Artykuły w czasopismach: „Gel dosimeters”

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Alhassan, M., A. Abdulrahman i I. S. Mustafa. "Response of 2-Hydroxymethyl Methacrylate Polymer Gel Dosimeter with Maltose Additive for Radiation within Diagnostic X-Ray Energies". Journal of Applied Sciences and Environmental Management 27, nr 4 (30.04.2023): 849–52. http://dx.doi.org/10.4314/jasem.v27i4.29.

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The use of polymer gel dosimeters (PGD) in x-ray radiography has not yet been confirmed. However, if it could be applied, it could help to improve patient dosimetry, dose optimization, and quality assurance through its three-dimensional (3D) image display. This research aimed to evaluate the response of a 2-hydroxymethyl methacrylate (HEMA) polymer gel dosimeter at lower energies for possible use in diagnostic x-ray radiography and to determine the effect of maltose concentrations on the sensitivity. The dosimeter was made under normoxic conditions using Gelatin, HEMA, N, N’- Methylene – bis – acrylamide (BIS), Ascorbic Acid, deionized water, and maltose of various concentrations (10 – 50 mM). The PGDs were then irradiated using a conventional x-ray machine with exposure settings ranging from 10-200 mA, 40-100 kV, and s = 1 s. Afterward, the irradiated dosimeters were scanned using UV-spectroscopy. The result showed that the dosimeters responded to low-energy x-rays, and the effect of the maltose concentration within the tested range was not linear with the sensitivity. We concluded that the HEMA polymer gel dosimeter could be used for clinical x-ray dosimetry, but further research on the effect of maltose concentrations on the sensitivity is needed.

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Gafar, Sameh Mohamed, i Nehad Magdy Abdel-Kader. "Radiation induced degradation of murexide dye in two media for possible use in dosimetric applications". Pigment & Resin Technology 48, nr 6 (4.11.2019): 540–46. http://dx.doi.org/10.1108/prt-02-2019-0014.

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Purpose The purpose of this paper is to study the effect of gamma-rays on murexide (Mx) dye and its possible use as radiation dosimeters in two different dosimetry systems. The first system depends on the Mx dye as a liquid dosimeter. The second dosimetry system depends also on the same dye but as in a gel form, which is more sensitive to gamma-rays. Design/methodology/approach The prepared Mx (solutions/gels) have a considerable two peaks at 324 and 521 nm that upon irradiation, the intensity of these peaks decreases with the increasing radiation dose. Findings The gamma-ray absorbed dose for these dosimeters was found to be up to 2 kGy for the solution samples and 40 Gy for the gels. Radiation chemical yield, dose response function, radiation sensitivity and before and after-irradiation stability under various conditions were discussed and studied. Practical implications It is expected that the radiolysis of the Mx dye can be used as radiation dosimeters in two different dosimetry systems; liquid and gel dosimeters. This can be applied in a wide range of gamma radiation practical industrial applications in water treatment, food irradiation dosimeters, radiotherapy and fresh food irradiation and seed production. Originality/value Both of the prepared Mx dyes, either as solutions or gel samples, can be facilely prepared from commercially, cheap, safe, available chemicals and suitable for useful applied Mx solutions and gels radiation dosimeters.

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De Deene, Yves. "Radiation Dosimetry by Use of Radiosensitive Hydrogels and Polymers: Mechanisms, State-of-the-Art and Perspective from 3D to 4D". Gels 8, nr 9 (19.09.2022): 599. http://dx.doi.org/10.3390/gels8090599.

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Gel dosimetry was developed in the 1990s in response to a growing need for methods to validate the radiation dose distribution delivered to cancer patients receiving high-precision radiotherapy. Three different classes of gel dosimeters were developed and extensively studied. The first class of gel dosimeters is the Fricke gel dosimeters, which consist of a hydrogel with dissolved ferrous ions that oxidize upon exposure to ionizing radiation. The oxidation results in a change in the nuclear magnetic resonance (NMR) relaxation, which makes it possible to read out Fricke gel dosimeters by use of quantitative magnetic resonance imaging (MRI). The radiation-induced oxidation in Fricke gel dosimeters can also be visualized by adding an indicator such as xylenol orange. The second class of gel dosimeters is the radiochromic gel dosimeters, which also exhibit a color change upon irradiation but do not use a metal ion. These radiochromic gel dosimeters do not demonstrate a significant radiation-induced change in NMR properties. The third class is the polymer gel dosimeters, which contain vinyl monomers that polymerize upon irradiation. Polymer gel dosimeters are predominantly read out by quantitative MRI or X-ray CT. The accuracy of the dosimeters depends on both the physico-chemical properties of the gel dosimeters and on the readout technique. Many different gel formulations have been proposed and discussed in the scientific literature in the last three decades, and scanning methods have been optimized to achieve an acceptable accuracy for clinical dosimetry. More recently, with the introduction of the MR-Linac, which combines an MRI-scanner and a clinical linear accelerator in one, it was shown possible to acquire dose maps during radiation, but new challenges arise.

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Dhakal, Rabin, Mohammad Yosofvand i Hanna Moussa. "Development and Application of MAGIC-f Gel in Cancer Research and Medical Imaging". Applied Sciences 11, nr 17 (24.08.2021): 7783. http://dx.doi.org/10.3390/app11177783.

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Much of the complex medical physics work requires radiation dose delivery, which requires dosimeters to accurately measure complex three-dimensional dose distribution with good spatial resolution. MAGIC-f polymer gel is one of the emerging new dosimeters widely used in medical physics research. The purpose of this study was to present an overview of polymer gel dosimetry, using MAGIC-f gel, including its composition, manufacture, imaging, calibration, and application to medical physics research. In this review, the history of polymer gel development is presented, along with the applications so far. Moreover, the most important experiments/applications of MAGIC-f polymer gel are discussed to illustrate the behavior of gel on different conditions of irradiation, imaging, and manufacturing techniques. Finally, various future works are suggested based on the past and present works on MAGIC-f gel and polymer gel in general, with the hope that these bits of knowledge can provide important clues for future research on MAGIC-f gel as a dosimeter.

