Dosimetry Applications Research Articles

A primary simulation study of scintillating fibre dosimetry for a proton minibeam

In this paper is explored the application of optical fibre-based dosimetry in the context of charged-particles MiniBeam Radiation Therapy through comprehensive simulation analyses. A FLUKA simulation of 64 Scintillating Plastic Optical Fibre array was implemented based on a prototype built in our group. The simulations indicate that the proposed system accurately reproduces the peak-and-valley pattern of minibeams. The optical photons transport inside and between fibres was also simulated, revealing that the optical crosstalk is negligible. The resilience of the detector’s electronics under secondary radiation composed of photons and neutrons was assessed. Our results suggest the electronics’ ability to withstand the expected radiation environment in clinical accelerators. This simulation-based investigation provides valuable insights into the feasibility of optical fibre-based dosimetry for MBRT. The results show the potential of using an array of thin scintillating plastic optical fibres to determine the peak–valley dose ratio, which is a key parameter to assess the efficacy of this emerging modality.

TL, EPR, and optical properties of undoped and Eu-, Ce-, Tb-, Sm-, Cu-, Mn-, and Li- doped MgSiO3 phosphors, synthesized by sol-gel combustion technique

Polycrystalline MgSiO3 samples, undoped or doped with rare earth- (Eu, Tb, Ce, Li, Sm), transition- (Mn and Cu), and alkali metal- (Li) elements, were prepared by the sol-gel combustion method and characterized by thermoluminescence, electron spin resonance, and optical properties. Enstatite and protoenstatite phases are observed in undoped and doped MgSiO3. Better TL results have been observed for phosphors doped with Tb, Ce, and Li (0.5 % mol). Fading experiments and the GCD method have been performed. EPR signals of gamma-irradiated phosphors indicate the formation of radiation-induced defect centers. Cu-doped MgSiO3 shows an unusual feature of the Cu2+ ion. The Cu2+ ion occupies a tetragonally compressed octahedral site, presenting an unconventional attribute. Optical bandgap value Eg is higher for the Ce, Tb, Mn, Li, Sm, and Cu-doped MgSiO3 phosphors. Ce, Li, and Tb dopant ions were found suitable for the MgSiO3 sample regarding its thermoluminescent response and its possible application in radiation dosimetry.

Exploring the thermoluminescence characteristics of smartphone screen safety glasses for retrospective dosimetry applications

In clinical settings, standard dosimeters might miss radiation mishaps. Retrospective dosimeters could help to track personnel (such as patients and other staff who don't wear dosimeters) exceeding safe limits and assess long-term exposure trends. This study has investigated key thermoluminescence (TL) dosimetric characteristics, including the glow curve structure, dose-response, energy dependence, sensitivity and fading of various safety glasses that are used as screen protectors of smartphones subjected to photon irradiation. Among the studied glasses, the HD Anti-Peep safety glass for iPhone has been found to exhibit a linear dose-response with a regression coefficient of 99% within the dose range of 2–10 Gy. Moreover, all the safety glasses showed independence with respect to photon energy of 6 MV and 10 MV. The TL glow curves of the samples showed a broad glow peak between 125 °C and 325 °C at 10 Gy. The TL kinetic parameters of the safety glasses were also studied by analyzing the glow curves using the peak shape and initial rise method. The geometric factor (μg) is found to be within the range of 0.43–0.53, which indicates the suitability of applying Chen's general-order formula to calculate the kinetic parameters such as activation energy, frequency factor and trap lifetime. The activation energy (E) and frequency factor (s) are found in the range of 0.31–0.54 eV and 4.55 × 103 to 2.12 × 106 s−1 respectively obtained via the peak shape method. The relatively long trap lifetime and observed thermoluminescence features indicate that the HD Anti-Peep safety glass offers a better option to estimate dose retrospectively to ensure the safety of human health.

