Characterization of the exradin W1 plastic scintillation detector for small field applications in proton therapy

Hoehr, Cornelia; Lindsay, C.; Beaudry, Joel; Penner, Crystal; Strgar, V; Lee, R; Duzenli, Cheryl

doi:10.1088/1361-6560/aabd2d

Cited by 17 publications

(18 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The quenching correction parameter k B in table 1 for the BCF-12 scintillator deviates 10 % and 3 % from the results published in Wang et al (2012) and Alsanea et al (2018), respectively. The k B value for the BCF-60 scintillator is between the two values reported by Hoehr et al (2018). The Chou model in method (D) provided the best fit to the data for C 0 for the BCF scintillators, in agreement with Torrisi (2000), and C = 0 for the 81-0084 scintillator in agreement with Birks (1964).…”

Section: Scintillator Quenchingsupporting

confidence: 68%

“…(2.3). (C) By fitting the linear Birks model to the experimentally determined QCFs as a function of LET Φ for primaries and secondary protons in line with other studies (Wang et al, 2012;Hoehr et al, 2018). (D) By fitting the second-order Chou model to the QCFs as a function of LET Φ for primaries and secondary protons directly in eq.…”

Section: Comparison Of Quenching Modelsmentioning

confidence: 68%

See 1 more Smart Citation

Ionization quenching in scintillators used for dosimetry of mixed particle fields

et al. 2019

View full text Add to dashboard Cite

Ionization quenching in ion beam dosimetry is often related to the fluence-or dose-averaged linear energy transfer (LET). Both quantities are however averaged over a wide LET range and a mixed field of primary and secondary ions. We propose a novel method to correct the quenched luminescence in scintillators exposed to ion beams. The method uses the energy spectrum of the primaries and accounts for the varying quenched luminescence in heavy, secondary ion tracks through amorphous track structure theory. The new method is assessed against more traditional approaches by correcting the quenched luminescence response from the BCF-12, BCF-60, and 81-0084 plastic scintillators exposed to a 100 MeV pristine proton beam in order to compare the effects of the averaged LET quantities and the secondary ions. Calculations and measurements show that primary protons constitute more than 92 % of the energy deposition but account for more than 95 % of the luminescence signal in the scintilllators. The quenching corrected luminescence signal is in better agreement with the dose measurement when the secondary particles are taken into account. The Birks model provided the overall best quenching corrections, when the quenching corrected signal is adjusted for the number of free model parameters. The quenching parameter k B for the BCF-12 and BCF-60 scintillators is in agreement with literature values and was found to be k B = (10.6 ± 0.1) × 10 −2 µm keV −1 for the 81-0084 scintillator. Finally, a fluence threshold for the 100 MeV proton beam was calculated to be of the order of 10 10 cm −2 , corresponding to 110 Gy, above which the quenching increases non-linearly and the Birks model no longer is applicable.

show abstract

Section: Scintillator Quenchingsupporting

confidence: 68%

Section: Comparison Of Quenching Modelsmentioning

confidence: 68%

Ionization quenching in scintillators used for dosimetry of mixed particle fields

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Hence, several international organizations such as AAPM and IAEA suggested various dosimetry sensors when working under small fields. Some recent researches indicate that the suitable detectors for small field dosimetry are plastic scintillation‐based exradin W1, W2, and radiochromic films, owing to their good correction factor . However, the spatial resolution of these detectors is not yet up to the mark due to the minimum size of the sensor head requirement and radiochromic films suffer from time consuming techniques while being used.…”

Section: Introductionmentioning

confidence: 99%

High spatial resolution inorganic scintillator detector for high‐energy X‐ray beam at small field irradiation

