Radiation-induced Luminescence Research Articles

Enhancing online dose distribution reconstruction in radiotherapy through sparse sampled rotating fiber arrays and deep learning

A optical fiber array dosimeter based on radiation-induced luminescence can be used in two-dimensional dose distribution measurements. However, using rotating fiber arrays introduces challenges in terms of online monitoring and variations in detector performance due to the long data acquisition time. This study aims to propose and demonstrate a novel method for online fast reconstruction of two-dimensional dose distributions in radiation therapy using projection data obtained from sparsely sampled rotating fiber arrays. The projection data were processed in both the projection and image domains to achieve restoration and noise reduction by deep learning techniques. The performance of the proposed method was evaluated using simulation data obtained by Monte Carlo toolkit Geant4 and experimental data obtained from a medical accelerator. Results showed that the method can successfully reconstruct dose distribution through sparse sampling and reduce the measurement time to one-sixth of the original. The peak signal-to-noise ratio, root mean square error, and structural similarity index were 23.72, 2.68, and 0.95, respectively. Additionally, the 3%/3 mm gamma pass rate reached 98.4% under specific irradiation conditions with a dose of at least 10% of the maximum dose. The integration of sparse sampling techniques, rotating fiber arrays, and deep learning techniques offers new possibilities for the fast and efficient reconstruction of two-dimensional dose distributions, ensuring high-quality radiotherapy outcomes.

Evaluation of Radiation-induced Luminescence Characteristics of Au Particles in CsCl Translucent Ceramic

Evaluation of Radiation-induced Luminescence Characteristics of Au Particles in CsCl Translucent Ceramic

Preirradiation Treatment Influence on the Radioluminescence of a Nitrogen‐Doped Optical Fiber Dosimeter

The dosimetry performances of a nitrogen‐doped core (diameter of 8 μm) optical fiber, before and after 100 kV X‐Ray preirradiation treatments, up to cumulated dose of 1 MGy(SiO2), to highlight their effects on the radiation‐induced luminescence (RIL), are investigated. The RIL reproducibility versus dose rate calibration curves (in the 0.17–50 Gy s−1 range) are evaluated using four sets of ten different probes: three sets using preirradiated samples at 80 kGy, 280 kGy, 1 MGy, respectively, and one set with pristine samples. The RIL kinetics during ≈60 h long preirradiations at constant dose rate are also studied, showing a non‐negligible bright burn effect. The main outcome is that the preirradiation improves the fiber dosimetry properties since it: 1) enhances fiber radiation detection sensitivity, 2) improves the linearity of the RIL dose rate dependence, and 3) suppresses the observed afterglow postirradiation effect. However, after preirradiation, larger dispersion between the different probes is noted, from 4% (non‐irradiated samples) to 10% for the 1 MGy preirradiated samples. The possible physical explanations are discussed on the basis of the preirradiation filling deep traps that, competing with the RIL centers for the trapping of electrons released by ionization, influence the RIL efficiency.

Radiation-induced luminescence properties of AEO-SiO2 (AE = Mg, Ca, Sr, Ba) glasses doped with Sn

Optical and scintillation properties of 50AEO-50SiO2-1SnO (AE = Mg, Ca, Sr, Ba) glasses were investigated. In photoluminescence (PL) and scintillation, the glasses showed a luminescence peak around 400 nm which was attributed to the T1-S0transitions of Sn2+. The afterglow levels of theAE = Mg and Ba glasses were better than that of a commercial Tl-doped CsI scintillator. The light yields of the glasses were quantitatively acquired and theAE = Ba glass showed the highest light yield of 63 ph/5.5 MeV-α of among the glasses.

Radiation-induced luminescence properties of BaCl2:Eu transparent ceramics fabricated by spark plasma sintering method

BaCl2:Eu transparent ceramics were synthesized by the spark plasma sintering method, and concentration dependence of Eu on optical and scintillation properties was investigated. BaCl2:Eu transparent ceramics showed photoluminescence (PL) and scintillation peaks at 400 nm due to 5d–4f transition of Eu2+. The PL and scintillation decay time constants of BaCl2:Eu transparent ceramics were ∼400 ns. The PL quantum yields (QYs) of 0.05, 0.1, 0.5, and 1% BaCl2:Eu transparent ceramics were 28.5, 25.6, 16.2, and 13.9%, respectively. The afterglow levels of BaCl2:Eu transparent ceramics were lower than CsI:Tl single crystal in practical use. The scintillation light yield of the 0.5% doped BaCl2:Eu transparent ceramic was 9800 photons/MeV when γ-rays by 137Cs were irradiated.