Luminescence and dosimetry investigations of Eu(III) doped Ca2CeVO6 novel double perovskite

A novel composition of vanadate double perovskite Ca2CeVO6 doped with Eu3+ was successfully synthesized using combustion synthesis, wherein the doping levels of Eu3+ ranged from 1 to 6 mol%. The Rietveld refinement of the powder X-ray diffraction (XRD) data confirmed the orthorhombic structure of the phosphors. Scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDAX) were employed to investigate the surface morphology and elemental distribution in the phosphor, respectively. Under the excitation at 280 nm and 467 nm, the phosphor exhibited strong down-conversion red photoluminescence (PL) emission, attributed to Eu3+ transitions (5D0-7FJ, where J = 0–3) originating from its 4f states. The intensity of PL emission shows increasing trend with increasing doping concentration. However, exceeding the threshold doping concentrations led reduction in PL intensity due to multipolar interaction effects. Additionally, the Eu3+ doped Ca2CeVO6 phosphors were subjected to irradiation with a radioactive 90Sr/90Y beta source to explore their thermoluminescence (TL) properties. Post-irradiation, the phosphors displayed prominent TL glow curves, with the most intense peak at around 94 °C, followed by peaks at 160 °C and 288 °C. The TL intensity of these peaks exhibited a linear dose response within the dose range of 1 Gy–50 Gy. Besides, the TL fading and reproducibility tests showed satisfactory results. Furthermore, Tmax-Tstop experiments revealed the presence of three trap centres within the trap depth range of 0.7–2.1 eV in the Ca2CeVO6:Eu3+ phosphor. Additionally, the glow curve deconvolution (GCD) was employed to determine trapping parameters, providing valuable insights into the TL behaviour of the phosphor. Overall, the results suggest that the novel phosphor under study holds promise for its applications in lighting devices and TL dosimetry (TLD).

SrAl2O4: Ce: Synthesis and dosimetric characteristics of a new highly sensitive TL phosphor for dosimetry

Strontium aluminate (SrAl2O4) doped with different Ce concentrations was synthesized by the solid-state reaction method to find the best thermoluminescent response. The crystal structure of the material has been analyzed by Rietveld refinement of X-ray diffraction (XRD) results. The effects of different dopant concentrations and thermal annealing regimes on TL sensitivity and the optimum conditions for producing dosimeters with superior sensitivity to commercial dosimeters were investigated. It has been shown that the maximum TL sensitivity is obtained at a concentration of 0.3 mol% Ce and a heat treatment at 1000 °C for 2 h. The TL glow curve of Ce-doped strontium aluminate (SrAl2O4) pellets shows three TL peaks at 90, 150, and 250 °C. The dosimetric characteristics of the new material examined in this work are linear response in the dose range with applications in personal and environmental dosimetry; TL sensitivity; minimum detection dose; reproducibility; energy dependence; and TL signal fading. Based on the results obtained, the synthesized material is a dosimeter with a sensitivity 2.44 times higher than the commercial dosimeter TLD-100 (LiF:Ti,Mg).

Characterization of a thermally stable red-light-emitting phosphor: synthesis, photoluminescence, and thermoluminescence studies of CsCaF3 compound doped with Eu3+ for solid-state lighting applications

In this investigation, we focused on the synthesis and characterization of CsCaF3 compound doped with europium (Eu3+) ions using a solid-state route. To analyze the crystal structure of the synthesized phosphors, X-ray diffraction analysis was employed. Additionally, the doped sample underwent examination of surface morphology and elemental composition through Field Emission Scanning Electron Microscopy and EDAX mapping. The color of the pure and doped CsCaF3 sample was quantified and fitted using Color coordinate graph by the Commission Internationale de l'Eclairage (CIE). The red emission on the doped CsCaF3 compound was detected at 465 nm, which is the transition from 5D0 to 7Fj (j = 0, 1, 2, and 3). The 0.5 mol. % Eu3+ doped CsCaF3 sample was found to have a color purity of 81% and an associated color temperature of 1660 K, indicating its suitability for aesthetic lighting applications. Furthermore, thermoluminescence study, electron paramagnetic resonance (EPR), and effective atomic number (Z eff) calculations were conducted to provide valuable information for potential radiation dosimetry applications.

Investigating luminescence signals of pharmaceuticals and dietary supplements for emergency dosimetry

This study investigates the potential use of dietary supplements and pharmaceuticals containing magnesium, calcium or potassium for emergency dosimetry applications using the phenomenon of optically stimulated luminescence (OSL). Signal measurements were carried out using different stimulation wavelengths, and blue light stimulation was found to be the most efficient. More than half of the samples exhibited a measurable OSL signal and relatively high radiation sensitivity compared to other previously measured emergency detectors. Moreover, samples generally demonstrated a linear dose response. Possible causes of their high zero-dose signal were investigated: mechanical processing and UV light excitation. As variability in sensitivity was observed, the test-dose protocol was used during measurements. Furthermore, the study showed a significant loss of OSL signal intensity within 24 h after irradiation, which suggests the necessity for a fading correction. Finally, a dose recovery test was performed to evaluate the materials and the test-dose protocol under realistic conditions. The findings indicate the potential for using pharmaceuticals and dietary supplements in the event of a radiation emergency due to their dosimetric properties and ease of obtaining.