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Yang, Tao, Junhui Wang, Jiali Tu, Xiaoxi Zhou, Jiamin Sun, Jian Chen, Wanxin Wen i Yanfei Wang. "Rare-earth doped radioluminescent hydrogel as a potential phantom material for 3D gel dosimeter". e-Polymers 21, nr 1 (1.01.2021): 616–24. http://dx.doi.org/10.1515/epoly-2021-0053.

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Abstract Cancer prevention and treatment are currently the focus of most research. Dose verification is an important step for reducing the improper dose deposition during radiotherapy. To mend the traditional gel dosimeters for 3D dose verification, a novel rare-earth nanoparticle-based composite gel was prepared, which has good radioluminescence property and reusability. It is a promising phantom material for the new 3D gel dosimeter. TEM, DLS, FT-IR, TGA, and spectrofluorometer were used to determine the chemical structure, micromorphology, and optical performance. Compared to the traditional gel dosimeters, the composite gel has a good linear relationship between the light intensity excited by X-ray and the tube current. Furthermore, it may measure the dose distribution immediately in situ, which reduces errors and saves time. This work provides a new idea for the research of 3D gel dosimeters and promotes the safe and effective use of radiotherapy.

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Toyohara, Masumitsu, Shinichi Minohara, Yohsuke Kusano, Hiroaki Gotoh, Yoichiro Tanaka, Masaru Yuhara, Yu Yamashita i Yoshiaki Shimono. "Induced Radionuclides and Their Activity Concentration in Gel Dosimeters Irradiated by Carbon Ion Beam". Gels 8, nr 4 (23.03.2022): 203. http://dx.doi.org/10.3390/gels8040203.

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Radioactivity was measured in a micellar gel dosimeter, a polymer gel dosimeter, and water was irradiated by carbon ion beams at various beam energy conditions. Monte Carlo simulation was also performed to estimate the radioactivity. Short-lived positron-emitting nuclides were observed immediately after irradiation, but they decayed rapidly into the background. At 24 h post-irradiation, the dominant measured radioactivity was of 7Be. The simulation also showed minor activity of 24Na and 3H; however, they were not experimentally observed. The measured radioactivity was independent of the type of gel dosimeter under all irradiation conditions, suggesting that the radioactivity was induced by the interaction of carbon ions with water (the main component of the gel dosimeters). The ratio between the simulated and measured radioactivity was within 0.9–1.5. The activity concentration of 7Be was found to be less than 1/10 of the value derived using the exemption concept proposed by the International Atomic Energy Agency. This result should be applicable to irradiated gel dosimeters containing mainly water and 0–4 wt.% C and 0–1.7 wt.% N.

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Siti, K. A. R., S. M. Iskandar, A. R. Azhar, M. R. Ramzun i Mohamed Kamari Halimah. "Acoustic Evaluation of Hema Polymer Gel Dosimeter Phantoms". Advanced Materials Research 895 (luty 2014): 169–73. http://dx.doi.org/10.4028/www.scientific.net/amr.895.169.

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A new method for the evaluation of radiotherapy 3D polymer gel dosimeters has been developed using ultrasound to assess the significant structural changes that occur following irradiation of the dosimeters. Polymer gel dosimeters were being fabricated using a monomer named 2-Hydroxyl-Ethyl-Meta-Acrylate (HEMA) with the presence of gelatine as a gelling agent. The readymade gel which is the concentration for HEMA fixed at 2, 4 and 5% would then undergo an ultrasonic evaluation to test for the propagation of sound speed through it. In the observation of relationship between the ultrasound propagation speeds as the doses increase (focusing at the cross region from overlapped beams) and concentration of monomer, the propagation speed for all the three polymer gel dosimeter phantoms still varies between 1460 to 1570 m/s which is still in the range of speed of sound for human tissue [. The ultrasonic absorption attenuation coefficient dose sensitivity for polymer gel dosimeters for 2, 4 and 5% of monomer are in the range of 0.02 to 0.6 dB which is equivalent to human tissue. As a comparison, it can be seen that gel phantoms with high concentration of monomer (5%) is more sensitive to the radiation compared to the lower (2% and 4%) concentrations. Regarding the absolute results of mechanical and acoustic properties; the copolymer-in-oil phantom is equivalent with soft tissue.

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Zhu, Libing, Yi Du, Yahui Peng, Xincheng Xiang i Xiangang Wang. "End-to-End QA with Polymer Gel Dosimeter for Photon Beam Radiation Therapy". Gels 9, nr 3 (10.03.2023): 212. http://dx.doi.org/10.3390/gels9030212.

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With the complexity and high demands on quality assurance (QA) of photon beam radiation therapy, end-to-end (E2E) QA is necessary to validate the entire treatment workflow from pre-treatment imaging to beam delivery. A polymer gel dosimeter is a promising tool for three-dimensional (3D) dose distribution measurement. The purpose of this study is to design a fast “one delivery” polymethyl methacrylate (PMMA) phantom with a polymer gel dosimeter for the E2E QA test of the photon beam. The one delivery phantom is composed of ten calibration cuvettes for the calibration curve measurement, two 10 cm gel dosimeter inserts for the dose distribution measurement, and three 5.5 cm gel dosimeters for the square field measurement. The one delivery phantom holder is comparable in size and shape to that of a human thorax and abdomen. In addition, an anthropomorphic head phantom was employed to measure the patient-specific dose distribution of a VMAT plan. The E2E dosimetry was verified by undertaking the whole RT procedure (immobilization, CT simulation, treatment planning, phantom set-up, imaged-guided registration, and beam delivery). The calibration curve, field size, and patient-specific dose were measured with a polymer gel dosimeter. The positioning error can be mitigated with the one-delivery PMMA phantom holder. The delivered dose measured with a polymer gel dosimeter was compared with the planned dose. The gamma passing rate is 86.64% with the MAGAT-f gel dosimeter. The results ascertain the feasibility of the one delivery phantom with a polymer gel dosimeter for a photon beam in E2E QA. The QA time can be reduced with the designed one delivery phantom.