Radiation-induced luminescence and photoluminescence properties of (K,Rb)2CuBr3 crystals synthesized by the slow cooling method

(K,Rb)2CuBr3 crystals were fabricated by the slow cooling method, and their photoluminescence (PL) and scintillation properties were examined. Emission bands were observed at 350–550 nm under UV and X-ray irradiation. PL quantum yields of K2CuBr3, (K0.25,Rb0.75)2CuBr3, (K0.5,Rb0.5)2CuBr3, (K0.75,Rb0.25)2CuBr3, and Rb2CuBr3 were respectively 75.8, 71.0, 82.3, 96.9, and 96.3%. The scintillation decay curves were approximated by a sum of three exponential functions, and the decay time constants due to recombination of self-trapped excitons were 58–63 μs. The afterglow levels of the K and Rb-mixed samples at 20 ms passed after X-ray irradiation decreased to 10–40 ppm, compared with those of K2CuBr3 and Rb2CuBr3. Among these samples, (K0.75, Rb0.25)2CuBr3 showed the highest light yield of 7400 ph/MeV among the samples calculated from the pulse height spectra of 137Cs γ-rays (662 keV).

Proton Dosimetry Using Radiation-Induced Luminescence in Micrometer-Core Germanosilicate Optical Fibers

We investigated the radiation-induced luminescence of 62.5 μm, 10 μm and 3 μm germanosilicate single- and multi-mode telecom-grade optical fibers for use as high-resolution dosimeters at dose rates ranging between 5 Gy s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and 120 Gy s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> using proton beams of varying currents and energies. Only one of the two single-mode fibers under investigation had a detectable light yield, with a dose rate threshold around 20 Gy s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . All tested multi-mode fibers showed a detectable response over the whole accessible dose rate range. All tested multi-mode fibers displayed a linear dose rate response when the proton beam energy was fixed. However, the slope of the response curve showed a strong dependence on the proton beam energy. Geometry and material differences, as well as radiation-induced attenuation effects have been ruled out as sources for the observed proton energy dependence of the dose rate response.

Radiation-induced Luminescence Properties of Ce-doped ZnBr2-based Glasses

Radiation-induced Luminescence Properties of Ce-doped ZnBr2-based Glasses

Radiation-induced Luminescence Properties of Ce-doped SrAl2O4 Crystal and Translucent Ceramic

Radiation-induced Luminescence Properties of Ce-doped SrAl2O4 Crystal and Translucent Ceramic

Radiation-induced Luminescence Properties of Tm-doped Bi4Ge3O12 Single Crystals

Radiation-induced Luminescence Properties of Tm-doped Bi4Ge3O12 Single Crystals

Radiophotoluminescence Phenomenon of CaF2 Ceramics Doped with Li

The objective of this study is to examine the impact of Li-doping on the radiophotoluminescent (RPL) properties of CaF2. Before ionizing irradiation, Li-doped CaF2 exhibited no photoluminescence (PL) under excitation in the range of 250–700 nm. After ionizing irradiation, Li-doped CaF2 displayed PL at 800 nm when excited at 390 and 610 nm. The decay time constant for this luminescence was determined to be 20 ns, which suggests that it is attributed to (F2+)A centers. All the Li-doped CaF2 showed higher PL intensity than the non-doped CaF2 did, with the highest intensity observed in the 0.5% Li-doped CaF2. The 0.5% Li-doped CaF2 was also found to have a minimum measurable dose of 14 μGy as an RPL dosimeter, and the RPL response monotonically increased to 10 Gy. As for radiation-induced luminescence other than RPL, the scintillation peak and the thermally stimulated luminescence (TSL) glow peak were mainly observed at 300 nm and 140 °C, respectively.

Recent Advances in Radiation-Induced Luminescence Materials

Recent Advances in Radiation-Induced Luminescence Materials

Properties of Gd-Doped Sol-Gel Silica Glass Radioluminescence under Electron Beams

The radiation-induced emission (RIE) of Gd3+-doped sol-gel silica glass has been shown to have suitable properties for use in the dosimetry of beams of ionizing radiation in applications such as radiotherapy. Linear electron accelerators are commonly used as clinical radiotherapy beams, and in this paper, the RIE properties were investigated under electron irradiation. A monochromator setup was used to investigate the light properties in selected narrow wavelength regions, and a spectrometer setup was used to measure the optical emission spectra in various test configurations. The RIE output as a function of depth in acrylic was measured and compared with a reference dosimeter system for various electron energies, since the dose-depth measuring abilities of dosimeters in radiotherapy is of key interest. The intensity of the main radiation-induced luminescence (RIL) of the Gd3+-ions at 314 nm was found to well represent the dose as a function of depth, and was possible to separate from the Cherenkov light that was also induced in the measurement setup. After an initial suppression of the luminescence following the electron bunch, which is ascribed to a transient radiation-induced attenuation from self-trapped excitons (STEX), the 314 nm component was found to have a decay time of approximately 1.3 ms. An additional luminescence was also observed in the region 400 nm to 600 nm originating from the decay of the STEX centers, likely exhibiting an increasing luminescence with a dose history in the tested sample.