Hematological and neurological impact studies on the exposure to naturally occurring radioactive materials

Naturally Occurring Radioactive Materials (NORM) contribute to everyone's natural background radiation dose. The technologically advanced activities of the gas and oil sectors produce considerable amounts of radioactive materials as industrial by-products or waste products. The goal of the current study is to estimate the danger of long-term liability to Technologically Enhanced Naturally Occurring Radioactive Materials (TE-NORM) on blood indices, neurotransmitters, oxidative stress markers, and β-amyloid in the cerebral cortex of rats' brains. Twenty adult male albino rats were divided into two equal groups (n = 10): control and irradiated. Irradiated rats were exposed to a total dose of 0.016 Gy of TE-NORM as a whole-body chronic exposure over a period of two months. It should be ''The results showed no significant changes in RBC count, Hb concentration, hematocrit percentage (HCT%), and Mean Corpuscular Hemoglobin Concentration (MCHC). However, there was a significant increase in the Mean Corpuscular Volume of RBCs (MCV) and a significant decrease in cell distribution width (RDW%) compared to the control. Alteration in neurotransmitters is noticeable by a significant increase in glutamic acid and significant decreases in serotonin and dopamine. Increased lipid peroxidation, decreased glutathione content, superoxide dismutase, catalase, and glutathione peroxidase activities indicating oxidative stress were accompanied by increased β-amyloid in the cerebral cortex of rats' brains. The findings of the present study showed that chronic radiation liability has some harmful effects, that may predict the risks of future health problems in occupational radiation exposure in the oil industries. Therefore, the control of exposure and application of sample dosimetry is recommended for health and safety.

Beta-irradiated ZnGa2O4:Sm3+ phosphor: Thermoluminescence glow curves and kinetic parameters via gel combustion synthesis

This study examines the X-ray Diffraction (XRD) characteristics of Sm3+-doped ZnGa2O4 phosphor, shedding light on its structural characteristics. The XRD data reveal distinctive peaks that represent the crystal's lattice structure. This provides the basis for a more detailed analysis of thermoluminescence (TL). Initially, the TL glow curves corresponding to different concentrations of Sm were analysed, leading to the identification of the most favorable Sm concentration. Subsequently, an investigation was conducted into the TL behavior of the material in response to varying doses within a broad spectrum of beta radiation, revealing a linear characteristic (b=1.075) across doses ranging from 0.1 Gy to 50 Gy. Following this, a reusability assessment was executed over three measurement sets, wherein it was ascertained that the deviation in peak area across ten cycles did not surpass 2 %. Furthermore, it was investigated how different heating rates ranging from 0.5 °C/s to 7 °C/s affect the TL curve of the material. To determine the TL trap parameters of the sample, Initial Rise (IR) and Computerized Glow Curve Deconvolution (CGCD) methods were employed. A consistent pattern of activation energy values was observed in both IR in the TM-Tstop experiment and CGCD analyses, indicating a uniform response to distinct energy levels within the sample. In terms of providing valuable insights into the characteristics of TL, these methods were found to be very effective. This contributed to a comprehensive understanding of charge carrier dynamics within the crystal lattice. Moreover, Peaks I, II, and III showed a linear response to applied doses, indicating the material's potential for dosimetry applications. The findings of this study not only provide insights into Sm3+-doped ZnGd2O4 phosphors' TL properties, but also enhance our understanding of how to optimize their radiation response.