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Zhu, Libing, Manzhou Zhang, Xincheng Xiang i Xiangang Wang. "3D Proton Bragg Peak Visualization and Spot Shape Measurement with Polymer Gel Dosimeters". Applied Sciences 12, nr 19 (29.09.2022): 9839. http://dx.doi.org/10.3390/app12199839.

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Proton pencil beam scanning is a dynamic beam delivery technique with excellent conformability to the tumor volume. The accuracy of spot size and scanning positions will have a significant effect on the delivered dose distribution. We employed polymer gel dosimeters to measure the spot size and the scanning positions for the Shanghai Advanced Proton Therapy facility (SAPT). Polymer gel dosimeters (MAGAT-f and PAGAT) were utilized to measure the full width at half maximum (FWHM) of the beam spot at various depths on the basis of their MRI readouts. The correlation between the spot FWHM and standard deviation (σ) was analyzed at different depths. The measured Bragg peak range was compared with the Monte Carlo (MC) simulation. Three-dimensional volume rendering of the Bragg peak was reconstructed for the 3D visualization to measure the spot size three-dimensionally. The R2 dose–response curve was investigated with polymer gel dosimeters. The deviations of the Bragg peak ranging between measurement and simulation were 0.13% and −0.53% for MAGAT-f and PAGAT, respectively. Our results ascertain the feasibility of a polymer gel dosimeter to measure the spot size and positions of a proton pencil beam.

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Sąsiadek-Andrzejczak, Elżbieta, Agata Mądrakowska i Marek Kozicki. "Study of NBT–Pluronic F–127 Gels as 1D UV Radiation Dosimeters for Measurement of Artificial Light Sources". Materials 15, nr 7 (23.03.2022): 2370. http://dx.doi.org/10.3390/ma15072370.

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This work reports on radiochromic dosimeters for 1D UV light measurements. The dosimeter is composed of a 25% Pluronic F–127 that forms a physical gel matrix and nitro blue tetrazolium chloride (NBT) as a radiation-sensitive compound. This dosimeter was exposed to UVA, UVB and UVC radiation, and the radiochromic reactions were followed with reflectance spectrophotometry including changes in light reflectance and color coordinates in the CIELAB color system. The exposition of dosimeters to all UV radiation caused color changes from pale yellow to dark violet, and its intensity increased with increasing absorbed dose. The effects of NBT concentration and UV radiation type on the dose–response of the dosimeters were also examined. The results obtained reveal that the dosimeters are the least sensitive to irradiation with UVC and the most sensitive to irradiation with UVB (e.g., dosimeter with 2 g/dm3 of NBT was characterized by the following parameters: the threshold dose 0.1 J/cm2; the dose sensitivity −5.97 ± 0.69 cm2/J; the linear dose range 0.1–2.5 J/cm2; the dynamic dose range was equal to 0.1–3 J/cm2). The results obtained reveal that the NBT–Pluronic F–127 dosimeters can be potentially useful as 1D sensors for artificial UV radiation sources measurements.

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Mizukami, Shinya, Yusuke Watanabe, Takahiro Mizoguchi, Tsutomu Gomi, Hidetake Hara, Hideyuki Takei, Nobuhisa Fukunishi, Kenichi L. Ishikawa, Shigekazu Fukuda i Takuya Maeyama. "Whole Three-Dimensional Dosimetry of Carbon Ion Beams with an MRI-Based Nanocomposite Fricke Gel Dosimeter Using Rapid T1 Mapping Method". Gels 7, nr 4 (25.11.2021): 233. http://dx.doi.org/10.3390/gels7040233.

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MRI-based gel dosimeters are attractive systems for the evaluation of complex dose distributions in radiotherapy. In particular, the nanocomposite Fricke gel dosimeter is one among a few dosimeters capable of accurately evaluating the dose distribution of heavy ion beams. In contrast, reduction of the scanning time is a challenging issue for the acquisition of three-dimensional volume data. In this study, we investigated a three-dimensional dose distribution measurement method for heavy ion beams using variable flip angle (VFA), which is expected to significantly reduce the MRI scanning time. Our findings clarified that the whole three-dimensional dose distribution could be evaluated within the conventional imaging time (20 min) and quality of one cross-section.

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Mohyedin, Muhammad Zamir, Hafiz Mohd Zin, Mohd Zulfadli Adenan i Ahmad Taufek Abdul Rahman. "A Review of PRESAGE Radiochromic Polymer and the Compositions for Application in Radiotherapy Dosimetry". Polymers 14, nr 14 (16.07.2022): 2887. http://dx.doi.org/10.3390/polym14142887.

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Recent advances in radiotherapy technology and techniques have allowed a highly conformal radiation to be delivered to the tumour target inside the body for cancer treatment. A three-dimensional (3D) dosimetry system is required to verify the accuracy of the complex treatment delivery. A 3D dosimeter based on the radiochromic response of a polymer towards ionising radiation has been introduced as the PRESAGE dosimeter. The polyurethane dosimeter matrix is combined with a leuco-dye and a free radical initiator, whose colour changes in proportion to the radiation dose. In the previous decade, PRESAGE gained improvement and enhancement as a 3D dosimeter. Notably, PRESAGE overcomes the limitations of its predecessors, the Fricke gel and the polymer gel dosimeters, which are challenging to fabricate and read out, sensitive to oxygen, and sensitive to diffusion. This article aims to review the characteristics of the radiochromic dosimeter and its clinical applications. The formulation of PRESAGE shows a delicate balance between the number of radical initiators, metal compounds, and catalysts to achieve stability, optimal sensitivity, and water equivalency. The applications of PRESAGE in advanced radiotherapy treatment verifications are also discussed.

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Peleg Walg, Yarden, Yanai Krutman, Amir Berman i Itzhak Orion. "Synchrotron X-ray Irradiation of a Rat’s Head Model: Monte Carlo Study of Chromatic Gel Dosimetry". Applied Sciences 11, nr 16 (11.08.2021): 7389. http://dx.doi.org/10.3390/app11167389.

