Optical Filter-Embedded Fiber-Optic Radiation Sensor for Ultra-High Dose Rate Electron Beam Dosimetry

Jeong, Dong-Hyeok; Lee, Manwoo; Lim, H.; Kang, Sang-Koo; Lee, Kyohyun; Lee, Sang-Jin; Kim, Hyun; Han, Woo-Kyung; Kang, T.W.; Jang, Kyoung Won

doi:10.3390/s21175840

Cited by 7 publications

(4 citation statements)

References 19 publications

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“…The sensor detected radiationinduced emissions such as fluorescence and Cherenkov radiation generated within the transmitting optical fiber. The sensor's output was measured at different distances from an electron scattering device and compared with the output of an ionization chamber and radiochromic films [73].…”

Section: Radioluminescence Cherenkov Radiation Dosimetry and Othersmentioning

confidence: 99%

FLASH Radiotherapy and the Use of Radiation Dosimeters

Siddique,

Ruda,

Chow

2023

Cancers

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Radiotherapy (RT) using ultra-high dose rate (UHDR) radiation, known as FLASH RT, has shown promising results in reducing normal tissue toxicity while maintaining tumor control. However, implementing FLASH RT in clinical settings presents technical challenges, including limited depth penetration and complex treatment planning. Monte Carlo (MC) simulation is a valuable tool for dose calculation in RT and has been investigated for optimizing FLASH RT. Various MC codes, such as EGSnrc, DOSXYZnrc, and Geant4, have been used to simulate dose distributions and optimize treatment plans. Accurate dosimetry is essential for FLASH RT, and radiation detectors play a crucial role in measuring dose delivery. Solid-state detectors, including diamond detectors such as microDiamond, have demonstrated linear responses and good agreement with reference detectors in UHDR and ultra-high dose per pulse (UHDPP) ranges. Ionization chambers are commonly used for dose measurement, and advancements have been made to address their response nonlinearities at UHDPP. Studies have proposed new calculation methods and empirical models for ion recombination in ionization chambers to improve their accuracy in FLASH RT. Additionally, strip-segmented ionization chamber arrays have shown potential for the experimental measurement of dose rate distribution in proton pencil beam scanning. Radiochromic films, such as GafchromicTM EBT3, have been used for absolute dose measurement and to validate MC simulation results in high-energy X-rays, triggering the FLASH effect. These films have been utilized to characterize ionization chambers and measure off-axis and depth dose distributions in FLASH RT. In conclusion, MC simulation provides accurate dose calculation and optimization for FLASH RT, while radiation detectors, including diamond detectors, ionization chambers, and radiochromic films, offer valuable tools for dosimetry in UHDR environments. Further research is needed to refine treatment planning techniques and improve detector performance to facilitate the widespread implementation of FLASH RT, potentially revolutionizing cancer treatment.

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Section: Radioluminescence Cherenkov Radiation Dosimetry and Othersmentioning

confidence: 99%

FLASH Radiotherapy and the Use of Radiation Dosimeters

Siddique,

Ruda,

Chow

2023

Cancers

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“…Recently, some experimental work has been done in the field of online FLASH-RT dosimetry with electrons 33,34 and protons. [35][36][37] Rahman et al 38 used a 2D dosimetry system composed of a CMOS camera and a scintillation matrix to solve pencil beam scanning (PBS) protons with a temporal resolution of 10 ms. Another study by Kanouta et al 36 improved this time resolution.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, some experimental work has been done in the field of online FLASH‐RT dosimetry with electrons 33,34 and protons 35–37 . Rahman et al 38 .…”