Unveiling highly sensitive Dy3+ doped BaMgAl10O17 phosphor’s thermoluminescence trap features and temperature dependent luminescence for solid state lighting applications

This article explores the structural, morphological, thermoluminescence, and temperature-dependent emission properties of novel Dy3+ doped BaMgAl10O17(BAM-Dy) phosphors. Structural studies reveal that the phosphor has a similar structure to β-alumina. Rod-shaped interlinked surface morphology is a notable characteristic of the BAM-Dy samples. Incorporation of Dy3+ ions lead to the formation of distinct emission peaks (485 nm, 577 nm, and 635 nm) in the PL emission spectra. The effect of dopant concentration on the light output is crucial, and the highest PL intensity is observed for 1.5 mol% of Dy3+ concentration. The potential use of BAM-Dy phosphors for Gamma radiation detection and measurement is tested through thermoluminescence studies, which reveal high sensitivity, low threshold dose values, and exceptional response to low gamma doses, making them suitable for dosimetry applications. The investigation of trap parameters provides useful information about the number of traps, trapping mechanism, and trap energies, which is essential for in-depth study of synthesized phosphors for γ dosimetry application. The study of the effect of temperature on the luminescence behaviour is crucial for the application of phosphors in the light-emitting field. The BAM-Dy samples exhibit excellent thermal stability even at 210 °C, making them suitable for use in the field of White LEDs.

Synthesis and thermoluminescence study of Dy3+ doped ZnAl2O4 phosphor for high-dose dosimetry application

Synthesis and thermoluminescence study of Dy3+ doped ZnAl2O4 phosphor for high-dose dosimetry application

Enhanced internal dosimetry for alimentary tract organs in nuclear medicine based on the ICRP mesh-type reference phantoms

This study introduces a refined approach for more accurately estimating radiation doses to alimentary tract organs in nuclear medicine, by utilizing the ICRP pediatric and adult mesh-type reference computational phantoms (MRCPs) that improved the anatomical representation of these organs. Our initial step involved compiling a comprehensive dataset of electron Specific Absorbed Fractions (SAFs) for all source-target pairs of alimentary tract organs in both adult and pediatric phantoms, calculating SAFs for all cases in the present study only except those computed in the previous study for certain pediatric phantom cases. Subsequently, we determined S values for 1252 radionuclides, facilitating dosimetry applications. The consistency of target and source masses for alimentary tract organs in the MRCPs with the reference values in ICRP Publication 89 led to noticeable differences in SAF, S values, and consequently, absorbed dose coefficients when compared to the stylized models in ICRP Publication 100. Notably, the S value ratios (MRCP/stylized) for selected radionuclides—11C, 18F, 68Ga, and 131I—ranged from 0.41 to 7.60. Particularly for therapeutic 131I-iodide in thyroid cancer, the use of MRCPs resulted in up to 1.49 times higher absorbed dose coefficients for the colon than those derived from stylized models, while the stomach dose coefficients decreased by a factor of 0.72. The application of our findings promises enhanced, more realistic dosimetry for alimentary tract organs, especially beneficial for radiopharmaceuticals likely to accumulate within these organs.

Investigation of structural and TL kinetic parameters of smartphone screen protector glasses for applications in retrospective dosimetry

The study evaluated the structural and thermoluminescence (TL) kinetic parameters of smartphone screen protector glasses in order to use them for post-accident dose reconstruction from unplanned nuclear events. The fact that most individuals use mobile phones in working environments including nuclear power plant sites, served as the impetus for the study. The TL glow curves indicate the physical properties of the defects involved in the luminescence process; therefore, they have been analyzed to study the TL kinetic parameters by employing peak shape, initial rise and glow curve deconvolution method within the dose ranges from 2 to 50 Gy. The geometric factor (μg) ranges between 0.46 and 0.56, suggesting that Chen's general-order method can be used to compute the kinetic parameters, including activation energy (E), frequency factor (s) and trap lifetime (τ). The examined trapping parameters (E = 0.33–0.57 eV, s = 5.22E+03–8.65E+06 s−1 for peak shape and E = 0.36–0.96 eV, s = 2.90E+04–1.88E+11 s−1 for initial rise methods) suggest promise for TL dosimetry applications. Additionally, the observed lifetime (τ = 4.88E+5 s) implies the feasibility of dose reconstruction even several days after an accident, making it suitable for retrospective dosimetry. Micro-Raman spectroscopy revealed a clear correlation between increasing gamma radiation dose and microstructural damage. The analysis of intensity ratio (ID/ISi) for other components to silica, along with the area of deconvoluted micro-Raman spectra in high-frequency regions, indicated dose-dependent structural modifications and internal defect annealing. Further confirmation of structural alterations within the studied dose range was obtained through the analysis of crystallite size (Lc), dislocation density (δ), lattice strain (ɛ) and FWHM (Full Width at Half Maximum) from XRD (X-ray diffraction) patterns. These findings collectively suggest the potential of smartphone screen protector glass as a viable material for emergency dosimetry applications.

