X-ray microbeam measurements with a high resolution scintillator fibre-optic dosimeter

Archer, James; Li, Enbang; Petasecca, Marco; Dipuglia, Andrew; Cameron, Matthew; Stevenson, Andrew W.; Hall, Christopher; Häusermann, Daniel M.; Rosenfeld, Anatoly B.; Lerch, Michael L. F

doi:10.1038/s41598-017-12697-6

Cited by 20 publications

(18 citation statements)

References 18 publications

(18 reference statements)

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“…Further, this effect is more significant with larger field heights. It is not due to high dose rate due to the effect also being seen at much lower dose rates 11,31 . The reduced discrepancy between the FOD signal and ionisation chamber, compared to the fibre-only signal, suggests that the discrepancy is minimal in the scintillator itself.…”

Section: Resultsmentioning

confidence: 97%

“…The scintillation and SiPM collection efficiency spectra can be found in Archer et al . 31 . As the scintillator is not covered, experiments must be done in darkness to minimise the amount of ambient light entering the optical fibre.…”

Section: Methodsmentioning

confidence: 99%

“…We have previously tested FODs with MRT beams that have a spatial resolution of 50 μ m 31 and 20 μ m 11 . In this work we demonstrate a FOD with a spatial resolution of 10 μ m, the highest of a plastic scintillator detector found in the literature.…”

Section: Introductionmentioning

confidence: 99%

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High spatial resolution scintillator dosimetry of synchrotron microbeams

Archer

Davis

et al. 2019

Sci Rep

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Microbeam radiation therapy is a novel pre-clinical external beam therapy that uses high-brilliance synchrotron X-rays to deliver the necessary high dose rates. The unique conditions of high dose rate and high spatial fractionation demand a new class of detector to experimentally measure important beam quality parameters. Here we demonstrate the highest spatial resolution plastic scintillator fibre-optic dosimeter found in the literature to date and tested it on the Imaging and Medical Beam-Line at the Australian Synchrotron in a X-ray beam where the irradiation dose rate was 4435 Gy/s. With a one-dimensional spatial resolution of 10 μ m the detector is able to resolve the individual microbeams (53.7 ± 0.4 μ m wide), and measure the peak-to-valley dose ratio to be 55 ± 17. We also investigate the role of radioluminescence in the optical fibre used to transport the scintillation photons, and conclude that it creates a significant contribution to the total light detected.

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Section: Resultsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

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High spatial resolution scintillator dosimetry of synchrotron microbeams

Archer

Davis

et al. 2019

Sci Rep

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“…In this case, the use of narrow optical fibers may solve problems of probe compactness encountered with plastic fibers in intracorporeal dosimetry. The resulting two-fiber dosimeters do indeed remain at least two times narrower than the single-fiber probes developed so far [13][14][15]. Complex signal processing aimed at removing Cerenkov signal in a single-fiber dosimeter architecture [16][17][18] could thus be avoided.…”

Section: Resultsmentioning

confidence: 99%

Miniaturized fiber dosimeter of medical ionizing radiations on a narrow optical fiber

Suárez¹,

Lim²,

Robillot³

et al. 2019

Opt. Express

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Fiber dosimeters have recently drawn much interest for measuring in vivo and in real time the dose of medical radiations. This paper presents the first miniaturized fiber dosimeter integrated at the end of a narrow 125 µm outer diameter optical fiber. Miniaturization is rendered possible by exploiting the concept of a leaky wave optical antenna for interfacing the scintillators and the fiber, and by taking advantage of the low propagation loss of narrow silica fibers and high detection yield of single-pixel photon counters. Upon irradiation at 6 MV, our fiber probe led to a linear detection response with a signal-to-noise ratio as high as 190 in air. Although implemented with inorganic scintillators and fiber, our fiber probe induces an intensity contrast in the impinging radiation lower than 0.9% over an area of 0.153 mm 2 . Our nano-optically driven approach opens the route for ultra-compact fiber dosimeters of negligible footprint in the radiotherapeutic processes, even with non-water equivalent fibers and scintillators. A large panel of therapies relying on ionizing radiations (photons or charged particles) may take benefit of this nano-optically-driven technology.

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“…Scintillator dosimeters are a relatively inexpensive dosimetry tool which are easy to fabricate. They have been applied to many clinical radiotherapy modalities, including external beam therapies, brachytherapy, and prostate cancer therapy …”

Section: Introductionmentioning

confidence: 99%

An algorithmic approach to single‐probe Cherenkov removal in pulsed x‐ray beams

Archer

Madden

et al. 2019

Medical Physics

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Purpose: The removal of Cherenkov light in an optical dosimetry system is an important process to ensure accurate dosimetry without compromising spatial resolution. Many solutions have been presented in the literature, each with advantages and disadvantages. We present a methodology to remove Cherenkov light from a scintillator fiber optic dosimeter in a pulsed megavoltage x-ray beam using the temporal waveform across the pulse. Methods: A sample waveform of Cherenkov light can be measured by exposing only the fiber to the beam. By assuming that the Cherenkov waveform closely matches the intensity of incident radiation, this waveform can be convoluted with the instantaneous scintillation response function to generate an expected scintillation signal. By finding the least-squares fit between these two functions and the experimental data, the estimated Cherenkov contribution can be subtracted off the net signal. This can be applied for arbitrarily complex Cherenkov waveforms (within the 2 ns timing resolution of the data acquisition), and in fact, the results suggest more fluctuations in the waveforms provide a better fit to data. Results: Four beam profiles for different field sizes and energies were found with this method. They closely matched references data measured with ionization chamber with average differences across the beam no more than 4%. Noisy waveforms are assumed to be the primary cause of differences between the analyzed scintillator and IC results. We propose methods for improving the results and optimizing the data acquisition and analysis processes. Conclusions: These results demonstrate that it is possible and effective with a single probe to use function fitting of expected data to experimental to remove a complicated Cherenkov signal from the net light signal in pulsed-beam optical dosimetry.

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X-ray microbeam measurements with a high resolution scintillator fibre-optic dosimeter

Cited by 20 publications

References 18 publications

High spatial resolution scintillator dosimetry of synchrotron microbeams

High spatial resolution scintillator dosimetry of synchrotron microbeams

Miniaturized fiber dosimeter of medical ionizing radiations on a narrow optical fiber

An algorithmic approach to single‐probe Cherenkov removal in pulsed x‐ray beams

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