Radiation-induced luminescence in oxide glasses

Radiation-induced luminescence, and scintillation in particular, in glass is difficult to control, and its efficiency is hard to improve owing to the structural diversity of glasses. However, the structural and chemical compositional diversity and excellent formability of glass have remained attractive for phosphor applications. This paper summarizes recent studies on glass-based scintillators. Based on the general relationships between scintillation and photoluminescence quantum efficiency in materials, the prospects of glass-based scintillators are discussed.

Radiation-induced luminescence properties of Sn-doped hafnium aluminosilicate glass ceramics prepared by using a xenon image furnace

In this study, Sn-doped 10HfO2–10Al2O3–80SiO2 glasses were prepared using a xenon imaging furnace and their physical, optical, and scintillation properties were investigated. At the composition ratio, the specimens did not completely vitrify, and they were crystallized glasses that contained nanocrystals of c-HfO2. Raman spectra show the absorption bands due to Si–O–Hf bonds, and the band clearly indicated an effective molecular mingling of SiO2 and HfO2 components in the glass. Moreover, the energy dispersive X-ray spectroscopy maps suggested that the elemental distribution of this glass specimen is heterogeneous. In terms of optical properties of the glass, all the specimens showed emission due to Sn2+, and their tendency to increase photoluminescence quantum yield with increasing Sn concentration. The estimated luminescence from pulse height spectrum measurements under alpha irradiation was ∼2500 ph MeV−1, approximately 35% of the GS-20 glass scintillator counterpart.

Optical fibre array detector to monitor irradiations for medical radioisotope production

Low-energy cyclotrons are in use worldwide to produce medical radioisotopes for nuclear medicine. Beam monitoring during the irradiation of targets is difficult due to the high-power density of low-energy protons, space limitations, and interference with beam delivery. Doped silica fibres are sensitive to prompt ionizing radiation from the bombarded target, and produce radiation induced luminescence (RIL) when exposed. The fibres can be attached to the outside of the target in a low-profile fibre array, ensuring efficient and safe operation. Here, we present the results from our prototype of such a fibre array. It consists of four Ce-doped fibres with a diameter of 200 μm and has been installed at the TR13 medical cyclotron at TRIUMF where it has been tested at different irradiation conditions.

PHSOR11 Presentation Time: 1:20 PM: Verify the Transit Time Correction Accuracy of the Bravos Afterloader System Using a Novel Scintillation-Based Brachytherapy Quality Assurance Device

<h3>Purpose</h3> Compared to the older generations, the new Bravos high dose rate (HDR) afterloader offers the function to automatically correct dwell time to compensate the transit dose effect. To our best knowledge, there is no QA attempt to verify the accuracy of this correction. To address this issue, a new transit time measurement module has been developed and included in the OriQA HDR QA device, an autonomous phantom for HDR brachytherapy quality assurance. In this work, we employ the OriQA system to verify the transit time correction accuracy of the Bravos afterloader system. <h3>Method</h3> The OriQA device utilizes radioluminescence imaging technique to accurately measure HDR source strength, dwell time, and dwell position. It consists of a 20 cm needle applicator insert, a radioluminescence phosphor sheet placed directly atop the applicator, a digital camera, and software for signal processing and displaying results. Radiation-induced luminescence photons are emitted from the phosphor sheet and captured by the camera. The signal intensity and location are processed to yield relative source strength and dwell information. For the verification test, one of the Bravos channels was connected to the OriQA applicator using a one-meter transfer tube. After specific plan delivery, the raw data of OriQA measurement including source position and time was exported to Matlab for further analysis. The real dwell time at each dwell position and the transit time between dwells during cable extension and retraction were extracted. The transit time correction method provided by the vendor was applied to the measurement, yielding the delivered dwell time. The percentage difference between the delivered and planned dwell time was calculated and used as an indicator of the transit time correction accuracy. Several verification plans were created including seven with fixed dwell steps, one with variable dwell steps, and one with variable dwell time. Plans with fixed dwell steps were delivered three times. The rest were delivered once. Plan details are listed in table 1. For each plan, the mean and standard deviation of the difference between planned and delivered dwell time were calculated from all dwell positions and deliveries. <h3>Results</h3> The deviations between the planned and delivered dwell time are listed in table 1. For plans with less than 4 cm dwell step, the accuracy of transit time correction is, on average, less than 1.2% of the dwell time. For plans with 4 cm and 9 cm dwell step, the accuracy is 1.5% and 2.85%, on average, respectively. Dwell time variation does not affect the correction accuracy, as shown in plan 9. Standard deviations of plan 3, 4, and 9 are greater than 1% due to the relatively large difference at the proximal dwell. <h3>Conclusion</h3> This is the first study that successfully verifies the transit time correction accuracy of the Bravos system. Less than 2% accuracy is observed for clinically relevant dwell steps (0.3 cm to 4 cm). Variations in dwell step, dwell position, and dwell time do not worsen the accuracy.

