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Search Results (5)

Search Parameters:
Keywords = optical fibre scintillator

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13 pages, 929 KiB  
Article
Optimal Design of Small-Aperture Optical Terminals for Free-Space Links
by Alex Frost, Benjamin Dix-Matthews, Shane Walsh, David Gozzard and Sascha Schediwy
Photonics 2024, 11(11), 1035; https://doi.org/10.3390/photonics11111035 - 4 Nov 2024
Cited by 1 | Viewed by 1027
Abstract
We present the generalised design of low-complexity, small-aperture optical terminals intended for kilometre-scale, terrestrial, free-space laser links between fixed and dynamic targets. The design features single-mode fibre coupling of the free-space beam, assisted by a fast-steering, tip/tilt mirror that enables first-order turbulence suppression [...] Read more.
We present the generalised design of low-complexity, small-aperture optical terminals intended for kilometre-scale, terrestrial, free-space laser links between fixed and dynamic targets. The design features single-mode fibre coupling of the free-space beam, assisted by a fast-steering, tip/tilt mirror that enables first-order turbulence suppression and fine target tracking. The total power throughput over the free-space link and the scintillation index in fibre are optimised. The optimal tip/tilt correction bandwidth and range, aperture size, and focal length for a given link are derived using analytical atmospheric turbulence modelling and numerical simulations. Full article
(This article belongs to the Section Optical Communication and Network)
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13 pages, 2655 KiB  
Article
Multi-Point Sensing via Organic Optical Fibres for FLASH Proton Therapy
by Crystal Penner, Samuel Usherovich, Sophia Andru, Camille Bélanger-Champagne, Janina Hohnholz, Boris Stoeber, Cheryl Duzenli and Cornelia Hoehr
Electronics 2024, 13(11), 2211; https://doi.org/10.3390/electronics13112211 - 6 Jun 2024
Viewed by 1306
Abstract
Optical fibres are gaining popularity for relative dosimetry in proton therapy due to their spatial resolution and ability for near real-time acquisition. For FLASH proton therapy, these fibres need to handle higher dose rates and larger doses than for conventional proton dose rates. [...] Read more.
Optical fibres are gaining popularity for relative dosimetry in proton therapy due to their spatial resolution and ability for near real-time acquisition. For FLASH proton therapy, these fibres need to handle higher dose rates and larger doses than for conventional proton dose rates. We developed a multi-point fibre sensor embedded in a 3D-printed phantom which can measure the profile of a FLASH proton beam. Seven PMMA fibres of 1 mm diameter were embedded in a custom 3D-printed plastic phantom of the same density as the fibres. The phantom was placed in a proton beam with FLASH dose rates at the TRIUMF Proton Therapy Research Centre (PTRC). The sensor was exposed to different proton energies, 13.5 MeV, 19 MeV and 40.4 MeV, achieved by adding PMMA bolus in front of the phantom and three different beam currents, varying the dose rates from 7.5 to 101 Gy/s. The array was able to record beam profiles in both transverse and axial directions in relative agreement with measurements from EBT-XD radiochromic films (transverse) and Monte Carlo simulations (axial). A decrease in light output over time was observed, which might be caused by radiation damage in the matrix of the fibre and characterised by an exponential decay function. Full article
(This article belongs to the Special Issue Applications of Optical Fiber Sensors)
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13 pages, 3706 KiB  
Article
A Multi-Point Optical Fibre Sensor for Proton Therapy
by Crystal Penner, Samuel Usherovich, Sophia Andru, Camille Bélanger-Champagne, Cheryl Duzenli, Boris Stoeber and Cornelia Hoehr
Electronics 2024, 13(6), 1118; https://doi.org/10.3390/electronics13061118 - 19 Mar 2024
Cited by 3 | Viewed by 1641
Abstract
As the technology to deliver precise and very high radiotherapeutic doses with narrow margins grows to better serve patients with complex radiotherapeutic needs, so does the need for sensors and sensor systems that can reliably deliver multi-point dose monitoring and dosimetry for enhanced [...] Read more.
