Evidence map›Paper›PMID 42108226›Full record

ArticleMedical physics2026

Time-resolved point dosimetry for spread-out Bragg-peak proton FLASH using fibre-coupled scintillators.

Sky R Steenholdt, Jacob G Johansen, Eleni Kanouta, Per R Poulsen

Abstract read
In one paragraph

Article in Medical physics, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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1 · What the graph read from it

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2 · The registry

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4 · The record

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5 · Who and what money

Authors and funding

4 authors.

Sky R SteenholdtDanish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark.
Jacob G JohansenDanish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark.
Eleni KanoutaDanish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark.
Per R PoulsenDanish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark.

Funding

Danish Cancer Society R353-A20702Danish Cancer Society R374-A22587Novo Nordisk Fonden NNF20OC0065282Varian Medical Systems
6 · The paper itself

Abstract

backgroundIn FLASH radiotherapy, the dose is delivered using ultra-high dose rates (UHDR), which are approximately 100 times higher than those used for conventional (CONV) treatments. This has shown promise in sparing normal tissue while maintaining tumour control. Proton beams, particularly in the spread-out Bragg peak (SOBP), offer a favourable depth-dose profile for sparing healthy tissue. However, quality assurance for FLASH requires time-resolved dosimetry to capture the temporal structure of pencil beam scanning delivery. Fibre-coupled scintillating detectors have been used both in electron and photon UHDR beams, and have been applied in the proton beam entrance plateau. Extending their use to the SOBP requires careful calibration to address quenching and water-inequivalent response near the Bragg peak. PURPOSE: To calibrate and validate a fibre-coupled inorganic scintillator detector system for accurate, time-resolved point dosimetry in the SOBP for UHDR proton beams, which will enable preclinical and in-vivo FLASH studies with robust dosimetric and geometric verification.

methodsExperiments were conducted using a clinical proton PBS beam line. A 2D range modulator generated a 5 cm SOBP from a mono-energetic beam. Four ZnSe:O scintillator probes coupled to optical fibres were read out by silicon photomultipliers at 50 kHz. An ionisation chamber provided reference dose measurements. The calibration included determining a signal dependent saturation factor of the silicon photomultiplier

resultsA saturation multiplier of up to 55% was observed across all four probes. The depth-dependent under-response reached up to 12% at the distal SOBP edge. Both effects were successfully corrected for through fitting simple functions. The validation in the SOBP demonstrated that the calibration achieved positional stability within

conclusionsThe developed calibration method enables accurate, time-resolved dosimetry in UHDR proton SOBP beams, allowing for the separation of saturation and quenching corrections. The fibre-coupled scintillator system demonstrated high precision in both dose and geometry, making it suitable for quality assurance in preclinical FLASH studies. This approach streamlines recalibration, reducing beam time requirements, and supports routine monitoring of PBS-delivered proton FLASH treatments in complex depth-dose scenarios.

Indexed as

Optical FibersProton TherapyRadiometryScintillation CountingCalibrationProtonsRadiotherapy DosageTime FactorsProtons

Identifiers

PMID42108226
PMCPMC13158171

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.