Point scintillator dosimetry in ultra-high dose rate electron “FLASH” radiation therapy: A first characterization

Vanreusel, Verdi; Gasparini, Alessia; Galante, Federica; Mariani, Giulia; Pacitti, M.; Cociorb, Madalina; Giammanco, A.; Reniers, Brigitte; Reulens, N.; Shonde, Tunde Blessed; Vallet, Hugo; Vandenbroucke, D.; Peeters, Marc; Leblans, Paul; Ma, Biwu; Felici, G.; Verellen, Dirk; Nascimento, Luana de Freitas

doi:10.1016/j.ejmp.2022.10.005

Cited by 19 publications

(10 citation statements)

References 29 publications

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“…The integrated RL response from organic scintillators shows good reproducibility and linearity against absorbed dose [9,11]. Linearity is also found for inorganic scintillators, even if a dose-rate dependent sensitivity can be the case [4]. Systems using plastic scintillators and fibers have the advantage of being almost tissue equivalent, contrary to those based on inorganic scintillators that are made of high-Z materials (the effective atomic number Z of the scintillator has to be as close as possible to that of water, 7.42, so that the way in which dose absorption depends on the particle energy is similar in the dosimeter and soft human tissue).…”

Section: Introductionmentioning

confidence: 99%

“…Third, RL dosimeters can be small in size, thus allowing a good spatial resolution, and coupled to flexible, easy-to-handle optical fiber cables. It is now recognized that realtime luminescent dosimeters have a key role to play in the measurement of UHDR and the implementation of flash RT [3,4,7,9].…”

Section: Introductionmentioning

confidence: 99%

“…The potential of fiber-based systems exploiting scintillation for medical dosimetry has been studied for about 20 years. Research has been essentially directed to plastic [9][10][11] or inorganic [4,10,11] scintillators, most often coupled to plastic (PMMA) transport fibers guiding luminescence to a photodetector. Such systems are typically 0.5-1 mm in diameter.…”

Section: Introductionmentioning

confidence: 99%

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Silica-based scintillators: basic properties of radioluminescence kinetics

Grandvillain,

Vidal,

Hérault

et al. 2024

J. Phys.: Condens. Matter

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Radioluminescent silica-based fiber dosimeters offer great advantages for designing miniaturized realtime sensors for high dose-rate dosimetry. Rise and fall kinetics of their response must be properly understood to better assess their performances in terms of measurement speed and repeatability. A standard model of radioluminescence (RL) has already been quantitatively validated for doped silica glasses, but beyond conclusive comparisons with specific experiments, a comprehensive understanding of the processes and parameters determining transient and equilibrium kinetics of RL is still lacking. We analyse in detail the kinetics inherent in the standard RL model. Several asymptotical regimes in the RL growth are demonstrated in the case of a pristine sample (succesive quadratic, linear and power-law time dependencies before the plateau is reached). We show how this situation is modified when a pre-irradiation partly fills traps beforehand. RL growth is then greatly accelerated because of the pre-formation of recombination centers from dopant ions, but not due to pre-filling of trapping levels. In all cases, the RL intensity eventually tends to a constant level equal to the pair generation rate, long before all carrier densities themselves reach equilibrium. This occurs late under irradiation, when deep traps get to saturation. The fraction of dopants converted into recombination centers is then ‘frozen’ at a lower level the smaller the density of deep traps. Controlling RL kinetics through the engineering of material traps is not an option. Pre-irradiation appears to be the simplest way to obtain accelerated and repeatable kinetics.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Silica-based scintillators: basic properties of radioluminescence kinetics

Grandvillain,

Vidal,

Hérault

et al. 2024

J. Phys.: Condens. Matter

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“…Although FLASH-RT is promising in preclinical studies, this new technology still faces many challenges. One of the most challenging issues is accurate dose measurement (Vanreusel et al 2022). The radiobiological mechanism of FLASH effect has yet to be fully understood, so more experiments are needed to verify it.…”

Section: Introductionmentioning

confidence: 99%

“…For now, the ionization chamber (IC) has the advantages of good dose linearity, irradiation resistance and easy to operate. So the golden standard used for dosimetry in clinical radiotherapy is the IC (Vanreusel et al 2022). However, the IC will suffer a severe recombination effect and lead to the reduction of space charge due to the ultra-high dose rate generated.…”

Section: Introductionmentioning

confidence: 99%

Preliminary study of low-pressure ionization chamber for online dose monitoring in FLASH carbon ion radiotherapy

Lang,

Hu,

Zhao

et al. 2024

Phys. Med. Biol.