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Accurate treatment planning in radiotherapy essentially decreases damage to healthy tissue surrounding the tumor. Due to plans to use a direct, highly collimated, narrow beam with high intensity to treat small area tumors, researchers have studied microbeam radiation therapy extensively. Using a synchrotron beam as the radiation source may help to limit damage, but treatment planning using computerized simulations and dosimetry is still necessary to achieve optimal results. For this purpose, PDA-gel dosimeters were developed and their sensitivity around a 150 keV induced synchrotron X-ray radiation beam was examined via Monte Carlo simulations using the EGS5 code system. The microbeam development is now at the animal study stage. In this study, we simulate the irradiation of a rat’s brain. The simulation results obtained spectra for two types of PDA-gel dosimeters that were compared with the spectrum obtained in a modelized brain tumor of a rat. Additionally, percentage depth dose curves were calculated for the brain tissue and the two gels. Correction equations for the dosimeters were obtained from the dose-difference plots. For further references, these equations can be used to calculate the actual dose in a brain tumor in a rat. The Monte Carlo simulations demonstrate that PDA-gel dosimeters can be used for treatment planning using synchrotron irradiations.

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Zhang, Wei, Kaikai Wang, Yufeng Zeng, Xiaodan Hu, Xiaohong Zhang, Shuquan Chang i Haiqian Zhang. "Low-Diffusion Fricke Gel Dosimeters with Core-Shell Structure Based on Spatial Confinement". Materials 14, nr 14 (14.07.2021): 3932. http://dx.doi.org/10.3390/ma14143932.

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The diffusion of ferric ions is an important challenge to limit the application of Fricke gel dosimeters in accurate three-dimensional dose verification of modern radiotherapy. In this work, low-diffusion Fricke gel dosimeters, with a core-shell structure based on spatial confinement, were constructed by utilizing microdroplet ultrarapid freezing and coating technology. Polydimethylsiloxane (PDMS), with its excellent hydrophobicity, was coated on the surface of the pellets. The concentration gradient of the ferric ion was realized through shielding half of a Co-60 photon beam field size, and ion diffusion was measured by both ultraviolet-visible spectrophotometry and magnetic resonance imaging. No diffusion occurred between the core-shell pellets, even at 96 h after irradiation, and the diffusion length at the irradiation boundary was limited to the diameter (2–3 mm) of the pellets. Furthermore, Monte Carlo calculations were conducted to study dosimetric properties of the core-shell dosimeter, which indicated that a PDMS shell hardly affected the performance of the dosimeter.

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McAuley, K. B., i A. T. Nasr. "Fundamentals of gel dosimeters". Journal of Physics: Conference Series 444 (26.06.2013): 012001. http://dx.doi.org/10.1088/1742-6596/444/1/012001.

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Kozicki, Marek, Malwina Jaszczak, Mariusz Dudek i Piotr Maras. "Laser Light Trapping Phenomenon in a 3D Radiotherapy Polymer Gel Dosimeter". Materials 14, nr 14 (15.07.2021): 3961. http://dx.doi.org/10.3390/ma14143961.

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This paper aims to explain the phenomenon of laser light trapping (LLT) in a 3D polymer gel dosimeter. A VIC-T polymer gel dosimeter containing 17% N-vinylpyrrolidone, 8% N,N′-methylenebisacrylamide, 12% tert-butyl alcohol, 5% gelatine, 0.02% hydroquinone and 14 mM tetrakis(hydroxymethyl)phosphonium chloride was used in this study. It was exposed to green laser light with a wavelength of 532 nm. A film was recorded during the exposure. After exposure, Raman spectroscopy was used to study the reactions taking place inside the dosimeter. The obtained results were used to explain what the LLT phenomenon is, what are the consequences for the dosimeter in which such a phenomenon occurs, and what dosimeter components play an important role in the occurrence of LLT. In addition, the conditions under which 3D polymer gel dosimeters can be measured using optical computed tomography at short wavelengths of visible laser light are indicated.

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Rintoul, L., M. Lepage i C. Baldock. "Radiation Dose Distribution in Polymer Gels by Raman Spectroscopy". Applied Spectroscopy 57, nr 1 (styczeń 2003): 51–57. http://dx.doi.org/10.1366/000370203321165205.

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The Raman spectroscopy of polymer gel dosimeters has been investigated with a view to developing a novel dosimetry technique that is capable of determining radiation dose within a micrometer of spatial resolution. The polymer gel dosimeter, known as the PAG dosimeter, is typically made up of acrylamide, N,N′-methylene-bis-acrylamide, gelatin, and water. A polyacrylamide network within the gelatin matrix forms in response to an absorbed dose. The loss of monomers may be monitored by corresponding changes to the Raman spectrum. Principal component analysis offers a simple method of quantifying the absorbed radiation dose from the Raman spectrum of the polymer gel. The background luminescence in the spectrum increased significantly with dose and is shown to originate in the glass of the sample vial. The competing effects of elastic scatter, which increases with dose due to the formation of polymer, and sample absorption were quantified and found to introduce errors of up to 5% under certain conditions. Raman spectra as a function of distance from the air–surface interface have been measured for samples that were subjected to doses delivered by a clinical linear accelerator. The depth dose profile thus obtained compared favorably with “gold standard” ion-chamber measurements.

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Ogilvy, A., S. Collins, W. Hare, M. Hilts, T. Tuokko, R. Deardon i A. Jirasek. "Simulated design optimization of a prototype solid tank optical CT scanner for 3D radiation dosimetry". Journal of Physics: Conference Series 2167, nr 1 (1.01.2022): 012009. http://dx.doi.org/10.1088/1742-6596/2167/1/012009.

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Abstract Optical computed tomography (CT) is one of the leading modalities for imaging gel dosimeters. There exist many prototype designs, as well as some commercial optical CT scanners that have showcased the value that gel dosimeters can provide to improve 3D dose verification for radiation treatments. However, due to factors including image accuracy, scan time, or demanding setup and maintenance there is currently no single scanner that has become a ubiquitous staple in a clinical setting. In this work, a prototype solid tank optical CT scanner is proposed that minimizes the need for a refractive index bath commonly found in optical CT systems. In addition to the design proposal, a ray-path simulator was created to optimize the design such that the solid tank geometry improves light collection across the detector array, maximizes the volume of the dosimeter scanned, and maximizes the dynamic range of the scanner.