Radiochromic film EBT3 calibration for linear accelerator in 10 MV

Radiochromic film is used to applications in dosimetry have become increasingly significant for studies on radiotherapy. Due to sensitivity to exposure to ionizing radiation, radiochromic films are commonly used to obtain dose distribution maps and for calibration curves. The calibration curves in the radiochromic films can be use radiochromic films as a dosimetry method and then seek the generation of images with lower dose deposition and higher diagnostic quality. When ionizing radiation interacts with matter it generates energy deposition. Radiation dosimetry is important for medical applications of ionizing radiation due to the increasing demand for diagnostic radiology and radiotherapy. The film is a dose measurement method that records the energy deposition by the darkening of its emulsion. Radiochromic films have a little visible light sensitivity and respond better to ionizing radiation exposure. The aim of this study is to obtain the resulting calibration curve by the irradiation of radiochromic film strips, making it possible to relate the darkening of the film with the absorbed dose, to measure doses in experiments with X-ray beam of 10 MeV in Linear Accelerator. The objective of this study is to obtain the calibration curves of the radiographic film for exposure with X-ray beam in Linear Accelerator scanner for realize measures of typical doses found in radiotherapy. It was used Gafchromic EBT Radiochromic Film, which shows little sensitivity to visible light and a response in the range of 0.1 to 10 Gy for X-ray beam. In the experiments, a Solid Water Phantom, with a 30x30x2.0 cm³. The strips were scanned and processed using the ImageJ software to obtain the intensity values resulting from the absorbed radiation by grayscale. The darkening responses on film strips according to the doses were observed and they allowed obtaining the corresponding numeric values to the darkening for each specific dose value. From the numerical values of darkening, a calibration curve was obtained.

Development of CaSO4:RE,Li (RE = Tm, Eu, Tb) composites for thermally or optically stimulated luminescence dosimetry

This work proposed the development of CaSO4:Tm,Li, CaSO4:Tb,Li and CaSO4:Eu,Li composites for application in radiation dosimetry, using luminescent techniques such as thermoluminescence (TL) and optically stimulated luminescence (OSL). The CaSO4 crystals were produced by the adapted slow evaporation route and characterized using X-ray diffraction (XRD), TL and OSL techniques. XRD analyses showed that the doped CaSO4 samples presented a single phase. The CaSO4:Eu,Li composites showed TL signals with peaks around 145 °C and 180 °C. The CaSO4:Tb,Li and CaSO4:Tm,Li composites showed TL signals with peaks centered at 165 °C and 275 °C. For the CaSO4:Tb and CaSO4:Tm samples, the addition of lithium as co-dopant resulted into a significant increase (2x) in the total TL signal of the samples. The CaSO4:Tm,Li samples presented a very intense OSL signal, about 80x greater than the signal of the other samples produced. This allows the applicability of TL/OSL detectors even more sensitives. The TL emission spectra of the samples showed typical emissions of Eu2+ ions (280 nm), Eu3+ (614 nm), Tb3+ (544 nm) and Tm3+ (455 nm). No emission corresponding to lithium was identified. All the samples produced showed linearity in the dose range used and good reproducibility, with variations below 10%. The CaSO4:Tm,Li samples showed the lowest limit of detection and fading. The evaluated dosimetric characteristics denote that these developed composites have potential application as TL/OSL detectors.

A cone-beam optical CT based on a convergent light source – Characterization and optimization

