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Artykuły w czasopismach na temat "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.
Rozprawy doktorskie na temat "Gel dosimeters"
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Wong, Christopher James, i chrisjwong@yahoo com au. "High Resolution Polymer Gel Dosimetry for Small and Micro Field Dosimetry, and Development of Innovative Polymer Gel Dosimeters". RMIT University. Medical Sciences, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091002.161512.
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Current radiotherapy techniques are focused on delivering effective treatments while sparing surrounding healthy tissues. As a result, radiotherapy treatments are using narrower and more tightly conforming therapy techniques. For these treatments to be effective an accurate measure of the dose delivered by these very narrow radiotherapy beams, both in and around the target volume, is required. It is a challenging task for the conventional type dosimeters to determine dose distribution in such small fields. The best example of such fields is microbeam beam radiotherapy (MRT), a developing treatment technique that takes this requirement even further. MRT delivers an array of micrometre size radiotherapy beams to the target. MRT has been shown to be highly effective, but reliable dosimetry of MRT is challenging due to the micrometre scales involved. Attempts to determine the MRT dose distribution have been documented for using special type dosimeters such as radioch romic film and MOSFET detectors, as well as Monte Carlo simulations. This thesis investigates polymer gels as a dosimeter for dose distribution measurements of small radiotherapy fields and microbeams. Polymer gel dosimetry is a technique which uses a tissue-equivalent gel to act as both a three-dimensional dosimeter and a phantom at the same time. These gels polymerise when exposed to ionising radiation and the response is locally dose dependent linearly. This thesis investigates the use of polymer gels for the dosimetry of small sub-centimetre (down to 3 × 3 mm2) and micrometre radiotherapy fields. A high resolution imaging technique is also required for such small beam dosimetry. This work used special high strength MRI scanners to analyse polymer gels at high resolution. This work explores the feasibility of polymer gels irradiated by microbeams and analysed using Raman spectroscopy as a dosimeter for synchrotron generated microbeams. MRT is characterised by very high doses, and special high-dose resistive types of gel were developed as part of this work. It is shown that polymer gels imagined using Raman spectroscopy techniques are capable of measuring the dose distribution of microbeam radiation techniques. This thesis also investigates the use of polymer gels to measure dose perturbations caused by metallic artefacts. Metallic artefacts, such as a surgical aneurysm clip, can be left in a patient and cause dose perturbations during radiotherapy procedures. Polymer gels were used to determine the degree of dose enhancement induced by an aneurysm clip placed inside when irradiated with a typical stereotactic radiotherapy procedure. In addition, this thesis used gels in several other innovative applications. Photonuclear interactions generated in gel by high energy x-ray beams were measured via secondary neutrons. Special clear-type gels that do not change colour with irradiation were developed. Polymer gels were investigated for dosimetry of an extremely high dose rate capacitor type linear accelerator. And polymer gels were for measurement of a high energy proton beam.
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Trapp, Jamie Vincent. "Imaging and radiation interactions of polymer gel dosimeters". Thesis, Queensland University of Technology, 2003. https://eprints.qut.edu.au/15904/1/Jamie_Trapp_Thesis.pdf.
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Aim: The past two decades have seen a large body of work dedicated to the development of a three dimensional gel dosimetry system for the recording of radiation dose distributions in radiation therapy. The purpose of much of the work to date has been to improve methods by which the absorbed dose information is extracted. Current techniques include magnetic resonance imaging (MRI), optical tomography, Raman spectroscopy, x-ray computed tomography (CT) and ultrasound. This work examines CT imaging as a method of evaluating polymer gel dosimeters. Apart from publications resulting from this work, there has been only two other journal articles to date reporting results of CT gel dosimetry. This indicates that there is still much work required to develop the technique. Therefore, the aim of this document is to develop CT gel dosimetry to the extent that it is of use to clinical and research physicists. Scope: Each chapter in this document describes an aspect of CT gel dosimetry which was examined; with Chapters 2 to 7 containing brief technical backgrounds for each aspect. Chapter 1 contains a brief review of gel dosimetry. The first step in the development of any method for reading a signal is to determine whether the signal can actually be obtained. However, before polymer gel dosimeters can be imaged using a CT scanner, imaging techniques are required which are employable to obtain reliable readings. Chapter 2 examines the various artifacts inherent in CT which interfere with the quantitative analysis of gel dosimeters and a method for their removal is developed. The method for artifact reduction is based on a subtraction technique employed previously in a feasibility study and a system is designed to greatly simplify the process. The simplification of the technique removes the requirement for accurate realignment of the phantom within the scanner and the imaging of calibration vials is enabled. Having established a method by which readings of polymer gel dosimeters can be obtained with CT, Chapter 3 examines the CT dose response. A number of formulations of polymer gel dosimeter are studied by varying the constituent chemicals and their concentrations. The results from this chapter can be employed to determine the concentration of chemicals when manufacturing a polymer gel dosimeter with a desired CT dose response. With the CT dose response characterised in Chapter 3, the macroscopic cause of the CT signal is examined in Chapter 4. To this end direct measurement of the linear attenuation coefficient is obtained with a collimated radiation source and detector. Density is measured by Archimedes' principle. Comparison of the two results shows that the cause of the CT signal is a density change and the implications for polymer gel dosimetry are discussed. The CT scanner is revisited in Chapter 5 to examine the CT imaging techniques required for optimal performance. The main limitation of the use of CT in gel dosimetry to date has been image noise. In Chapter 5 stochastic noise is investigated and reduced. The main source of non-stochastic noise in CT is found and imaging techniques are examined which can greatly reduce this residual noise. Predictions of computer simulations are verified experimentally. Although techniques for the reduction of noise are developed in Chapter 5, there may be situations where the noise must be further reduced. An image processing algorithm is designed in Chapter 6 which employs a combination of commonly available image filters. The algorithm and the filters are tested for their suitability in gel dosimetry through the use of a simulated dose distribution and by performing a pilot study on an irradiated polymer gel phantom. Having developed CT gel dosimetry to the point where a suitable image can be obtained, the final step is to investigate the uncertainty in the dose calibration. Methods used for calibration uncertainty in MRI gel dosimetry to date have either assumed a linear response up to a certain dose, or have removed the requirement for linearity but incorrectly ignored the reliability of the data and fit of the calibration function. In Chapter 7 a method for treatment of calibration data in CT gel dosimetry is proposed which allows for non-linearity of the calibration function, as well as the goodness of its fit to the data. Alternatively, it allows for the reversion to MRI techniques if linearity is assumed in a limited dose range. Conclusion: The combination of the techniques developed in this project and the newly formulated normoxic gels (not extensively studied here) means that gel dosimetry is close to becoming viable for use in the clinic. The only capital purchase required for a typical clinic is a suitable water tank, which is easily and inexpensively producible if the clinic has access to a workshop.