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Soliman, Yasser S., Soad M. Tadros, Wafaa B. Beshir, Gamal R. Saad, Salvatore Gallo, Laila I. Ali i Magdi M. Naoum. "Study of Ag Nanoparticles in a Polyacrylamide Hydrogel Dosimeters by Optical Technique". Gels 8, nr 4 (5.04.2022): 222. http://dx.doi.org/10.3390/gels8040222.

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The dosimetric characteristics of hydrogel dosimeters based on polyacrylamide (PAC) as a capping agent incorporating silver nitrate as a radiation-sensitive material are investigated using UV-Vis spectrophotometry within the dose range 0–100 Gy. Glycerol was used in the hydrogel matrix to promote the dosimetric response and increase the radiation sensitivity. Upon exposing the PAC hydrogel to γ-ray, it exhibits a Surface Plasmon Resonance (SPR) band at 453 nm, and its intensity increases linearly with absorbed doses up to 100 Gy. The results are compared with the silver nitrate gel dosimeter. Glycerol of 15% in the hydrogel matrix enhances the radiation sensitivity by about 30%. PAC hydrogel dosimeter can be considered a near water equivalent material in the 400 keV–20 MeV photon energy range. At doses less than 15 Gy, the PAC hydrogel dosimeter retains higher radiation sensitivity than the gel dosimeter. The total uncertainty (2σ) of the dose estimated using this hydrogel is about 4%. These results may support the validity of using this hydrogel as a dosimeter to verify radiotherapy techniques and dose monitoring during blood irradiation.

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Wolfel, A., D. Chacón, M. R. Romero, M. Valente i F. Mattea. "DEVELOPMENT OF POLYMERIC MATERIALS FOR X-RAY DOSIMETRY WITH ENHANCED OPTICAL SENSIBILITY". Anales AFA 31, nr 3 (2020): 101–6. http://dx.doi.org/10.31527/analesafa.2020.31.3.101.

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The use of a new reagent with the capacity of forming colored organo-metallic complexes with metal ions is herein studied for its application in X-Ray dosimetry, aiming to assess its effect on the dose-sensitivity of polymer gel dosimetry. The improvement of the sensitivity of polymeric dosimeters, commonly used to quantitatively register dose distribution in radiotherapy, requires considering both the intrinsic mechanism involved in the irradiation of the dosimetry system (polymerization) and the selected readout technique (e.g. spectroscopy techniques). One of the most used readout methods is measuring the change in the optical density of the dosimeters after their irradiation. The formulation of a new sensitive material able to form organo-metallic complexes and the potentiality of achieving significant changes in the optical density in the irradiated region is studied in this work. For this purpose, a new monomer (GMA-IDA) was synthesized and used in the polymerization with other monomers, commonly employed in polymer gel dosimetry (acrylamide, N,N’-methylenebisacrylamide y N-isopropilacrylamide. The polymerization of the new sensitive material was initiated by a redox reaction (APS/TEMED) or by ionizing radiation (X-Rays), then the effect of the new monomer over the performance of the dosimetry material was evaluated. Results indicated that the new formed polymer has the capacity of forming colored complexes with Cu2+.

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Bäck, Sven ÅJ. "Clinical applications of gel dosimeters". Journal of Physics: Conference Series 164 (1.05.2009): 012049. http://dx.doi.org/10.1088/1742-6596/164/1/012049.

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Schreiner, L. J. "Review of Fricke gel dosimeters". Journal of Physics: Conference Series 3 (1.01.2004): 9–21. http://dx.doi.org/10.1088/1742-6596/3/1/003.

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McAuley, Kim B. "Fundamentals of Polymer Gel Dosimeters". Journal of Physics: Conference Series 56 (1.12.2006): 35–44. http://dx.doi.org/10.1088/1742-6596/56/1/004.

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PhD, Geoffrey S. Ibbott,. "Clinical Applications of Gel Dosimeters". Journal of Physics: Conference Series 56 (1.12.2006): 108–31. http://dx.doi.org/10.1088/1742-6596/56/1/010.

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Rabaeh, Khalid A., Rawan E. Al-Tarawneh, Molham M. Eyadeh, Issra’ M. E. Hammoudeh i Moneeb T. M. Shatnawi. "Improved Dose Response of N-(hydroxymethyl)acrylamide Gel Dosimeter with Calcium Chloride for Radiotherapy". Gels 8, nr 2 (26.01.2022): 78. http://dx.doi.org/10.3390/gels8020078.

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The impact of calcium chloride (CaCl2) on the performance of N-(hydroxymethyl)acrylamide (NHMA) polymer gel dosimeter is studied in this article. The dosimeter was exposed to doses of up to 10 Gy with radiation beam-energy of 10 MV and dose-rates of 300 cGy/min. The relaxation rate (R2) parameter was utilized to explore the performance of irradiated NHMAGAT gels. The dose response in terms of R2 increased from 0.29 to 0.63 Gy−1·s−1 with increasing calcium chloride concentration from 0 to 1000 mM. The results show no substantial impact of dose-rates as well as radiation energies on NHMAGAT samples. For the steadiness of irradiated NHMAGAT dosimeters, it was found that there is no apparent variation in R2 (less than ±3%; standard deviation) up to 3 days. The overall uncertainty of the gel dosimeter with calcium chloride is 4.96% (double standard deviation, 95% confidence level).

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Macchione, Micaela A., Sofía Lechón Páez, Miriam C. Strumia, Mauro Valente i Facundo Mattea. "Chemical Overview of Gel Dosimetry Systems: A Comprehensive Review". Gels 8, nr 10 (17.10.2022): 663. http://dx.doi.org/10.3390/gels8100663.

