Ultra-high dose rate dosimetry for pre-clinical experiments with mm-small proton fields

Togno, Michele; Nesteruk, Konrad Pawel; Schäfer, Robert Michael; Psoroulas, S.; Meer, D.; Großmann, Martin; Christensen, Jeppe Brage; Yukihara, E.G.; Lomax, Anthony; Weber, Damien Charles; Safai, Sairos

doi:10.1016/j.ejmp.2022.10.019

Cited by 15 publications

(24 citation statements)

References 51 publications

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“…At PSI Gantry1, different detectors have been recently tested up to several kGy/s (29, 30). To prepare for the biological studies, we verified that the measured field dose was reproducible and consistent between EBT3 Gafchromic films, Advanced Markus ion-chambers and synthetic microDiamonds, after proper characterization of the detectors (25).…”

Section: Discussionmentioning

confidence: 77%

“…In conditions using CONV, both detectors are cross-calibrated to a reference chamber traceable to the Swiss primary standard laboratory METAS. The detector responses at different dose rates were previously characterized by Togno et al (25) and corrections to detectors reading were considered accordingly. The overall combined uncertainty on absorbed dose to water in proton beams was 2.5 % (k=1) and 1.9 % (k=1) for EBT3 films and PTW microDiamond, respectively.…”

Section: Irradiation Devicesmentioning

confidence: 99%

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Dosimetric and biologic intercomparison between electron and proton FLASH beams

Almeida

Togno

Ballesteros-Zebadúa

et al. 2023

Preprint

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Background and purpose: The FLASH effect has been validated in different preclinical experiments with electrons (eFLASH) and protons (pFLASH) operating at a mean dose rate above 40 Gy/s. However, no systematic intercomparison of the FLASH effect produced by e vs. pFLASH has yet been performed and constitutes the aim of the present study. Materials and methods: The electron eRT6/Oriatron/CHUV/5.5 MeV and proton Gantry1/PSI/170 MeV were used to deliver conventional (0.1 Gy/s eCONV and pCONV) and FLASH (above 100 Gy/s eFLASH and pFLASH) irradiation. Protons were delivered in transmission. Dosimetric and biologic intercomparisons were performed with previously validated models. Results: Doses measured at Gantry1 were in agreement (+/- 2.5%) with reference dosimeters calibrated at CHUV/IRA. The neurocognitive capacity of e and pFLASH irradiated mice was indistinguishable from the control while both e and pCONV irradiated cohorts showed cognitive decrements. Complete tumor response was obtained with the two beams and was similar between e and pFLASH vs. e and pCONV. Tumor rejection was similar indicating that T-cell memory response is beam-type and dose-rate independent. Conclusion: Despite major differences in the temporal microstructure, this study shows that dosimetric standards can be established. The sparing of brain function and tumor control produced by the two beams were similar, suggesting that the most important physical parameter driving the FLASH effect is the overall time of exposure which should be in the range of hundreds of milliseconds for WBI in mice. In addition, we observed that immunological memory response is similar between electron and proton beams and is independent off the dose rate.

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Section: Discussionmentioning

confidence: 77%

Section: Irradiation Devicesmentioning

confidence: 99%

Dosimetric and biologic intercomparison between electron and proton FLASH beams

Almeida

Togno

Ballesteros-Zebadúa

et al. 2023

Preprint

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“…The Aarhus University group in Denmark recently showed that ZnSe:O crystals can be successfully used for measurements of the time structure of FLASH pencil scanning proton beams with a dosimetry setup similar to the one proposed in this work 27 . The results reported in Figure 6 show that the proposed detection system provides beam profile measurements at sub-millimeter level 28 . This turns to be particularly important for spatial fractionated radiation therapy applications such as minibeam radiation therapy 29 .…”

Section: Discussionmentioning

confidence: 90%

Ultra-high dose rate dosimetry with miniaturized scintillation detectors coupled to optical fibers

