Advanced characterization of an optical fibre sensor system based on an MPPC detector for measurement of X-ray radiation in clinical linacs

Chen, Lingxia; Ong, Yong Sheng; Chen, Shuilin; O'Keeffe, Sinéad; Gillespie, Sean; Woulfe, Peter; Jiang, Benxue; Grout, Ian; Lewis, Elfed

doi:10.1016/j.sna.2020.112129

Cited by 1 publication

(1 citation statement)

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“…This prompts the suggestion that real-time dosimetric measurements of the individual pulses be part of a more robust QA regime, inclusive of conventional EBRT treatments, providing a strengthened basis for accurate monitoring of linac beam quality and delivered dose 10,3,11,8 . Currently, while the investigation described in this article is limited to working with clinical linacs at conventional dose rates, the radioluminescence (RL) based optical ber-based dosimetry system previously developed by the authors of this article offers great potential for real-time detection of doserate errors, a prime objective of this investigation 12,13 . A continuous dose-delivery 1 MeV electron beam industrial irradiator has previously been used to demonstrate the resilience of optical ber sensors against irradiation damage, handling doses of up to 70 kGy 14 as well as their ability to handle an elevated dose per pulse.…”

Section: Introductionmentioning

confidence: 99%

The high dose rate sensing potential of a radiotherapy optical fiber dosimeter

Basaif¹,

Oresegun²,

Tarif³

et al. 2023

Preprint

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A perceived need exists for real-time dosimeters offering pulse-by-pulse temporal resolution to validate the delivery of the prescribed dose from clinical electron linear accelerators (linacs). In the case of linacs working at conventional (100–600 cGy/min) dose rates and operating in the bremsstrahlung mode, radioluminescence-emitting Ge-doped silica optical fibers have been shown to satisfy such demand. Ge-doped silica optical fiber scintillators measurements are made for a linac operating in the electron mode, delivering at dose rates up to 600 cGy/min. The radioluminescence response of the material as a function of dose has been measured using a Photomultiplier Tube (PMT) with a photon-counting circuit capable of 1-200 µs gating time, demonstrating dose linearity (R2 = 0.99971). Time-resolved radiation dosimetry measurements for a wide range of electron beam energies (6, 9, 12, 15 and 18 MeV) are reported. Measurements using a Multi Pixel Photon Counter (MPPC) connected to an oscilloscope shows the absence of saturation in the time resolved signal, freedom from performance limitations of residual memory or afterglow effects. Individual pulses at different energies have been analysed in terms of rise- and decay-times. While obtaining a qualitative assessment of the variation in pulse sub-structure, the variations likely arising from internal pulse manipulation for handling linac power delivery. The results point not only to the use of Ge-doped optical fiber scintillator in time-resolved dosimetry at conventional dose rates but also potential for use at the greater dose-rates of FLASH radiotherapy.

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