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Abstract：The FLASH effect of carbon ion therapy has recently attracted significant attention from the scientific community. However, the radiobiological mechanism of the effect and the exact therapeutic conditions are still under investigation. Therefore, the dosimetry accuracy is critical for testing hypotheses about the effect and quantifying FLASH Radiotherapy. In this paper, the FLASH ionization chamber at low-pressure was designed, and its dose rate dependence was verified with the Faraday cup. In addition, the dose response was tested under the air pressure of the ionization chamber of 10 mbar, 80 mbar and 845 mbar, respectively. The results showed that when the pressure was 10 mbar, the dose linearity was verified and calibrated at the dose rate of ~50 Gy/s, and the residuals were less than 2%. In conclusion, the FLASH ionization chamber is a promising instrument for online dose monitoring.Keywords: FLASH; Low-pressure ionization chamber; Carbon ion therapy; Dosimetry

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Characterization of a commercial plastic scintillator for electron FLASH dosimetry

Oh,

Hyun,

Gallagher

et al. 2024

J Applied Clin Med Phys

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PurposeThis study investigated the potential of a commercially available plastic scintillator, the Exradin W2, as a real‐time dosimeter for ultra‐high‐dose‐rate (UHDR) electron beams. This work aimed to characterize this system's performance under UHDR conditions and addressed limitations inherent to other conventional dosimetry systems.Methods and materialsWe assessed the W2's performance as a UHDR electron dosimeter using a 16 MeV UHDR electron beam from the FLASH research extension (FLEX) system. Additionally, the vendor provided a beta firmware upgrade to better handle the processing of the high signal generated in the UHDR environment. We evaluated the W2 regarding dose‐per‐pulse, pulse repetition rate, charge versus distance, and pulse linearity. Absorbed dose measurements were compared against those from a plane‐parallel ionization chamber, optically stimulated luminescent dosimeters and radiochromic film.ResultsWe observed that the 1 × 1 mm W2 scintillator with the MAX SD was more suitable for UHDR dosimetry compared to the 1 × 3 mm W2 scintillator, capable of matching film measurements within 2% accuracy for dose‐per‐pulse up to 3.6 Gy/pulse. The W2 accurately ascertained the inverse square relationship regarding charge versus virtual source distance with R2 of ∼1.00 for all channels. Pulse linearity was accurately measured with the W2, demonstrating a proportional response to the delivered pulse number. There was no discernible impact on the measured charge of the W2 when switching between the available repetition rates of the FLEX system (18–180 pulses/s), solidifying consistent beam output across pulse frequencies.ConclusionsThis study tested a commercial plastic scintillator detector in a UHDR electron beam, paving the way for its potential use as a real‐time, patient‐specific dosimetry tool for future FLASH radiotherapy treatments. Further research is warranted to test and improve the signal processing of the W2 dosimetry system to accurately measure in UHDR environments using exceedingly high dose‐per‐pulse and pulse numbers.

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Point scintillator dosimetry in ultra-high dose rate electron “FLASH” radiation therapy: A first characterization

Cited by 19 publications

References 29 publications

Silica-based scintillators: basic properties of radioluminescence kinetics

Silica-based scintillators: basic properties of radioluminescence kinetics

Preliminary study of low-pressure ionization chamber for online dose monitoring in FLASH carbon ion radiotherapy

Characterization of a commercial plastic scintillator for electron FLASH dosimetry

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