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Advances in radiotherapy technology during the last 25 years have significantly improved both dose conformation to tumors and the preservation of healthy tissues, achieving almost real-time feedback by means of high-precision treatments and theranostics. Owing to this, developing high-performance systems capable of coping with the challenging requirements of modern ionizing radiation is a key issue to overcome the limitations of traditional dosimeters. In this regard, a deep understanding of the physicochemical basis of gel dosimetry, as one of the most promising tools for the evaluation of 3D high-spatial-resolution dose distributions, represents the starting point for developing new and innovative systems. This review aims to contribute thorough descriptions of the chemical processes and interactions that condition gel dosimetry outputs, often phenomenologically addressed, and particularly formulations reported since 2017.

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Penev, Kalin I., Matt Mulligan i Kibret Mequanint. "Optimization of the Dose Rate Effect in Tetrazolium Gellan Gel Dosimeters". Gels 9, nr 4 (14.04.2023): 334. http://dx.doi.org/10.3390/gels9040334.

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Tetrazolium salts provide an appealing candidate for 3D gel dosimeters as they exhibit a low intrinsic color, no signal diffusion and excellent chemical stability. However, a previously developed commercial product (the ClearView 3D Dosimeter) based on a tetrazolium salt dispersed within a gellan gum matrix presented a noticeable dose rate effect. The goal of this study was to find out whether ClearView could be reformulated in order to minimize the dose rate effect by optimizing of the tetrazolium salt and gellan gum concentrations and by the addition a thickening agent, ionic crosslinkers, and radical scavengers. To that goal, a multifactorial design of experiments (DOE) was conducted in small-volume samples (4-mL cuvettes). It showed that the dose rate could be effectively minimized without sacrificing the integrity, chemical stability, or dose sensitivity of the dosimeter. The results from the DOE were used to prepare candidate formulations for larger-scale testing in 1-L samples to allow for fine-tuning the dosimeter formulation and conducting more detailed studies. Finally, an optimized formulation was scaled-up to a clinically relevant volume of 2.7 L and tested against a simulated arc treatment delivery with three spherical targets (diameter 3.0 cm), requiring different doses and dose rates. The results showed excellent geometric and dosimetric registration, with a gamma passing rate (at 10% minimum dose threshold) of 99.3% for dose difference and distance to agreement criteria of 3%/2 mm, compared to 95.7% in the previous formulation. This difference may be of clinical importance, as the new formulation may allow the quality assurance of complex treatment plans, relying on a variety of doses and dose rates; thus, expanding the potential practical application of the dosimeter.

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28

Kozicki, Marek, Malwina Jaszczak i Piotr Maras. "Features of PABIGnx 3D Polymer Gel as an Ionising Radiation Dosimeter". Materials 15, nr 7 (31.03.2022): 2550. http://dx.doi.org/10.3390/ma15072550.

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This work presents the features of the PABIGnx 3D polymer gel dosimeter. It consists of two cross-linkers: poly(ethylene glycol) diacrylate (PEGDA), as one biacrylic component, and N,N′-methylenebisacrylamide (MBA), which is another cross-linker often used in 3D dosimeters. Additionally, it contains oxygen scavenges of copper sulfate pentahydrate and ascorbic acid. All ingredients are embedded in a physical gel matrix of gelatine. Upon irradiation, the biacrylic cross-linking agents (PEGDA and MBA) undergo radical polymerisation and cross-linking, which is manifested by the appearance of the opacity of the intensity related to the absorbed dose. PABIGnx was irradiated with an oncological source of ionising radiation, and analysed by using a nuclear magnetic resonance (0.5 T). The following characteristics were obtained: (i) linear and dynamic dose-response of 0.5 to ~18 Gy and 40 Gy, respectively, (ii) dose sensitivity of 0.071 ± 0.001 Gy−1 s−1, (iii) integral 3D dose distribution for at least 24 days after irradiation, (iv) adequate batch-to-batch reproducibility, (v) dose-response independent of irradiation with 6 MV photons, 15 MV photons, 6 MV photons FFF of 0.0168–0.1094 Gy/s dose rates, and (vi) soft tissue equivalence. The study showed that the features of PABIGnx confirm its suitability for use in 3D radiotherapy dosimetry.

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29

Abraheem, Abeer Z., F. Khamis i Y. A. Abdulla. "TL Characteristics and Dosimetric Aspects of Mg-Doped ZnO". European Journal of Applied Physics 3, nr 1 (29.01.2021): 43–47. http://dx.doi.org/10.24018/ejphysics.2021.3.1.37.

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Dosimetry characterization and the evaluation of kinetics parameters of trapping states of Mg-doped ZnO phosphors synthesized by Sol-Gel technique. The thermoluminescence response of Mg-doped ZnO samples showed a linear response when exposed to X-ray radiation and the optimum annealing condition was 400oC/4h for the three concentrations. A broad-shaped TL glow curve with an upper bound of 270 °C, which shifts to lower temperatures with increasing dose, indicating that general order (GO) kinetics thermoluminescence processes are involved. We conclude that the ZnO doped Mg phosphors under study are promises to develop dosimeters for high radiation dose measurements. Kinetic parameters, such as activation energy (E), frequency factor (s), and order of kinematic order (b), were estimated by the Glow Curve Deconvolution (GCD) method. ZnO:Mg phosphor has a great potential as a dosimeter for monitoring in the fields of ionizing radiation.

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30

Einbergs, E., A. Zolotarjovs, I. Bite, J. Cipa, V. Vitola, K. Laganovska i L. Trinkler. "Re-Evaluation of Chromium Doped Alumina for Dosimetric Applications". Latvian Journal of Physics and Technical Sciences 58, nr 1 (29.01.2021): 15–22. http://dx.doi.org/10.2478/lpts-2021-0002.