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Trapp, Jamie Vincent. "Imaging And Radiation Interactions Of Polymer Gel Dosimeters". Queensland University of Technology, 2003. http://eprints.qut.edu.au/15904/.
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Aim: The past two decades have seen a large body of work dedicated to the development of a three dimensional gel dosimetry system for the recording of radiation dose distributions in radiation therapy. The purpose of much of the work to date has been to improve methods by which the absorbed dose information is extracted. Current techniques include magnetic resonance imaging (MRI), optical tomography, Raman spectroscopy, x-ray computed tomography (CT) and ultrasound. This work examines CT imaging as a method of evaluating polymer gel dosimeters. Apart from publications resulting from this work, there has been only two other journal articles to date reporting results of CT gel dosimetry. This indicates that there is still much work required to develop the technique. Therefore, the aim of this document is to develop CT gel dosimetry to the extent that it is of use to clinical and research physicists. Scope: Each chapter in this document describes an aspect of CT gel dosimetry which was examined; with Chapters 2 to 7 containing brief technical backgrounds for each aspect. Chapter 1 contains a brief review of gel dosimetry. The first step in the development of any method for reading a signal is to determine whether the signal can actually be obtained. However, before polymer gel dosimeters can be imaged using a CT scanner, imaging techniques are required which are employable to obtain reliable readings. Chapter 2 examines the various artifacts inherent in CT which interfere with the quantitative analysis of gel dosimeters and a method for their removal is developed. The method for artifact reduction is based on a subtraction technique employed previously in a feasibility study and a system is designed to greatly simplify the process. The simplification of the technique removes the requirement for accurate realignment of the phantom within the scanner and the imaging of calibration vials is enabled. Having established a method by which readings of polymer gel dosimeters can be obtained with CT, Chapter 3 examines the CT dose response. A number of formulations of polymer gel dosimeter are studied by varying the constituent chemicals and their concentrations. The results from this chapter can be employed to determine the concentration of chemicals when manufacturing a polymer gel dosimeter with a desired CT dose response. With the CT dose response characterised in Chapter 3, the macroscopic cause of the CT signal is examined in Chapter 4. To this end direct measurement of the linear attenuation coefficient is obtained with a collimated radiation source and detector. Density is measured by Archimedes' principle. Comparison of the two results shows that the cause of the CT signal is a density change and the implications for polymer gel dosimetry are discussed. The CT scanner is revisited in Chapter 5 to examine the CT imaging techniques required for optimal performance. The main limitation of the use of CT in gel dosimetry to date has been image noise. In Chapter 5 stochastic noise is investigated and reduced. The main source of non-stochastic noise in CT is found and imaging techniques are examined which can greatly reduce this residual noise. Predictions of computer simulations are verified experimentally. Although techniques for the reduction of noise are developed in Chapter 5, there may be situations where the noise must be further reduced. An image processing algorithm is designed in Chapter 6 which employs a combination of commonly available image filters. The algorithm and the filters are tested for their suitability in gel dosimetry through the use of a simulated dose distribution and by performing a pilot study on an irradiated polymer gel phantom. Having developed CT gel dosimetry to the point where a suitable image can be obtained, the final step is to investigate the uncertainty in the dose calibration. Methods used for calibration uncertainty in MRI gel dosimetry to date have either assumed a linear response up to a certain dose, or have removed the requirement for linearity but incorrectly ignored the reliability of the data and fit of the calibration function. In Chapter 7 a method for treatment of calibration data in CT gel dosimetry is proposed which allows for non-linearity of the calibration function, as well as the goodness of its fit to the data. Alternatively, it allows for the reversion to MRI techniques if linearity is assumed in a limited dose range. Conclusion: The combination of the techniques developed in this project and the newly formulated normoxic gels (not extensively studied here) means that gel dosimetry is close to becoming viable for use in the clinic. The only capital purchase required for a typical clinic is a suitable water tank, which is easily and inexpensively producible if the clinic has access to a workshop.