PurposeEmploying a Fresnel lens and a point-like light source to create a convergent light beam for the camera effectively minimizes stray light and enhances image quality in optical computed tomography (OCT), benefiting 3D dosimetry applications. This study outlines the development of an economical cone-beam optical computed scanner for 3D dosimetry. MethodsOptical performance was assessed by calculating modulation transfer function (MTF) with pattern charts. Stray light was evaluated by imaging a cylinder flask and a square grid with 5 mm diameter holes to determine the stray-to-primary ratio. Reconstruction quality was determined using SIRT-TV and compared with spectrophotometry attenuation coefficients, with the best regularization parameter (λ = 0.01) chosen based on contrast-to-noise ratio (CNR). Dosimetry performance was assessed by determining percentage dose depth (PDD) for a 6MV beam with a 5 × 5 cm2 field using FXO-f gel dosimeter, compared with ionization chamber data. ResultsMTF evaluation yielded ≥ 50 % agreement with pattern charts. Stray-to-primary ratio was less than 0.1 or 10 % of the total signal. Reconstruction showed low noise and artifacts, with optimal CNR at λ = 0.01. Attenuation coefficients from optical CT aligned with spectrometer measurements within 1.2 %. PDD calculated with FXO-f gel dosimeter closely matched ionization chamber data (<1.2 % difference), achieving a dose resolution of 0.1 Gy. ConclusionThe built and optimization the de optical-CT based on a convergent beam is read to perform the 3D quality assurance in clinical applications.

H-BN layered material: A new frontier in radiation dosimetry

This study explores the potential of hexagonal boron nitride (h-BN) nanostructures for dosimetry of diverse ionizing radiation. We focus on the crucial thermoluminescence (TL) properties of h-BN, including glow curve, dose-response, reproducibility, sensitivity, and fading, within the conventional framework of TL dosimetry. The h-BN powder samples were exposed to different ionizing radiations, including 60Co gamma-rays with a mean energy of 1.25 MeV, electrons (6 MeV), and photons (6 MV), at levels of dose familiar in radiotherapy ranging from 2 Gy to 15 Gy. The h-BN's effective atomic number of 6.25, similar to human tissue, opens up exciting possibilities for applications in medical imaging and dosimetry. Notably, h-BN demonstrates a linear response within the dose range of interest, showcasing excellent sensitivity, particularly at low doses and low photon energies. Additionally, h-BN samples exhibit remarkable reproducibility, with a standard deviation of less than 2.4%, albeit accompanied by significant fading. Regarding the trapping parameters underpinning the manifestation of the glow curves of the irradiated samples, use was made of the peak shape method with different models to estimate the order of kinetics (b), activation energy (E), and frequency factor (s) or escape probability and trap lifetime (τ). The data suggest that the TL glow peaks of the h-BN obey general-order kinetics. These findings underscore the transformative potential of h-BN layered material in advancing radiation dosimetry, particularly in medical physics fields. The inherent characteristics of h-BN, coupled with its effective atomic number, excellent linearity over a wide range of radiation doses especially for electron irradiation and better reproducibility, positioned it as a suitable tool for precise and reliable dose measurement in medical imaging and therapy, heralding a new frontier in radiation dosimetry.

Thermoluminescence response of carbon ion beam irradiated LiCaAlF6: Tb phosphor

Accurate measurement of the dose delivered to patients is crucial in any radiation therapy, including C ion beam radiotherapy, to ensure effective treatment and minimize the risk of damage to healthy tissues. The accessibility of thermoluminescence (TL) - based materials for carbon ion beam dosimetry continues to be constrained. With the aim of this, an investigation has been done to study the TL properties of the Terbium (Tb) doped LiCaAlF6 phosphor following irradiation with C ion beam. The LiCaAlF6: Tb phosphor has been synthesized using melting method in argon gas atmosphere. TL glow curves has been analyzed on exposure to carbon ion beams at energies of 85 MeV and 50 MeV within the fluence range of 109 - 1012 ions/cm2. The TRIM code, relying on Monte Carlo simulation, has been employed to compute parameters such as absorbed dose, ion range, and energy loss. The Tb-doped LiCaAlF6 phosphor exhibits a glow curve structure with distinctly resolved peaks at 130 °C and 325 °C. Notably, the TL intensity has been significantly increased by 105 times than that of undoped LiCaAlF6. This enhancement is attributed to the generation of a high density of Tb-associated defects within the energy band gap. The TL enhancement has been elucidated based on charge compensation mechanism. Further, TL glow curve shape and structure remain consistent across different energies, i.e., 85 and 50 MeV C ion beams, indicating an energy-independent behavior of this phosphor. Nevertheless, the TL intensity at 85 MeV is higher compared to that at 50 MeV. Detailed dosimetry properties have been investigated for 85 MeV C ion beams within the fluence range 2x109-5x1012 ions/cm2. The phosphor exhibits a sublinear dependence against dose for the studied fluence range with no discernible shift in peak position. The favorable outcomes include low fading during the initial days of storage time and batch homogeneity. TL glow curve analysis indicate the formation of trapping level in the range of 0.90–1.72eV within the band gap of the phosphor which are responsible for TL process. The phosphor's simple glow curve structure, minimal fading, consistent batch homogeneity and high stability of the glow curve suggest that the material can be explored for C ion beam dosimetry application.