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Abstract Many medical examinations involve ionizing radiation. Although the range of available dosimeters is rather wide, their linearity and chemical stability are limited. Recently, there has been a growing interest in new, improved dosimetric materials for emerging applications in medicine and other fields, such as sterilisation of consumer goods and medical instruments, irradiation of seeds, chemical agents and others. One of the classical dosimeters is carbon-doped alumina (Al2O3:C) – a well-established and widely used material for personal and industrial dosimeter with a range of great properties, such as high sensitivity, wide linearity range and relative ease of production and handling. However, the demand for reliable dosimeters in a high-dose range is still only partially fulfilled, and alumina doped with chromium ions (Al2O3:Cr) can be a promising candidate. In this study, we explored alumina doped with chromium porous microparticles synthesized with a sol-gel method as a possible high dose dosimeter and evaluated its thermostimulated luminescence signal, dose response with two irradiation sources and measured long-time fading. It was found that although the TSL signal was quite complex (consisting of two main peaks above room temperature) and the long-term fading was significant (around 50 % in the span of 30 days), with sufficient optimisation the material could be used as a high-dose dosimeter for X-ray and beta irradiation. Wide high dose linearity range, physical and chemical characteristics, as well as low production costs and ease of synthesis make chromium (III) doped alumina a compelling candidate for applicability in various medical and industry fields.

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31

Jordan, K. J., i K. H. Dekker. "Active heating of large gel dosimeters". Journal of Physics: Conference Series 847 (maj 2017): 012050. http://dx.doi.org/10.1088/1742-6596/847/1/012050.

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32

Deene, Y. De. "Essential characteristics of polymer gel dosimeters". Journal of Physics: Conference Series 3 (1.01.2004): 34–57. http://dx.doi.org/10.1088/1742-6596/3/1/006.

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Mather, Melissa L., Andrew K. Whittaker i Clive Baldock. "Ultrasound evaluation of polymer gel dosimeters". Physics in Medicine and Biology 47, nr 9 (19.04.2002): 1449–58. http://dx.doi.org/10.1088/0031-9155/47/9/302.

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Sellakumar, P., E. James Jebaseelan Samuel i Sanjay S. Supe. "Water equivalence of polymer gel dosimeters". Radiation Physics and Chemistry 76, nr 7 (lipiec 2007): 1108–15. http://dx.doi.org/10.1016/j.radphyschem.2007.03.003.

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35

Jirasek, A. "Experimental investigations of polymer gel dosimeters". Journal of Physics: Conference Series 56 (1.12.2006): 23–34. http://dx.doi.org/10.1088/1742-6596/56/1/003.

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Senden, Robert J., Paul De Jean, Kim B. McAuley i L. John Schreiner. "Polymer gel dosimeters with reduced toxicity". Journal of Physics: Conference Series 56 (1.12.2006): 156–59. http://dx.doi.org/10.1088/1742-6596/56/1/016.

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37

Whitney, Heather M., Daniel F. Gochberg i John C. Gore. "Magnetization transfer in polymer gel dosimeters". Journal of Physics: Conference Series 56 (1.12.2006): 253–55. http://dx.doi.org/10.1088/1742-6596/56/1/042.

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38

Mather, Melissa L., Anthony F. Collings, Nick Bajenov, Andrew K. Whittaker i Clive Baldock. "Ultrasonic absorption in polymer gel dosimeters". Ultrasonics 41, nr 7 (wrzesień 2003): 551–59. http://dx.doi.org/10.1016/s0041-624x(03)00153-7.

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39

Maeyama, Takuya, Nobuhisa Fukunishi, Kenichi L. Ishikawa, Kazuaki Fukasaku i Shigekazu Fukuda. "Radiological properties of nanocomposite Fricke gel dosimeters for heavy ion beams". Journal of Radiation Research 57, nr 3 (1.06.2016): 318–24. http://dx.doi.org/10.1093/jrr/rrw025.

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Abstract The radiological properties of nanocomposite Fricke gel (NC-FG) dosimeters prepared with different concentrations of nano-clay, perchloric acid and ferrous ions in deaerated conditions were investigated under carbon and argon ion beam irradiation covering a linear-energy-transfer (LET) range of 10 to 3000 eV/nm. We found that NC-FG exhibits radiological properties distinct from those of conventional Fricke gel. The radiation sensitivity of NC-FG is independent of the LET and is nearly constant even at very high LET (3000 eV/nm) values in the Bragg peak region of the argon ion beam. In addition, whereas conventional Fricke gel dosimeters only operate under acidic conditions, NC-FG dosimeters function under both acidic and neutral conditions. The radiation sensitivity decreases with decreasing nano-clay concentration in NC-FG, which indicates that the nano-clay plays a vital role in the radiation-induced oxidation of Fe 2+ .

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40

Penev, Kalin I., i Kibret Mequanint. "New directions for tetrazolium - gellan gum gel dosimeters". Journal of Physics: Conference Series 2167, nr 1 (1.01.2022): 012031. http://dx.doi.org/10.1088/1742-6596/2167/1/012031.

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Abstract Tetrazolium salt-based dosimeters are non-diffusing, gel dosimeters with excellent physical and chemical stability but with relatively low dose sensitivity and a dose rate dependence of the dose response. Both issues are tackled in this study by: (a) the introduction of a new tetrazolium salt with simple synthesis and dose response around 585 nm which may provide the pathway to more sensitive formulations and (b) producing gels with low gellan gum concentration, thus limiting the dose rate effects, and addition of thickening agents to restrain the liquid loss (syneresis) from the resulting gels.

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41

Jirasek, A., M. Hilts i K. B. McAuley. "Polymer gel dosimeters with enhanced sensitivity for use in x-ray CT polymer gel dosimetry". Physics in Medicine and Biology 55, nr 18 (18.08.2010): 5269–81. http://dx.doi.org/10.1088/0031-9155/55/18/002.

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42

Wong, C., W. Patterson, C. Powell, G. Qiao, D. Solomon i M. Geso. "SU-FF-T-188: Dosimetry of Microbeam Radiotherapy Using Gel Dosimeters". Medical Physics 34, nr 6Part10 (czerwiec 2007): 2444. http://dx.doi.org/10.1118/1.2760848.

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43

Oldham, M. "NEW DEVELOPMENTS IN 3D DOSIMETRY UTILIZING RADIOCHROMIC PLASTICS AND GEL-DOSIMETERS". Radiotherapy and Oncology 92 (sierpień 2009): S45—S46. http://dx.doi.org/10.1016/s0167-8140(12)72706-8.