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Sedaghat, Mahbod. "A study on radiochemical errors in polymer gel dosimeters". Thèse, Université de Sherbrooke, 2012. http://hdl.handle.net/11143/6252.
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À ce jour, les seul dosimètres purement tridimensionnels (3D) sont basés sur la détection d’une propriété physique résultant d’une série de réactions chimiques radio-induites dans un volume de gel ou de plastique. Les études initiales ont généré beaucoup d’enthousiasme mais ces dosimètres 3D ne sont pas parvenus à une utilisation répandue dans les départements de radio-oncologie pour l’assurance-qualité 3D et la vérification de traitements complexes de radiothérapie moderne. Le temps et la complexité de la préparation de ces dosimètres 3D ne sont pas les raisons principales qui empêchent leur déploiement clinique. Ce sont plutôt leurs performances et la reproductibilité des mesures qui doivent être améliorées. Les plus étudiés et les plus utilisés parmi les différents types de dosimètres 3D sont les dosimètres à gels de polymère. De nombreuses compositions chimiques ont été proposées et testées pour la dosimétrie à gels de polymère. L’utilisation d’un antioxydant s’est révélée une découverte majeure dans le domaine puisque l’oxygène interfère avec le mécanisme de réponse des gels. Pourtant, un nombre croissant d’erreurs inexpliquées ont été rapportées dans les écrits et ont soulevé un doute sur la reproductibilité et la justesse des doses déterminées avec ces gels. Cette thèse a été entreprise pour étudier les sources radiochimiques d’erreurs dans les dosimètres à gels de polymère. Il était admis dans les écrits que l’utilisation d’un antioxydant permettait de contoumer tous les effets non-désirés de l’oxygène. Cette thèse démontre que cela était faux. Une méthodologie a été développée pour isoler l’effet de l’oxygène dans un gel de polymère contenant ou non un antioxydant. Les résultats ont révélé que la présence conjointe d’oxygène et d’antioxydant modifie la réponse du dosimètre. Indépendamment de la composition du dosimètre et de l’antioxydant, cet effet peut induire des erreurs dosimétriques significatives dans des mesures simples et dont les origines étaient difficilement appréciables en ignorant l’effet de l'oxygène et de l’antioxydant. Nos résultats nous permettent de postuler les réactions dominantes des antioxydants étudiés et leur devenir chimique au sein d’un gel de polymère sous irradiation. Puisque l’effet de l’oxygène et de l’antioxydant était négligé, plusieurs autres facteurs physico-chimiques faisaient l’objet d’hypothèse pour expliquer les erreurs observées. Ces facteurs incluent la compression des gels et des variations de propagation et de terminaison de la polymérisation reliées à la chaleur générée pendant la polymérisation. Des études détaillées de ces effets nous permettent de refuter ces hypothèses. Nos résultats nous permettent d’analyser, de catégoriser et de proposer des explications sur l’origine des erreurs dosimétriques recensées dans les écrits. Finalement, l’effet d’un antioxydant en particulier, le chlorure de tetrakis-(hydroxyméthyle) phosphonium (THPC), a été étudié en relation avec la structure du polymère formé dans un gel de polymère basé sur l’acrylamide. Le THPC est l’antioxydant le plus utilisé dans les différents dosimètres à gels de polymère. La spectroscopie FT-Raman et la microscopie électronique ont révélé que le THPC réagit avec les monomères pendant la polymérisation. Notre interprétation suggère un rôle important du THPC dans les variations de réponse à la dose dans les gels de polymère. La conclusion générale de cette thèse est que l’élimination chimique de l'oxygène par un antioxydant facilite grandement la préparation des dosimètres mais leur performance en est grandement altérée en comparaison avec des préparations dites anoxiques. L’oxygène demeure une source majeure d’erreur dans les dosimètres à gels de polymère.
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Hurley, Christopher Anthony. "The development of normoxic polymer gel dosimetry using high resolution MRI". Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16442/1/Christopher_Hurley_Thesis.pdf.
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Dosimetry is a vital component of treatment planning in radiation therapy. Methods of radiation dosimetry currently include the use of: ionization chambers, thermoluminescent dosimeters (TLDs), solid-state detectors and radiographic film. However, these methods are inherently either 1D or 2D and their use involves the perturbation of the radiation beam. Although the dose distribution within tissues following radiation therapy treatments can be modeled using computerized treatment planning systems, a need exists for a dosimeter that can accurately measure dose distributions directly and produce 3D dose maps. Some radiation therapy and brachytherapy treatments require mapping the dose distributions in high-resolution (typically < 1 mm). A dosimetry technique that is capable of producing high resolution 3D dose maps of the absorbed dose distribution within tissues is required.
Gel dosimetry is inherently a 3D integrating dosimeter that offers high spatial resolution, precision and accuracy. Polymer gel dosimetry is founded on the basis that monomers dissolved in the gel matrix polymerize due to the presence of free radicals produced by the radiolysis of water molecules. The amount of polymerization that occurs within a polymer gel dosimeter can be correlated to the absorbed dose. The gel matrix maintains the spatial integrity of the polymers and hence a dose distribution can be determined by imaging the irradiated polymer gel dosimeter using an imaging modality such as MRI, x-ray computed tomography (CT), ultrasound, optical CT or vibrational spectroscopy. Polymer gel dosimeters, however, suffer from oxygen contamination. Oxygen inhibits the polymerization reaction and hence polymer gel dosimeters must be manufactured, irradiated and scanned in hypoxic environments.