et al. 2020

View full text Add to dashboard Cite

Purpose Small field dosimetry for radiotherapy is one of the major challenges due to the size of most dosimeters, for example, sufficient spatial resolution, accurate dose distribution and energy dependency of the detector. In this context, the purpose of this research is to develop a small size scintillating detector targeting small field dosimetry and compare its performance with other commercial detectors. Method An inorganic scintillator detector (ISD) of about 200 µm outer diameter was developed and tested through different small field dosimetric characterizations under high‐energy photons (6 and 15 MV) delivered by an Elekta Linear Accelerator (LINAC). Percentage depth dose (PDD) and beam profile measurements were compared using dosimeters from PTW namely, microdiamond and PinPoint three‐dimensional (PP3D) detector. A background fiber method has been considered to quantitate and eliminate the minimal Cerenkov effect from the total optical signal magnitude. Measurements were performed inside a water phantom under IAEA Technical Reports Series recommendations (IAEA TRS 381 and TRS 483). Results Small fields ranging from 3 × 3 cm2, down to 0.5 × 0.5 cm2 were sequentially measured using the ISD and commercial dosimeters, and a good agreement was obtained among all measurements. The result also shows that, scintillating detector has good repeatability and reproducibility of the output signal with maximum deviation of 0.26% and 0.5% respectively. The Full Width Half Maximum (FWHM) was measured 0.55 cm for the smallest available square size field of 0.5 × 0.5 cm2, where the discrepancy of 0.05 cm is due to the scattering effects inside the water and convolution effect between field and detector geometries. Percentage depth dose factor dependence variation with water depth exhibits nearly the same behavior for all tested detectors. The ISD allows to perform dose measurements at a very high accuracy from low (50 cGy/min) to high dose rates (800 cGy/min) and was found to be independent of dose rate variation. The detection system also showed an excellent linearity with dose; hence, calibration was easily achieved. Conclusions The developed detector can be used to accurately measure the delivered dose at small fields during the treatment of small volume tumors. The author's measurement shows that despite using a nonwater‐equivalent detector, the detector can be a powerful candidate for beam characterization and quality assurance in, for example, radiosurgery, Intensity‐Modulated Radiotherapy (IMRT), and brachytherapy. Our detector can provide real‐time dose measurement and good spatial resolution with immediate readout, simplicity, flexibility, and robustness.

show abstract

“…Since the linear energy transfer (LET) does change dramatically along the Bragg peak of proton therapy, the independence of both energy and dose rate are crucial characteristics in any new detector. Most scintillation detectors are known to exhibit increased quenching when LET increases 4,6,12–17 due to the participation of alternate modes of energy dissipation in regions of high ionization density. In order to resolve the Bragg peak of the proton dose depth profile, a fiber diameter of 250 m or less may be required 12 .…”

Section: Introductionmentioning

confidence: 99%

Novel Gd3+-doped silica-based optical fiber material for dosimetry in proton therapy

Hoehr

Morana

Duhamel

et al. 2019

Sci Rep

View full text Add to dashboard Cite

Optical fibers hold promise for accurate dosimetry in small field proton therapy due to their superior spatial resolution and the lack of significant Cerenkov contamination in proton beams. One known drawback for most scintillation detectors is signal quenching in areas of high linear energy transfer, as is the case in the Bragg peak region of a proton beam. In this study, we investigated the potential of innovative optical fiber bulk materials using the sol-gel technique for dosimetry in proton therapy. This type of glass is made of amorphous silica (SiO) and is doped with Gd ions and possesses very interesting light emission properties with a luminescence band around 314 nm when exposed to protons. The fibers were manufactured at the University of Lille and tested at the TRIUMF Proton Therapy facility with 8.2–62.9 MeV protons and 2–6 nA of extracted beam current. Dose-rate dependence and quenching were measured and compared to other silica-based fibers also made by sol-gel techniques and doped with Ce and Cu. The three fibers present strong luminescence in the UV (Gd) or visible (Cu,Ce) under irradiation, with the emission intensities related directly to the proton flux. In addition, the 0.5 mm diameter Gd-doped fiber shows superior resolution of the Bragg peak, indicating significantly reduced quenching in comparison to the Ce and Cu fibers with a Birks’ constant, k, of (0.0162 0.0003) cm/MeV in comparison to (0.0333 0.0006) cm/MeV and (0.0352 0.0003) cm/MeV, respectively. To our knowledge, this is the first report of such an interesting k for a silica-based optical fiber material, showing clearly that this fiber presents lower quenching than common plastic scintillators. This result demonstrates the high potential of this inorganic fiber material for proton therapy dosimetry.

show abstract

Characterization of the exradin W1 plastic scintillation detector for small field applications in proton therapy

Cited by 17 publications

References 46 publications

Ionization quenching in scintillators used for dosimetry of mixed particle fields

Ionization quenching in scintillators used for dosimetry of mixed particle fields

High spatial resolution inorganic scintillator detector for high‐energy X‐ray beam at small field irradiation

Novel Gd3+-doped silica-based optical fiber material for dosimetry in proton therapy

Contact Info

Product

Resources

About