Evaluation of radiation-induced luminescence properties of Tb-doped LiCaPO4

We have investigated photoluminescence (PL), scintillation, and dosimetric properties of the undoped and Tb-doped LiCaPO4 samples. The luminescence origin of the undoped and Tb-doped samples were ascribed to the self-trapped exciton (STE) and 4f-4f transitions of the Tb3+, respectively. In Thermally stimulated luminescence (TSL) glow curves, undoped samples showed main peak at 220 °C, and Tb-doped samples showed main peak at 130 °C. The Tb-doped samples demonstrated the more than 50 times higher TSL intensity than that of undoped one. In addition, the lowest measurable dose (LMD) of the Tb-doped samples were estimated to exceed 1 μGy.

Recent Advances in Optical Fiber Enabled Radiation Sensors.

Optical fibers are being widely utilized as radiation sensors and dosimeters. Benefiting from the rapidly growing optical fiber manufacturing and material engineering, advanced optical fibers have evolved significantly by using functional structures and materials, promoting their detection accuracy and usage scenarios as radiation sensors. This paper summarizes the current development of optical fiber-based radiation sensors. The sensing principles of both extrinsic and intrinsic optical fiber radiation sensors, including radiation-induced attenuation (RIA), radiation-induced luminescence (RIL), and fiber grating wavelength shifting (RI-GWS), were analyzed. The relevant advanced fiber materials and structures, including silica glass, doped silica glasses, polymers, fluorescent and scintillator materials, were also categorized and summarized based on their characteristics. The fabrication methods of intrinsic all-fiber radiation sensors were introduced, as well. Moreover, the applicable scenarios from medical dosimetry to industrial environmental monitoring were discussed. In the end, both challenges and perspectives of fiber-based radiation sensors and fiber-shaped radiation dosimeters were presented.

Correlation between luminescence of cerium and chemical compositions in lithium silicate-based glasses

In contrast to conventional photoluminescence, the radiation-induced luminescence of glasses is difficult to understand because of the complex energy transfer system. In this study, we examined the optical and luminescent properties of Ce 3+ in lithium silicate-based glasses prepared in air. The Ce 3+ ratio in the glasses decreased with increasing Ce concentration, which is the opposite of the trend previously observed for Al 2 O 3 –P 2 O 5 glasses. The 33.3Li 2 O-66.7SiO 2 (LS) glass, which is the stoichiometric chemical composition of Li 2 Si 2 O 5 crystal, exhibited higher photoluminescence intensity, quantum yield (QY), X-ray-induced scintillation intensity, and storage luminescence than 34Li 2 O–5MgO–10Al 2 O 3 –51SiO 2 (GS10) glass. The pulse height spectra obtained by 252 Cf irradiation also suggested that a higher light yield was observed in the LS glasses compared with GS10 glasses. The 0.5 mol% Ce-doped LS glass exhibited the highest light yield 493.7 ph/n among these glasses despite the low QY value. It is found that additional factors correlate with the light yield by 252 Cf irradiation in addition to the QY and Ce 3+ concentrations. • We have prepared Ce 3+ in lithium silicate-based glasses containing different Ce concentrations. • The quantum yield (QY) depends on both the chemical composition and the Ce 3+ ratio. • 33.3Li 2 O-66.7SiO 2 (LS) glass exhibited photoluminescence intensity and quantum yield higher than MgO–Al 2 O 3 substituted glass. • The 0.5 mol% Ce-doped LS glass exhibited the highest light yield 493.7 ph/n despite the low QY value.