On the nature of the light produced within PMMA optical light guides in scintillation fiber-optic dosimetry

Therriault‐Proulx, François; Beaulieu, Luc; Archambault, Louis; Beddar, Sam

doi:10.1088/0031-9155/58/7/2073

Cited by 92 publications

(85 citation statements)

References 24 publications

(81 reference statements)

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“…It must be noticed that this contribution is directly proportional to the irradiated fibre length and will be smaller for smaller irradiation fields. As reported by Therriault-Proulx et al, 8 the main source of stem effect at those energies is fibre fluorescence. Indeed,Čerenkov radiation is generated in PMMA by secondary electrons .178 keV.…”

Section: Precision Vs Beam Quality and Integration Timementioning

confidence: 51%

“…5 However, it is known that in addition to scintillating light emitted by the scintillator, a stem effect is produced in the fibre material and contributes to the detected signal. [6][7][8] When using megavoltage beams, the major component of this stem effect isČerenkov radiation. Multiple studies and solutions have been proposed in literature to remove thě Cerenkov light influence from the final signal.…”

Section: Introductionmentioning

confidence: 99%

“…[16][17][18][19] In addition, in the kilovoltage energy range, the stem effect is mainly due to the fluorescence of the optical fibre and its contribution has been reported to be small. 8 Its small influence on the final signal allows to simplify the dosemeter readout system.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of a scintillating fibre detector for small animal imaging and irradiation dosimetry

Deroff

Frelin-Labalme

Ledoux

2017

BJR

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Objective: Small animal image-guided irradiators have recently been developed to mimic the delivery techniques of clinical radiotherapy. A dosemeter adapted to millimetric beams of medium-energy X-rays is then required. This work presents the characterization of a dosemeter prototype for this particular application. Methods: A scintillating optical fibre dosemeter (called DosiRat) has been implemented to perform real-time dose measurements with the dedicated small animal X-RAD® 225Cx (Precision X-Ray, Inc., North Branford, CT) irradiator. Its sensitivity, stem effect, stability, linearity and measurement precision were determined in large field conditions for three different beam qualities, consistent with small animal irradiation and imaging parameters. Results: DosiRat demonstrates good sensitivity and stability; excellent air kerma and air kerma rate linearity; and a good repeatability for air kerma rates .1 mGy s 21. The stem effect was found to be negligible. DosiRat showed limited precision for low air kerma rate measurements (,1 mGy s 21 ), typically for imaging protocols. A positive energy dependence was found that can be accounted for by calibrating the dosemeter at the needed beam qualities. Conclusion: The dosimetric performances of DosiRat are very promising. Extensive studies of DosiRat energy dependence are still required. Further developments will allow to reduce the dosemeter size to ensure millimetric beams dosimetry and perform small animal in vivo dosimetry. Advances in knowledge: Among existing point dosemeters, very few are dedicated to both medium-energy X-rays and millimetric beams. Our work demonstrated that scintillating fibre dosemeters are suitable and promising tools for real-time dose measurements in the small animal field of interest.

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Section: Precision Vs Beam Quality and Integration Timementioning

confidence: 51%

Section: Introductionmentioning

confidence: 99%

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Characterization of a scintillating fibre detector for small animal imaging and irradiation dosimetry

Deroff

Frelin-Labalme

Ledoux

2017

BJR

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“…32 Therefore, only a single stem effect spectrum is required to account for the combined fluorescence and Cerenkov light. This spectrum (r Stem ) was acquired through irradiation of the clear optical fiber prior to the mPSD assembly using the HDR brachytherapy 192 Ir source.…”

Section: Iid Measuring the Dosementioning

confidence: 99%

On the use of a single‐fiber multipoint plastic scintillation detector for ¹⁹²Ir high‐dose‐rate brachytherapy