Section: Introductionmentioning

confidence: 99%

Technical note: Measurement of the bunch structure of a clinical proton beam using a SiPM coupled to a plastic scintillator with an optical fiber

et al. 2023

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Background: Recent proposals of high dose rate plans in protontherapy as well as very short proton bunches may pose problems to current beam monitor systems. There is an increasing demand for real-time proton beam monitoring with high temporal resolution, extended dynamic range and radiation hardness. Plastic scintillators coupled to optical fiber sensors have great potential in this context to become a practical solution towards clinical implementation. Purpose: In this work,we evaluate the capabilities of a very compact fast plastic scintillator with an optical fiber readout by a SiPM and electronics sensor which has been used to provide information on the time structure at the nanosecond level of a clinical proton beam. Materials and methods: A 3 × 3 × 3 mm 3 plastic scintillator (EJ-232Q Eljen Technology) coupled to a 3 × 3 mm 2 SiPM (MicroFJ-SMA-30035, Onsemi) has been characterized with a 70 MeV clinical proton beam accelerated in a Proteus One synchrocyclotron. The signal was read out by a high sampling rate oscilloscope (5 GS/s). By exposing the sensor directly to the proton beam, the time beam profile of individual spots was recorded. Results: Measurements of detector signal have been obtained with a time sampling period of 0.8 ns. Proton bunch period (16 ns), spot (10 µs) and interspot (1 ms) time structures could be observed in the time profile of the detector signal amplitude. From this, the RF frequency of the accelerator has been extracted, which is found to be 64 MHz. Conclusions: The proposed system was able to measure the fine time structure of a clinical proton accelerator online and with ns time resolution.

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“…Luminescence detectors offer most of those desired characteristics. 8,9 Fiber-coupled scintillators are suitable candidates that have been used before in UHDR electron, 10,11 proton 12 and x-ray beams. 13 However, they have so far only been used for measurement of the total delivered dose 10,11,13 or the spot durations 12 rather than the time-resolved dose rate.…”

Section: Introductionmentioning

confidence: 99%

Time‐resolved dose rate measurements in pencil beam scanning proton FLASH therapy with a fiber‐coupled scintillator detector system

et al. 2022

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Background:The spatial and temporal dose rate distribution of pencil beam scanning (PBS) proton therapy is important in ultra-high dose rate (UHDR) or FLASH irradiations. Validation of the temporal structure of the dose rate is crucial for quality assurance and may be performed using detectors with high temporal resolution and large dynamic range. Purpose: To provide time-resolved in vivo dose rate measurements using a scintillator-based detector during proton PBS pre-clinical mouse experiments with dose rates ranging from conventional to UHDR. Methods: All irradiations were performed at the entrance plateau of a 250 MeV PBS proton beam. A detector system with four fiber-coupled ZnSe:O inorganic scintillators and 20 μs temporal resolution was used for dose rate measurements. The system was first characterized in terms of precision and stem signal. The detector precision was determined through repeated irradiations with the same field. The stem signal contribution was quantified by irradiating two of the detector probes alongside a bare fiber (fiber without a coupled scintillator). Next, the detector system was calibrated against an ionization chamber (IC) with all four detector probes and the IC placed in a water bath at 2 cm depth. A scan pattern covering 9.6 × 9.6 cm was used. Multiple irradiations with different requested nozzle currents provided instantaneous dose rates at the detector positions in the range of 7-1270 Gy/s. The correspondence of the detector signal (in Volts) to the instantaneous dose rate (in Gy/s) was found.The instantaneous dose rate was calculated from the beam current and the spot-to-detector distance assuming a Gaussian beam profile at distances up to 8 mm from the spot. Afterwards, the calibrated system was used in vivo, in mouse experiments, where mouse legs were irradiated with a constant dose and varying field dose rates of 0.7-87.5 Gy/s. The instantaneous dose rate was measured for each delivered spot and the delivered dose was determined as the integrated instantaneous dose rate. The spot dose profile and PBS dose rate map were calculated. The dose contamination to neighbouring mice were measured together with the upper limit of the dose to the mouse body. Results: The detectors showed high precision with ≤0.4% fluctuations in the measured dose. The stem signal exceeded 10% for spots <5 mm from the This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Optical Filter-Embedded Fiber-Optic Radiation Sensor for Ultra-High Dose Rate Electron Beam Dosimetry

Cited by 7 publications

References 19 publications

FLASH Radiotherapy and the Use of Radiation Dosimeters

FLASH Radiotherapy and the Use of Radiation Dosimeters

Technical note: Measurement of the bunch structure of a clinical proton beam using a SiPM coupled to a plastic scintillator with an optical fiber

Time‐resolved dose rate measurements in pencil beam scanning proton FLASH therapy with a fiber‐coupled scintillator detector system

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