Normoxic polymer gel dosimeters incorporate an anti-oxidant into the formulation that binds the oxygen present in the gel and allows the dosimeter to be made under normal atmospheric conditions. The first part of this study was to provide a comprehensive investigation into various formulations of polymer and normoxic polymer gel dosimeters. Several parameters were used to characterize and assess the performance of each formulation of polymer gel dosimeter including: spatial resolution and stability, temporal stability of the R2-dose response, optimal R2-dose response for changes in concentration of constituents and the effects of oxygen infiltration. This work enabled optimal formulations to be determined that would provide greater dose sensitivity. Further work was done to investigate the chemical kinetics that take place within normoxic polymer gel dosimeters from manufacture to post-irradiation. This study explored the functions that each of the constituent chemicals plays in a polymer gel dosimeter. Although normoxic polymer gel dosimeters exhibit very similar characteristics to polyacrylamide polymer gel dosimeters, one important difference between them was found to be a decrease in R2-dose sensitivity over time in the normoxic polymer gel dosimeter compared to an increase in the polyacrylamide polymer gel dosimeters.
From an investigation into the function of anti-oxidants in normoxic polymer gel dosimeters, alternatives were proposed. Several alternative anti-oxidants were explored in this study that found that whilst some were reasonably effective, tetrakis (hydroxymethyl) phosphonium chloride (THPC) had the highest reaction rate. THPC was found not only to be an aggressive scavenger of oxygen, but also to increase the dose sensitivity of the gel. Hence, a formulation of normoxic polymer gel dosimeter was proposed, called MAGAT, that comprised: methacrylic acid, gelatin, hydroquinone and THPC. This formulation was examined in a similar fashion to the studies of the other formulations of polymer and normoxic polymer gel dosiemeters. The gel was found to exhibit spatial and temporal stability and an optimal formulation was proposed based on the R2-dose response.
Applications such as IVBT require high-resolution dosimetry. Combined with high-resolution MRI, polymer gel dosimetry has potential as a high-resolution 3D integrated dosimeter. Thus, the second component of this study was to commission a micro-imaging MR spectrometer for use with normoxic polymer gel dosimeters and investigate artifacts related to imaging in high-resolutions. Using high-resolution MRI requires high gradient strengths that, combined with the Brownian motion of water molecules, was found to produce an attenuation of the MR signal and hence lead to a variation in the measured R2. The variation in measured R2 was found to be dependent on both the timing and amplitude of pulses in the pulse sequence used during scanning. Software was designed and coded that could accurately determine the amount of variation in measured R2 based on the pulse sequence applied to a phantom. Using this software, it is possible to correct for differences between scans using different imaging parameters or pulse sequences.
A normoxic polymer gel dosimeter was irradiated using typical brachytherapy delivery and the resulting dose distributions compared with dose points predicted by the computerized treatment planning system.The R2-dose response was determined and used to convert the R2 maps of the phantoms to dose maps. The phantoms and calibration vials were imaged with an in-plane resolution of 0.1055 mm/pixel and a slice thickness of 2 mm. With such a relatively large slice thickness compared to the in-plane resolution, partial volume effects were significant, especially in the region immediately adjacent the source where high dose gradients typically exist. Estimates of the partial volume effects at various distances within the phantom were determined using a mathematical model based on dose points from the treatment planning system. The normalized and adjusted dose profiles showed very good agreement with the dose points predicted by the treatment planning system.
6
Hurley, Christopher Anthony. "The development of normoxic polymer gel dosimetry using high resolution MRI". Queensland University of Technology, 2006. http://eprints.qut.edu.au/16442/.
Pełny tekst źródłaStreszczenie:
Dosimetry is a vital component of treatment planning in radiation therapy. Methods of radiation dosimetry currently include the use of: ionization chambers, thermoluminescent dosimeters (TLDs), solid-state detectors and radiographic film. However, these methods are inherently either 1D or 2D and their use involves the perturbation of the radiation beam. Although the dose distribution within tissues following radiation therapy treatments can be modeled using computerized treatment planning systems, a need exists for a dosimeter that can accurately measure dose distributions directly and produce 3D dose maps. Some radiation therapy and brachytherapy treatments require mapping the dose distributions in high-resolution (typically < 1 mm). A dosimetry technique that is capable of producing high resolution 3D dose maps of the absorbed dose distribution within tissues is required. Gel dosimetry is inherently a 3D integrating dosimeter that offers high spatial resolution, precision and accuracy. Polymer gel dosimetry is founded on the basis that monomers dissolved in the gel matrix polymerize due to the presence of free radicals produced by the radiolysis of water molecules. The amount of polymerization that occurs within a polymer gel dosimeter can be correlated to the absorbed dose. The gel matrix maintains the spatial integrity of the polymers and hence a dose distribution can be determined by imaging the irradiated polymer gel dosimeter using