2013

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Purpose: The goal of this study was to prove the feasibility of using a single-fiber multipoint plastic scintillation detector (mPSD) as an in vivo verification tool during 192 Ir high-dose-rate brachytherapy treatments. Methods: A three-point detector was built and inserted inside a catheter-positioning template placed in a water phantom. A hyperspectral approach was implemented to discriminate the different optical signals composing the light output at the exit of the single collection optical fiber. The mPSD was tested with different source-to-detector positions, ranging from 1 to 5 cm radially and over 10.5 cm along the longitudinal axis of the detector, and with various integration times. Several strategies for improving the accuracy of the detector were investigated. The device's accuracy in detecting source position was also tested. Results: Good agreement with the expected doses was obtained for all of the scintillating elements, with average relative differences from the expected values of 3.4 ± 2.1%, 3.0 ± 0.7%, and 4.5 ± 1.0% for scintillating elements from the distal to the proximal. A dose threshold of 3 cGy improved the general accuracy of the detector. An integration time of 3 s offered a good trade-off between precision and temporal resolution. Finally, the mPSD measured the radioactive source positioning uncertainty to be no more than 0.32 ± 0.06 mm. The accuracy and precision of the detector were improved by a dose-weighted function combining the three measurement points and known details about the geometry of the detector construction. Conclusions: The use of a mPSD for high-dose-rate brachytherapy dosimetry is feasible. This detector shows great promise for development of in vivo applications for real-time verification of treatment delivery.

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“…It has been shown that by monitoring the light under two different wavelength filters, it is possible to isolate the luminescence signal from the Cherenkov signal. [79][80][81][82] As a consequence of the large amount of research into this area, it is now widely considered that the issue of the stem effect has been addressed and no longer poses a limitation in the sensors' potential for radiotherapy dosimetry.…”

mentioning

confidence: 99%

A review of recent advances in optical fibre sensors forin vivodosimetry during radiotherapy

O'Keeffe¹,

McCarthy²,

Woulfe³

et al. 2015

BJR

104

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This article presents an overview of the recent developments and requirements in radiotherapy dosimetry, with particular emphasis on the development of optical fibre dosemeters for radiotherapy applications, focusing particularly on in vivo applications. Optical fibres offer considerable advantages over conventional techniques for radiotherapy dosimetry, owing to their small size, immunity to electromagnetic interferences, and suitability for remote monitoring and multiplexing. The small dimensions of optical fibre-based dosemeters, together with being lightweight and flexible, mean that they are minimally invasive and thus particularly suited to in vivo dosimetry. This means that the sensor can be placed directly inside a patient, for example, for brachytherapy treatments, the optical fibres could be placed in the tumour itself or into nearby critical tissues requiring monitoring, via the same applicators or needles used for the treatment delivery thereby providing real-time dosimetric information. The article outlines the principal sensor design systems along with some of the main strengths and weaknesses associated with the development of these techniques. The successful demonstration of these sensors in a range of different clinical environments is also presented.

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On the nature of the light produced within PMMA optical light guides in scintillation fiber-optic dosimetry

Cited by 92 publications

References 24 publications

Characterization of a scintillating fibre detector for small animal imaging and irradiation dosimetry

Characterization of a scintillating fibre detector for small animal imaging and irradiation dosimetry

On the use of a single‐fiber multipoint plastic scintillation detector for ¹⁹²Ir high‐dose‐rate brachytherapy

A review of recent advances in optical fibre sensors forin vivodosimetry during radiotherapy

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On the nature of the light produced within PMMA optical light guides in scintillation fiber-optic dosimetry

Cited by 92 publications

References 24 publications

Characterization of a scintillating fibre detector for small animal imaging and irradiation dosimetry

Characterization of a scintillating fibre detector for small animal imaging and irradiation dosimetry

On the use of a single‐fiber multipoint plastic scintillation detector for 192Ir high‐dose‐rate brachytherapy

A review of recent advances in optical fibre sensors forin vivodosimetry during radiotherapy

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Product

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On the use of a single‐fiber multipoint plastic scintillation detector for ¹⁹²Ir high‐dose‐rate brachytherapy