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44

Murphy, P. S., V. P. Cosgrove, A. J. Schwarz, S. Webb i M. O. Leach. "Proton spectroscopic imaging of polyacrylamide gel dosimeters for absolute radiation dosimetry". Physics in Medicine and Biology 45, nr 4 (9.03.2000): 835–45. http://dx.doi.org/10.1088/0031-9155/45/4/302.

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45

ABDELRAHIM, M. S., KH M. HAROUN, A. H. ALFAKI, H. S. BUSH, O. ALDAGHRI i M. H. EISA. "EFFECTIVE ATOMIC NUMBERS AND ELECTRON DENSITIES OF GEL DOSIMETERS FOR He, B, C, AND O HIGHLY CHARGED PARTICLES INTERACTION IN THE ENERGY RANGE 10 keV–100 MeV". Digest Journal of Nanomaterials and Biostructures 16, nr 1 (styczeń 2021): 61–71. http://dx.doi.org/10.15251/djnb.2022.161.61.

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The radiological properties of different gel dosimeter formulations including six normoxic and four hypoxic polymeric gels, BRESAGE, PREAGE®, Fricke gel dosimeters, and water were investigated using SRIM code. The effective atomic number Zeff and electron density (Ne) for heavily charged particle interaction were calculated and performed for Helium (He), Boron (B), Carbon (C), and Oxygen (O) ion interactions in the energy range from 10 keV to 100 MeV. Variations of effective atomic number (Zeff) and electron density (Ne) with the kinetic energy of ions, (He, B, C, and O), were observed over the whole energy range for all studied materials. Variations of Zeff for He ion are up to 21%, 25%, and 20% for hypoxic and normoxic gels, Fricke gel, and PRESAGE gels, respectively. For other ions, variation is up to 34% for hypoxic and normoxic gels as well as Fricke gel, and 32% for PRESAGE gels. It is found that the maximum values of Zeff have been observed in intermediate energies between 1-10 MeV for all dosimeters, except for PRESAGE and PRESAGE® , where maximum values were observed in the relatively low energy range 10 – 100 keV. For effective atomic number relative to water, polymeric gels and Fricke gel showed better water equivalence with differences <7%, while PRESAGE and PRESAGE® showed high differences up to 17.5%, 22%, 21%, and 25% for He, B, C, and O ion, respectively. Gels found to be most relative to water are (Fricke, HEAG, and PAG), Fricke and HEAG), (Fricke and HEAG), and (Fricke, HEAG, and BANG-1) for He, B, C, and O ion interactions, respectively. Data reported here gives essential information about the interaction of different types of charged particles with different materials and could be useful in the energy range specified.

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46

ABDELRAHIM, M. S., KH M. HAROUN, A. H. ALFAKI, H. S. BUSH, O. ALDAGHRI i M. H. EISA. "EFFECTIVE ATOMIC NUMBERS AND ELECTRON DENSITIES OF GEL DOSIMETERS FOR He, B, C, AND O HIGHLY CHARGED PARTICLES INTERACTION IN THE ENERGY RANGE 10 keV–100 MeV". Digest Journal of Nanomaterials and Biostructures 16, nr 1 (styczeń 2021): 61–71. http://dx.doi.org/10.15251/djnb.2021.161.61.

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The radiological properties of different gel dosimeter formulations including six normoxic and four hypoxic polymeric gels, BRESAGE, PREAGE®, Fricke gel dosimeters, and water were investigated using SRIM code. The effective atomic number Zeff and electron density (Ne) for heavily charged particle interaction were calculated and performed for Helium (He), Boron (B), Carbon (C), and Oxygen (O) ion interactions in the energy range from 10 keV to 100 MeV. Variations of effective atomic number (Zeff) and electron density (Ne) with the kinetic energy of ions, (He, B, C, and O), were observed over the whole energy range for all studied materials. Variations of Zeff for He ion are up to 21%, 25%, and 20% for hypoxic and normoxic gels, Fricke gel, and PRESAGE gels, respectively. For other ions, variation is up to 34% for hypoxic and normoxic gels as well as Fricke gel, and 32% for PRESAGE gels. It is found that the maximum values of Zeff have been observed in intermediate energies between 1-10 MeV for all dosimeters, except for PRESAGE and PRESAGE® , where maximum values were observed in the relatively low energy range 10 – 100 keV. For effective atomic number relative to water, polymeric gels and Fricke gel showed better water equivalence with differences <7%, while PRESAGE and PRESAGE® showed high differences up to 17.5%, 22%, 21%, and 25% for He, B, C, and O ion, respectively. Gels found to be most relative to water are (Fricke, HEAG, and PAG), Fricke and HEAG), (Fricke and HEAG), and (Fricke, HEAG, and BANG-1) for He, B, C, and O ion interactions, respectively. Data reported here gives essential information about the interaction of different types of charged particles with different materials and could be useful in the energy range specified.

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47

Hurley, C., C. McLucas, G. Pedrazzini i C. Baldock. "High-resolution gel dosimetry of a HDR brachytherapy source using normoxic polymer gel dosimeters: Preliminary study". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 565, nr 2 (wrzesień 2006): 801–11. http://dx.doi.org/10.1016/j.nima.2006.05.167.

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48

Söderström, Daniel, Oskari Timonen, Heikki Kettunen, Risto Kronholm, Hicham El Hamzaoui, Bruno Capoen, Youcef Ouerdane i in. "Properties of Gd-Doped Sol-Gel Silica Glass Radioluminescence under Electron Beams". Sensors 22, nr 23 (28.11.2022): 9248. http://dx.doi.org/10.3390/s22239248.

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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.

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49

Venning, A. J., K. N. Nitschke, P. J. Keall i C. Baldock. "Radiological properties of normoxic polymer gel dosimeters". Medical Physics 32, nr 4 (23.03.2005): 1047–53. http://dx.doi.org/10.1118/1.1881812.

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50

Abtahi, Seyed Mohammad Mahdi, i Hamid Sadeghi Abandansari. "Polymer gel dosimeters with PVA–GA matrix". Australasian Physical & Engineering Sciences in Medicine 40, nr 3 (27.07.2017): 651–58. http://dx.doi.org/10.1007/s13246-017-0573-z.

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