an imaging modality such as MRI, x-ray computed tomography (CT), ultrasound, optical CT or vibrational spectroscopy. Polymer gel dosimeters, however, suffer from oxygen contamination. Oxygen inhibits the polymerization reaction and hence polymer gel dosimeters must be manufactured, irradiated and scanned in hypoxic environments. Normoxic polymer gel dosimeters incorporate an anti-oxidant into the formulation that binds the oxygen present in the gel and allows the dosimeter to be made under normal atmospheric conditions. The first part of this study was to provide a comprehensive investigation into various formulations of polymer and normoxic polymer gel dosimeters. Several parameters were used to characterize and assess the performance of each formulation of polymer gel dosimeter including: spatial resolution and stability, temporal stability of the R2-dose response, optimal R2-dose response for changes in concentration of constituents and the effects of oxygen infiltration. This work enabled optimal formulations to be determined that would provide greater dose sensitivity. Further work was done to investigate the chemical kinetics that take place within normoxic polymer gel dosimeters from manufacture to post-irradiation. This study explored the functions that each of the constituent chemicals plays in a polymer gel dosimeter. Although normoxic polymer gel dosimeters exhibit very similar characteristics to polyacrylamide polymer gel dosimeters, one important difference between them was found to be a decrease in R2-dose sensitivity over time in the normoxic polymer gel dosimeter compared to an increase in the polyacrylamide polymer gel dosimeters. From an investigation into the function of anti-oxidants in normoxic polymer gel dosimeters, alternatives were proposed. Several alternative anti-oxidants were explored in this study that found that whilst some were reasonably effective, tetrakis (hydroxymethyl) phosphonium chloride (THPC) had the highest reaction rate. THPC was found not only to be an aggressive scavenger of oxygen, but also to increase the dose sensitivity of the gel. Hence, a formulation of normoxic polymer gel dosimeter was proposed, called MAGAT, that comprised: methacrylic acid, gelatin, hydroquinone and THPC. This formulation was examined in a similar fashion to the studies of the other formulations of polymer and normoxic polymer gel dosiemeters. The gel was found to exhibit spatial and temporal stability and an optimal formulation was proposed based on the R2-dose response. Applications such as IVBT require high-resolution dosimetry. Combined with high-resolution MRI, polymer gel dosimetry has potential as a high-resolution 3D integrated dosimeter. Thus, the second component of this study was to commission a micro-imaging MR spectrometer for use with normoxic polymer gel dosimeters and investigate artifacts related to imaging in high-resolutions. Using high-resolution MRI requires high gradient strengths that, combined with the Brownian motion of water molecules, was found to produce an attenuation of the MR signal and hence lead to a variation in the measured R2. The variation in measured R2 was found to be dependent on both the timing and amplitude of pulses in the pulse sequence used during scanning. Software was designed and coded that could accurately determine the amount of variation in measured R2 based on the pulse sequence applied to a phantom. Using this software, it is possible to correct for differences between scans using different imaging parameters or pulse sequences. A normoxic polymer gel dosimeter was irradiated using typical brachytherapy delivery and the resulting dose distributions compared with dose points predicted by the computerized treatment planning system.The R2-dose response was determined and used to convert the R2 maps of the phantoms to dose maps. The phantoms and calibration vials were imaged with an in-plane resolution of 0.1055 mm/pixel and a slice thickness of 2 mm. With such a relatively large slice thickness compared to the in-plane resolution, partial volume effects were significant, especially in the region immediately adjacent the source where high dose gradients typically exist. Estimates of the partial volume effects at various distances within the phantom were determined using a mathematical model based on dose points from the treatment planning system. The normalized and adjusted dose profiles showed very good agreement with the dose points predicted by the treatment planning system.
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Tudela, Diego Renan Giglioti. "Estudo da luminescência de cristais de quartzo naturais e artificiais crescidos pelo método sol-gel". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-08032019-090623/.
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Este trabalho foi dividido em duas grandes partes principais, a primeira relacionada ao estudo da luminescência de quatro espécimes de quartzo naturais brasileiros (verde, hialino, rosa e azul) e a segunda trata da confecção e caracterização de amostras sintéticas, baseadas na estrutura do SiO2, obtidas pelo método de sol-gel para fins de dosimetria das radiações ionizantes ambientais. Através da Análise por Ativação com Nêutrons Instrumental (AANI) e Fluorescência de Raios X por Reflexão Total (TXRF), foram determinadas as principais impurezas em concentrações maiores, menores e traços de forma quantitativa e qualitativa, respectivamente. Os espécimes verde e azul foram os que apresentaram as maiores quantidades de impurezas, incluindo metais e elementos terras raras, enquanto que o hialino e rosa são praticamente puros. Suas emissões de TL foram distintas, em termos de intensidade e posição dos picos. Testes de recuperação de dose por luminescência opticamente estimulada (LOE), através dos protocolos de alíquotas múltiplas (MAR) e única (SAR) com doses regenerativas, foram realizados e o espécime verde foi o único que apresentou resultados satisfatórios nesses testes, seguido do azul. Os cristais hialino e rosa apresentaram saturação e curva de crescimento fora da linearidade, onde o primeiro mostrou o efeito da fototransferência para a maioria das análises de SAR. Como os cristais verde e hialino apresentaram resultados opostos, em termos de quantidades de impurezas e emissões luminescentes, foi realizado um tratamento térmico em alta temperatura (1600 °C) para observar o efeito da mudança de fase (cristobalita) nas suas emissões luminescente. Ajustes teóricos das curvas de emissão de LOE contínua, linearmente modulada e TL mostraram que elas seguem o modelo teórico de cinéticas de ordens gerais. Na segunda parte deste trabalho, 32 amostras artificiais, do polimorfo de alta temperatura do quartzo, a cristobalita, foram sintetizadas com diferentes quantidades e tipos de dopantes, baseado nas impurezas determinadas no quartzo verde, utilizando duas rampas de aquecimento nas calcinações (3 e 15 °C/min). Essa parte do trabalho teve como finalidade o estudo do efeito do Fe na emissão luminescente das amostras sintéticas, a reprodução de uma das amostras naturais e produção e caracterização de dosímetros para radiações ionizantes ambientais. A utilização das duas rampas de aquecimento na emissão de TL, de forma geral, não desempenhou papel determinante na intensidade dos picos de altas temperaturas. Já na LOE foi observado que as amostras calcinadas com a rampa de maior temperatura apresentaram resposta à dose mais elevadas. O Fe como dopante em maior quantidade atuou como um inibidor de luminescência tanto na TL quanto na LOE. Uma amostra com características qualitativas semelhante ao quartzo verde, na fase da cristobalita, foi obtida com relativo sucesso utilizando como dopante todas as doze principais impurezas adquiridas para realização deste projeto. Quatro amostras foram sintetizadas com diferentes tipos e quantidades de dopantes para aplicação em dosimetria das radiações. Somente uma destas apresentou resposta linear às doses de radiação utilizando estimulação térmica (TL), cuja mínima dose de detecção (MDD) foi de 172 µGy. Utilizando estimulação óptica (LOE), duas amostras apresentaram comportamento linear com as doses de radiação, em que valores de MDD de ~440 µGy e 405 µGy foram obtidos.This work was divided into two major parts, the first one related to the study of the luminescence of four Brazilian natural quartz specimens (green, hyaline, pink and blue) and the second one deals with the confection and characterization of synthetic samples, based on SiO2 structure, obtained by means of sol-gel method to environmental ionizing radiation dosimetry. Through Instrumental Neutron Activation Analysis (INAA) and Total Reflection X-ray Fluorescence (TXRF), the main impurities in major, minor and trace concentrations were determined quantitative and qualitatively respectively. The green and blue specimens presented the highest amounts of impurities, including metals and rare earth elements, whereas hyaline and pink are practically pure. Their TL emissions were distinct, in terms of intensity and peak position. OSL dose recovery tests, using multiple (MAR) and single aliquots regeneration (SAR) dose protocols were performed and the green specimen was the only one which presented satisfactory results in these tests, followed by blue. The hyaline and pink crystals showed saturation and growth curve out of linearity, where the first one showed the effect of phototransference for most SAR analysis. As green and hyaline crystals presented opposite results, in terms of impurities quantities and luminescent emissions, a high temperature (1600 °C) heat treatment was performed to observe the effect of the phase change (cristobalite) on its luminescent emissions. Theoretical adjustments of the CW-OSL, LM-OSL and TL emission curves showed that they follow the theoretical model of general order kinetics. In the second part of this work, 32 artificial samples of the high temperature polymorph of the quartz, cristobalite, were synthesized with different amounts and types of dopants, based on impurities determined in green quartz, making use of two heating rates in the calcinations (3 and 15 °C/min). This part of the work had as purpose the study of the effect of Fe in the luminescent emission of the synthetic samples, the reproduction of one of the natural samples and production and characterization of dosimeters for environmental ionizing radiation. The use of the two heating rates in TL emission, in general, did not play a determining role in the intensity of the high temperature peaks. In the OSL, it was observed that samples calcined with higher heating rate temperature showed higher response to dose. The Fe as a dopant in greater quantities acted as a quencher of luminescence both in TL and OSL. A sample with qualitative characteristics similar to the green quartz, in the cristobalite phase, was obtained with relative success using as dopants all the twelve main impurities acquired for this project. Four samples were synthesized with different types and amounts of dopants for application in ionizing radiation dosimetry. Only one of these showed a linear response to radiation doses using thermal stimulation (TL), with a minimum detectable dose (MDD) of 172 µGy. Using optical stimulation (OSL), two samples showed linear behavior with radiation doses, in which MDD values of ~440 µGy and 405 µGy were obtained.
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Mizuno, Erick Yukio. "Desenvolvimento e caracterização de um gel de alanina para aplicação na medida da distribuição da dose de radiação usando a técnica de espectrofotometria". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-16052012-110041/.