Casolaro

Dellepiane

Gottstein

et al. 2023

Preprint

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FLASH radiotherapy is a novel radiation delivery modality, generally considered a potential breakthrough in cancer care. With ultra-high dose rates (>40 Gy/s) delivered in fractions of a second, FLASH is characterized by unique irradiation conditions which bring along new challenges in dosimetry and beam monitoring. This article reports on the validation of innovative detection systems based on sub-millimeter-sized fast scintillation detectors coupled to optical fibers. We characterized different scintillators, namely Gadolinium Aluminium Gallium Garnet (GAGG), yttrium doped barium fluoride (Y-BaF2), and polystyrene, by studying their response to ultra-high dose rate 18 MeV proton beams. Beam tests were carried out at the Bern medical cyclotron, providing beams for multidisciplinary research activities and commercial radioisotope production, that we characterized for ultra-high dose rates irradiations. The possibility of changing the scintillator to be coupled to the optical fiber gives great flexibility to the system, by allowing to measure proton dose rates up 10.4 kGy/s and mm-small fields with high time resolution. The measurements reported in this paper were performed at a sampling rate of 20 kHz, although data acquisition up to 10 MHz is possible. The developed detection system can be successfully used to measure ultra-high dose rates and it can be further optimized to address specific and essential issues of FLASH radiation therapy, including quality assurance, real-time beam monitoring and in-vivo dosimetry.

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“…PTW microDiamond detectors (mD) 33,34 have already been successfully tested under high LET conditions for standard dose-rate delivery (SDR). 35,36 Compared to other detectors they present the advantage to be tissue equivalent, with an excellent time and spatial resolution. 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.…”

Section: Introductionmentioning

confidence: 99%

“…Several detectors are envisioned to work for FLASH radiation therapy, 30–32 from strip detectors to diamond detectors. PTW microDiamond detectors (mD) 33,34 have already been successfully tested under high LET conditions for standard dose‐rate delivery (SDR) 35,36 . Compared to other detectors they present the advantage to be tissue equivalent, with an excellent time and spatial resolution.…”

Section: Introductionmentioning

confidence: 99%

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

Tessonnier,

Verona‐Rinati,

Rank

et al. 2023

Medical Physics

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BackgroundThe possible emergence of the FLASH effect—the sparing of normal tissue while maintaining tumor control—after irradiations at dose‐rates exceeding several tens of Gy per second, has recently spurred a surge of studies attempting to characterize and rationalize the phenomenon. Investigating and reporting the dose and instantaneous dose‐rate of ultra‐high dose‐rate (UHDR) particle radiotherapy beams is crucial for understanding and assessing the FLASH effect, towards pre‐clinical application and quality assurance programs.PurposeThe purpose of the present work is to investigate a novel diamond‐based detector system for dose and instantaneous dose‐rate measurements in UHDR particle beams.MethodsTwo types of diamond detectors, a microDiamond (PTW 60019) and a diamond detector prototype specifically designed for operation in UHDR beams (flashDiamond), and two different readout electronic chains, were investigated for absorbed dose and instantaneous dose‐rate measurements. The detectors were irradiated with a helium beam of 145.7 MeV/u under conventional and UHDR delivery. Dose‐rate delivery records by the monitoring ionization chamber and diamond detectors were studied for single spot irradiations. Dose linearity at 5 cm depth and in‐depth dose response from 2 to 16 cm were investigated for both measurement chains and both detectors in a water tank. Measurements with cylindrical and plane‐parallel ionization chambers as well as Monte‐Carlo simulations were performed for comparisons.ResultsDiamond detectors allowed for recording the temporal structure of the beam, in good agreement with the one obtained by the monitoring ionization chamber. A better time resolution of the order of few μs was observed as compared to the approximately 50 μs of the monitoring ionization chamber. Both diamonds detectors show an excellent linearity response in both delivery modalities. Dose values derived by integrating the measured instantaneous dose‐rates are in very good agreement with the ones obtained by the standard electrometer readings. Bragg peak curves confirmed the consistency of the charge measurements by the two systems.ConclusionsThe proposed novel dosimetric system allows for a detailed investigation of the temporal evolution of UHDR beams. As a result, reliable and accurate determinations of dose and instantaneous dose‐rate are possible, both required for a comprehensive characterization of UHDR beams and relevant for FLASH effect assessment in clinical treatments.

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Ultra-high dose rate dosimetry for pre-clinical experiments with mm-small proton fields

Cited by 15 publications

References 51 publications

Dosimetric and biologic intercomparison between electron and proton FLASH beams

Dosimetric and biologic intercomparison between electron and proton FLASH beams

Ultra-high dose rate dosimetry with miniaturized scintillation detectors coupled to optical fibers

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

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