Feasibility study for the development of multilayered solar cells for proton linear energy transfer depth profile measurement.

Previous study proposed a method to measure linear energy transfer (LET) at specific points using the quenching magnitude of thin film solar cells. This study was conducted to propose a more advanced method for measuring the LET distribution. This study focuses on evaluating the feasibility of estimating the proton LET distribution in proton therapy. The feasibility of measuring the proton LET and dose distribution simultaneously using a single-channel configuration comprising two solar cells with distinct quenching constants is investigated with the objective of paving the way for enhanced proton therapy dosimetry. Two solar cells with different quenching constants were used to estimate the proton LET distribution. Detector characteristics (e.g., dose linearity and dose-rate dependency) of the solar cells were evaluated to assess their suitability for dosimetry applications. First, using a reference beam condition, the quenching constants of the two solar cells were determined according to the modified Birks equation. The signal ratios of the two solar cells were then evaluated according to proton LET in relation to the estimated quenching constants. The proton LET distributions of six test beams were obtained by measuring the signal ratios of the two solar cells at each depth, and the ratios were evaluated by comparing them with those calculated by Monte Carlo simulation. The detector characterization of the two solar cells including dose linearity and dose-rate dependence affirmed their suitability for use in dosimetry applications. The maximum difference between the LET measured using the two solar cells and that calculated by Monte Carlo simulation was 2.34keV/µm. In the case of the dose distribution measured using the method proposed in this study, the maximum difference between range measured using the proposed method and that measured using a multilayered ionization chamber was 0.7mm. The expected accuracy of simultaneous LET and dose distribution measurement using the method proposed in this study were estimated to be 3.82%. The signal ratios of the two solar cells, which are related to quenching constants, demonstrated the feasibility of measuring LET and dose distribution simultaneously. The feasibility of measuring proton LET and dose distribution simultaneously using two solar cells with different quenching constants was demonstrated. Although the method proposed in this study was evaluated using a single channel by varying the measuring depth, the results suggest that the proton LET and dose distribution can be simultaneously measured if the detector is configured in a multichannel form. We believe that the results presented in this study provide the envisioned transition to a multichannel configuration, with the promise of substantially advancing proton therapy's accuracy and efficacy in cancer treatment.

Dosimetric characteristics of 3D-printed and epoxy-based materials for particle therapy phantoms

Objective3D printing has seen use in many fields of imaging and radiation oncology, but applications in (anthropomorphic) phantoms, especially for particle therapy, are still lacking. The aim of this work was to characterize various available 3D printing methods and epoxy-based materials with the specific goal of identifying suitable tissue surrogates for dosimetry applications in particle therapy.Methods3D-printed and epoxy-based mixtures of varying ratios combining epoxy resin, bone meal, and polyethylene powder were scanned in a single-energy computed tomography (CT), a dual-energy CT, and a µCT scanner. Their CT-predicted attenuation was compared to measurements in a 148.2 MeV proton and 284.7 MeV/u carbon ion beam. The sample homogeneity was evaluated in the respective CT images and in the carbon beam, additionally via widening of the Bragg peak. To assess long-term stability attenuation, size and weight measurements were repeated after 6–12 months.ResultsFour 3D-printed materials, acrylonitrile butadiene styrene polylactic acid, fused deposition modeling printed nylon, and selective laser sintering printed nylon, and various ratios of epoxy-based mixtures were found to be suitable tissue surrogates. The materials’ predicted stopping power ratio matched the measured stopping power ratio within 3% for all investigated CT machines and protocols, except for µCT scans employing cone beam CT technology. The heterogeneity of the suitable surrogate samples was adequate, with a maximum Bragg peak width increase of 11.5 ± 2.5%. The repeat measurements showed no signs of degradation after 6–12 months.ConclusionWe identified surrogates for soft tissue and low- to medium-density bone among the investigated materials. This allows low-cost, adaptable phantoms to be built for quality assurance and end-to-end tests for particle therapy.