . Novel fD detectors did not saturate under pulsed UHDR PBS proton irradiation. Their miniscule active crystals make them suitable for small-field dosimetry but render them relatively insensitive compared to mDs. When cross-calibrated, they are suitable for absolute small-field UHDR dosimetry or for relative exit dosimetry monitoring purposes during UHDR radiobiological experiments.

Tech Support

Original Source

DOI: https://doi.org/10.1088/1361-6560/ae023b

References

2024 - Multi-institutional audit of FLASH and conventional dosimetry with a 3D printed anatomically realistic mouse phantom [Crossref]
2023 - The current status of FLASH particle therapy: a systematic review [Crossref]
2025 - Whole abdominal pencil beam scanned proton FLASH increases acute lethality [Crossref]
2024 - Preclinical ultra-high dose rate (FLASH) proton radiation therapy system for small animal studies [Crossref]
2022 - Determination of the ion collection efficiency of the Razor Nano Chamber for ultra-high dose-rate electron beams [Crossref]
2024 - Mechanisms of action in FLASH radiotherapy: a comprehensive review of physicochemical and biological processes on cancerous and normal cells [Crossref]
2021 - Spread-out Bragg peak proton FLASH irradiation using a clinical synchrocyclotron: proof of concept and ion chamber characterization [Crossref]
2020 - Feasibility of proton FLASH irradiation using a synchrocyclotron for preclinical studies [Crossref]
2024 - FLASH radiotherapy for the treatment of symptomatic bone metastases in the thorax (FAST-02): protocol for a prospective study of a novel radiotherapy approach [Crossref]
2023 - Definition of dose rate for FLASH pencil-beam scanning proton therapy: a comparative study [Crossref]