Faculty, Staff and Student Publications

Language

English

Publication Date

4-1-2025

Journal

International Journal of Radiation Oncology, Biology, Physics

DOI

10.1016/j.ijrobp.2024.11.092

PMID

39615658

PMCID

PMC12335921

PubMedCentral® Posted Date

8-11-2025

PubMedCentral® Full Text Version

Author MSS

Abstract

Purpose: Scintillation dosimetry has promising qualities for ultra-high-dose-rate (UHDR) radiation therapy (RT), but no system has shown compatibility with mean dose rates (DR¯) above 100 Gy/s and doses per pulse (Dp) exceeding 1.5 Gy typical of UHDR (FLASH)-RT. The aim of this study was to characterize a novel scintillation dosimetry system with the potential of accommodating UHDRs.

Methods and materials: We undertook a thorough dosimetric characterization of the system on an UHDR electron beamline. The system's response as a function of dose, DR¯, Dp, and the pulse dose-rate (DRp) was investigated, as was the system's dose sensitivity (signal per unit dose) as a function of dose history. The capabilities of the system for time-resolved dosimetric readout were also evaluated.

Results: Within a tolerance of ±3%, the system exhibited dose linearity and was independent of DR¯ and Dp within the tested ranges of 1.8 to 1341 Gy/s and 0.005 to 7.68 Gy, respectively. A 6% reduction in the signal per unit dose was observed as DRp was increased from 8.9e4 to 1.8e6 Gy/s. The dose delivered per integration window of the continuously sampling photodetector had to remain between 0.028 and 11.56 Gy to preserve a stable signal response per unit dose. The system accurately measured Dp of individual pulses delivered at up to 120 Hz. The day-to-day variation of the signal per unit dose in a reference setup varied by up to ±13% but remained consistent (< ±2%) within each treatment day and showed no signal loss as a function of dose history.

Conclusions: With daily calibrations and DRp-specific correction factors, the system reliably provides real-time, millisecond-resolved dosimetric measurements of pulsed conventional and UHDR beams from typical electron linacs, marking an important advancement in UHDR dosimetry and offering diverse applications to FLASH-RT and related fields.

Keywords

Scintillation Counting, Radiotherapy Dosage, Time Factors, Humans, Particle Accelerators, Radiometry

Published Open-Access

yes

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