As the technology to deliver precise and very high radiotherapeutic doses with narrow margins grows to better serve patients with complex radiotherapeutic needs, so does the need for sensors and sensor systems that can reliably deliver multi-point dose monitoring and dosimetry for enhanced safety and access. To address this need, we investigated a novel five-point scintillator system for simultaneously sampling points across a 74 MeV proton beam with a Hamamatsu 16-channel MPPC array. We studied the response across beam widths from 25 mm down to 5 mm in diameter and in multiple depths to observe beam penumbrae and output factors as well as depth–dose. We found through comparison to ionization chambers and radiochromic film that the array is capable of measurements accurate to within 8% in the centre of proton beams from 5 to 25 mm in diameter, and within 2% at 3.5 cm depth in water. The results from three trials are repeatable after calibration to within <1%. Overall, the five optical fibre sensor system shows promise as a fast, multipoint relative dosimetry system. Full article
(This article belongs to the Special Issue Applications of Optical Fiber Sensors)
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16 pages, 1810 KiB  
Article
Characterisation of a Silicon Photomultiplier Based Oncological Brachytherapy Fibre Dosimeter
by Massimo Caccia, Agnese Giaz, Marco Galoppo, Romualdo Santoro, Micheal Martyn, Carla Bianchi, Raffaele Novario, Peter Woulfe and Sinead O’Keeffe
Sensors 2024, 24(3), 910; https://doi.org/10.3390/s24030910 - 30 Jan 2024
Cited by 7 | Viewed by 2290
Abstract
Source localisation and real-time dose verification are at the forefront of medical research in brachytherapy, an oncological radiotherapy procedure based on radioactive sources implanted in the patient body. The ORIGIN project aims to respond to this medical community’s need by targeting the development [...] Read more.
Source localisation and real-time dose verification are at the forefront of medical research in brachytherapy, an oncological radiotherapy procedure based on radioactive sources implanted in the patient body. The ORIGIN project aims to respond to this medical community’s need by targeting the development of a multi-point dose mapping system based on fibre sensors integrating a small volume of scintillating material into the tip and interfaced with silicon photomultipliers operated in counting mode. In this paper, a novel method for the selection of the optimal silicon photomultipliers to be used is presented, as well as a laboratory characterisation based on dosimetric figures of merit. More specifically, a technique exploiting the optical cross-talk to maintain the detector linearity in high-rate conditions is demonstrated. Lastly, it is shown that the ORIGIN system complies with the TG43-U1 protocol in high and low dose rate pre-clinical trials with actual brachytherapy sources, an essential requirement for assessing the proposed system as a dosimeter and comparing the performance of the system prototype against the ORIGIN project specifications. Full article
(This article belongs to the Section Physical Sensors)
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14 pages, 4380 KiB  
Article
Design and Characterisation of an Optical Fibre Dosimeter Based on Silica Optical Fibre and Scintillation Crystal
by Michal Jelinek, Ondrej Cip, Josef Lazar and Bretislav Mikel
Sensors 2022, 22(19), 7312; https://doi.org/10.3390/s22197312 - 27 Sep 2022
Cited by 4 | Viewed by 3028
Abstract
In nuclear power plants, particle accelerators, and other nuclear facilities, measuring the level of ionising gamma radiation is critical for the safety and management of the operation and the environment’s protection. However, in many cases, it is impossible to monitor ionising radiation directly [...] Read more.
In nuclear power plants, particle accelerators, and other nuclear facilities, measuring the level of ionising gamma radiation is critical for the safety and management of the operation and the environment’s protection. However, in many cases, it is impossible to monitor ionising radiation directly at the required location continuously. This is typically either due to the lack of space to accommodate the entire dosimeter or in environments with high ionising radiation activity, electromagnetic radiation, and temperature, which significantly shorten electronics’ lifetime. To allow for radiation measurement in such scenarios, we designed a fibre optic dosimeter that introduces an optical fibre link to deliver the scintillation radiation between the ionising radiation sensor and the detectors. The sensors can thus be placed in space-constrained and electronically hostile locations. We used silica optical fibres that withstand high radiation doses, high temperatures, and electromagnetic interference. We use a single photon counter and a photomultiplier to detect the transmitted scintillation radiation. We have shown that selected optical fibres, combined with different scintillation materials, are suitable for measuring gamma radiation levels in hundreds of kBq. We present the architecture of the dosimeter and its experimental characterisation with several combinations of optical fibres, detectors, and scintillation crystals. Full article
(This article belongs to the Special Issue Optical Fiber Sensors in Radiation Environments)
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