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Este trabalho tem por objetivo a composição e caracterização de um dosímetro à base de DL-Alanina e Ferro-ll em forma de gel para aplicações em dosimetría para campos de doses da radiação gama do Co-60 experimentadas em procedimentos de radioterapia. O aminoácido DL-Alanina é dissolvido em solução ácida contendo o Fe-ll e adicionado o gel. Procedeu-se a uma série de ensaios variando reagente a reagente e realizando procedimentos para avaliar o comportamento em função do tempo do gel dosimétrico obtido. Os espectros de absorção antes e após a irradiação apresentam máximos em 457 nm e 588 nm, respectivamente. Esses dois picos correspondem aos comprimentos de onda de absorção das espécies Fe-ll e Fe-lll, respectivamente; estando ambas as espécies em equilíbrio. Com a irradiação, ocorre a formação de radicais que oxidam o Fe-ll em Fe-lll, alterando com isso o balanço entre as duas espécies - daí o aumento da concentração de Fe-lll - fazendo com que mude a tonalidade do gel, sendo, portanto, possível de ser determinada a dose absorvida. Nas análises dos espectros e respectivas curvas dose-resposta observou-se que o gel dosimétrico apresenta linearidade no intervalo de doses entre 0,5 e 40 Gy. A partir dos resultados obtidos de linearidade, estabilidade e menor dose detectável - 0,3 Gy - conclui-se que o presente Gel Dosimétrico à base de DL-Alanina e Fe-ll apresenta excelente potencial para a finalidade que é proposto, qual seja a determinação do campo de doses em radioterapia e futura aplicação como padrão na determinação desses campos, em 3D, utilizando-se a técnica de Imagem por Ressonância Magnética - IRM.The aim of this work is to develop a DL-Alanine, Fe-ll based gel dosimeter to be applied in the dosimetry of the Co-60 gamma-radiation fields in the dose range of radiation therapy procedures. The aminoacid DL-Alanine is dissolved in an acid solution containing the Fe-ll and added to the gel. A series of essays was performed with different chemicals and different procedures were made to evaluate the behavior of the obtained dosimetric gel as function of the time. The absorption spectra, before and after the irradiation, present maximum in 457 nm and 588 nm, respectively. These two peaks correspond to absorption wavelengths of the chemical species Fe-ll and Fe-lll, respectively, both species being in equilibrium. With the irradiation, the formation of the radicals that oxide the Fe-ll into Fe-lll occurs, altering the chemical balance of both species - hence the increase of the Fe-lll - and causing the gel to change its tonality, in such a way that it is possible to determine the absorved dose. In the analysis of the spectra and respective dose-response curves it was observed that the dosimetric gel shows linearity in dose range of 0.5 to 40 Gy. From the obtained linearity results, stability and lower detectable dose - 0,3 Gy - it is possible to conclude that the present DL-Alanine, Fe-ll based dosimetric gel presents an excellent potential to the application to which it is proposed, namely, the determination of the dose fields in radiation therapy and its future application as a standard in the determination of these fields, in 3D, using the Magnetic Resonance Imaging.
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CAPELETI, FELIPE F. "Dosimetria em tomografia computadorizada e avaliação do perfil de dose empregando dosímetro fricke gel e a técnica de imageamento por ressonância magnética". reponame:Repositório Institucional do IPEN, 2014. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11789.
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Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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CAVINATO, CHRISTIANNE C. "Padronizacao do metodo de dosimetria fricke gel e avaliacao tridimensional de dose empregando a tecnica de imageamento por ressonancia magnetica". reponame:Repositório Institucional do IPEN, 2009. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9406.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
Części książek na temat "Gel dosimeters"
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Campbell, W. G., D. M. Wells i A. Jirasek. "Destructive backscatter-based readout of polymer gel dosimeters: proof of principle". W IFMBE Proceedings, 629–32. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-19387-8_153.
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Oldham, Mark, Jeffrey H. Siewerdsen i David A. Jaffray. "An initial investigation of Optical CT and MR scanning of gel dosimeters". W The Use of Computers in Radiation Therapy, 383–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-642-59758-9_145.
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De Deene, Yves. "Polymer Gel Dosimetry". W Clinical 3D Dosimetry in Modern Radiation Therapy, 99–136. Boca Raton : Taylor & Francis, 2017. | Series: Imaging in medical diagnosis and therapy ; 28: CRC Press, 2017. http://dx.doi.org/10.1201/9781315118826-5.
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Ravindran, Paul B. "Small Photon Field Dosimetry using Gel". W IFMBE Proceedings, 762–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03474-9_215.
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Scheib, S. G., i W. Vogelsanger. "MAGIC - Normoxic Polymer Gel Dosimetry in Radiosurgery". W Radiosurgery, 213–24. Basel: KARGER, 2004. http://dx.doi.org/10.1159/000078121.
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Titus, Deena, E. James Jebaseelan Samuel i Selvaraj Mohana Roopan. "Radiation Dosimetry—A Different Perspective of Polymer Gel". W Polymer Gels, 309–41. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-6086-1_8.
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Abtahi, S. M., S. M. Aghamiri, H. Khalafi i M. Zahmatkesh. "Thermal neutron dose evaluation using MAGICA polymer gel dosimeter". W IFMBE Proceedings, 1157–59. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-29305-4_303.
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Kang, Young-nam, Jisun Jang, Byung-Ock Choi, Hong-Suk Jang, Ji-Young Jung, Hun-Joo Shin, Jae-Hyuk Seo, Ihl-Bohng Choi, Dong-Joon Lee i Soo-Il Kwon. "BANG-3® polymer gel dosimetry in Cyberknife". W IFMBE Proceedings, 683–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-03474-9_192.
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Maeyama, T., N. Fukunishi, K. L. Ishikawa, K. Fukasaku, T. Furuta, S. Takagi, S. Noda i R. Himeno. "Diffusion suppression in gel dosimetry by addition of nanoclay". W IFMBE Proceedings, 1183–86. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-29305-4_310.
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Cosgrove, Vivian P., David J. Convery, Philip S. Murphy, Christopher M. Nutting i Steve Webb. "Dynamic MLC delivered IMRT: verification using Polyacrylamide gel dosimetry". W The Use of Computers in Radiation Therapy, 311–13. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-642-59758-9_118.
Pełny tekst źródłaStreszczenia konferencji na temat "Gel dosimeters"
1
Gambarini, G., G. M. Liosi, E. Artuso, F. Giacobbo, M. Mariani, L. Brambilla, C. Castiglioni, M. Carrara i E. Pignoli. "Study of the absorption spectra of Fricke xylenol orange gel dosimeters". W 2015 4th International Conference on Advancements in Nuclear Instrumentation Measurement Methods and their Applications (ANIMMA). IEEE, 2015. http://dx.doi.org/10.1109/animma.2015.7465579.
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Manjappa, Rakesh, Sharath M. Shankaranarayana, Rajesh Kumar, Ram Mohan Vasu i Rajan Kanhirodan. "Correction of refraction distortion due to boundary mismatch in optical ct of gel dosimeters". W Cancer Imaging and Therapy. Washington, D.C.: OSA, 2016. http://dx.doi.org/10.1364/cancer.2016.jw3a.2.
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Gambarini, Grazia, Emanuele Artuso, Marco Felisi, Giorgio Colombo, Dario Giove, Stefano Agosteo, Andrea Pola i in. "Gel dosimeters for dose imaging in high fluences of epithermal neutrons: Potentiality and limitations". W 2015 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC). IEEE, 2015. http://dx.doi.org/10.1109/nssmic.2015.7581905.
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Aoki, Yutaro, Glenn Harvel, Toshiharu Sakura i Takeyoshi Sunagawa. "Development of a Gel Type Dosimeter for X-Ray Fields". W 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-67618.
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In recent years, use of radiation beams or particle beams have been put to practical use for cancer therapy. In cancer radiation therapy, visualization of radiation patterns is absolutely necessary for precisely evaluating the dose distribution. Therefore, gel type or Fricke type dosimeters [1] are considered useful for visualization. In this study, we developed a new type of gel dosimeter using a doped polyvinyl alcohol (PVA) based solution. This gel uses a red color based chemical reaction that occurs when the active agent is separated. Irradiation of the gel with X-rays is sufficient to break the chemical bonds of the active agent. We irradiated different gel samples with X-rays from a Hitachi MBR-1520R-3 source under different configurations to test the gel performance. We used UV-VIS spectrometry to measure the absorbance of transmitted light through the gel. For the active agent, the absorbance is at a peak wavelength of 490 nm. The amount of absorbance is proportional to the number of interactions with X-rays. We irradiated the gel between 0.5Gy-10Gy with visualization of the gel by photography and spectrometry between each irradiation. The spectrometry was performed using a StellarNet Black Comet system observing the absorbance between 300nm and 600nm. The results show that as the X-ray dose increases, the gel transitions from a clear gel to a light pink gel and then to a red gel. All colors are translucent and allow for the passage of light. The first samples were done in clear plastic containers of 250 ml size. The containers were filled with gel to eliminate air and possible oxygen contamination. The second set of experiments repeated the first study but used metallic coins as X-ray shields. The regions covered by the coins were protected from the dose and remained clear. A sharp edge was observed at the edge of the coin. This implies that the gel does not diffuse and hence can represent a dose distribution as long as it is not mixed. The third samples were placed in disposable cells for measurement of absorbance. The absorbance had a peak in the vicinity wavelength of 490nm. The results confirmed the absorbance to be proportional for increasing applied dose. In summary, a color transition gel was developed for use in detecting irradiation dose from X-rays. This technique has potential application for visualization of dose during medical procedures.
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CARRARA, M., S. TOMATIS, G. ZONCA, G. GAMBARINI, G. BARTESAGHI, C. TENCONI, A. CERROTTA i C. FALLAI. "FRICKE GEL DOSIMETERS FOR THE MEASUREMENT OF THE ANISOTROPY FUNCTION OF A HDR IR-192 BRACHYTHERAPY SOURCE". W Proceedings of the 11th Conference. WORLD SCIENTIFIC, 2010. http://dx.doi.org/10.1142/9789814307529_0100.
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Taylor, M. L., R. D. Franich, J. V. Trapp i P. N. Johnston. "A comparative study of the effect of calibration conditions on the water equivalence of a range of gel dosimeters". W 2007 IEEE Nuclear Science Symposium Conference Record. IEEE, 2007. http://dx.doi.org/10.1109/nssmic.2007.4436800.
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Janzen, Ryan, i Steve Mann. "Veillance dosimeter, inspired by body-worn radiation dosimeters, to measure exposure to inverse light". W 2014 IEEE Games, Media, Entertainment (GEM) Conference. IEEE, 2014. http://dx.doi.org/10.1109/gem.2014.7048122.
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Alves, Anderson Vinicius Silva, Wandson dos Santos de Almeida, Eliana Midori Sussuchi, Susana Oliveira de Souza, Francesco D'Errico i Jose Joatan Rodrigues Junior. "Low-diffusion PVA-GTA Fricke gel with silver nanoparticles". W Latin America Optics and Photonics Conference. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/laop.2022.w4a.40.
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The PVA-GTA Fricke Gel is a three-dimensional tissue-equivalent dosimeter that can be analyzed with optical imaging techniques. In this work we demonstrate that the addition of silver nanoparticles to the gel reduces the diffusion effect.
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Inoue, Shota, Hidemitsu Furukawa, Ajit Khosla, Masaru Kawakami i Kazuyuki Sakai. "Development of high-strength gel dosimeter made by 3D gel printer". W Nano-, Bio-, Info-Tech Sensors and 3D Systems, redaktor Vijay K. Varadan. SPIE, 2018. http://dx.doi.org/10.1117/12.2296499.
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VALENTE, M., G. BARTESAGHI, G. GAMBARINI, D. BRUSA, G. CASTELLANO i M. CARRARA. "FRICKE GEL DOSIMETER TISSUE-EQUIVALENCE: A MONTE CARLO STUDY". W Proceedings of the 10th Conference. WORLD SCIENTIFIC, 2008. http://dx.doi.org/10.1142/9789812819093_0104.
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