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in vivo patient dose verification of volumetric modulated arc therapy including stereotactic body radiation treatment applications using portal dose imagesMcCowan, Peter Michael 12 1900 (has links)
The complexity of radiation therapy delivery has increased over the years due to advancements in computing and technical innovation. A system of dose delivery verification has the potential to catch treatment errors and therefore improve patient safety. The goal of this thesis was to create a portal image-based in vivo dose reconstruction model for volumetric modulated arc therapy (VMAT) deliveries, specifically for stereotactic body radiation therapy (SBRT). This model-based approach should be robust and feasible within a clinical setting. VMAT involves the modulation of dose rate, gantry speed, and aperture shaping while the treatment gantry (i.e., x-ray beam) rotates about the patient. In this work, portal images were acquired using an amorphous silicon electronic portal imaging device (a-Si EPID).
A geometrical characterization of the linear accelerator (linac) during VMAT delivery was performed. An angle adjustment method was determined which improves each EPID’s angular accuracy to within ±1° of the true physical angle.
SBRT delivers large doses over fewer fractions than conventional radiotherapy, therefore, any error during an SBRT delivery will have a greater impact on the patient. In this work, a robust, model-based SBRT-VMAT dose reconstruction verification system using EPID images was developed. The model was determined to be clinically feasible.
The accuracy of a 3D in vivo dose reconstruction, using all the EPID images acquired during treatment, is sensitive to the chosen frame averaging per EPID image: the greater the frame averaging, the larger the reconstruction error. Optimization of the EPID frame averaging number as a function of average linac gantry speed and dose per fraction were determined.
The EPID-based in vivo dose reconstruction model for SBRT-VMAT developed here was determined to be robust, accurate, and clinically feasible as long as adjustments were made in order to correct for EPID image geometrical errors and frame-averaging errors. / May 2016
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Optimisation of radiotherapy treatment planning for tumours of the breast, prostate and brainNeal, Anthony James January 1995 (has links)
No description available.
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Optimisation of digital image intensifier and computed radiography systemsMarshall, Nicholas W. January 1998 (has links)
No description available.
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Review and development of an uranium internal dosimetry and monitoring programme at an uranium plantBeeslaar, Frederik Johannes Louw 03 May 2013 (has links)
A research report submitted to the Faculty of Science, University of the
Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the
degree of Masters of Science
Johannesburg 2013 / Monitoring for internal exposures to uranium and calculating the corresponding
Committed Effective Dose (CED) can be complex. Several contributing
parameters such as the differences in the physiochemical nature of the uranium
compound, the nature of the exposure scenario, variances in human metabolic
behaviour and the capabilities of available bioassay techniques add uncertainty in
developing an Internal Dosimetry and Monitoring Programme (IDMP). Necsa’s
IDMP was reviewed and found to be in line with best international practices and
adequate for monitoring routine exposures to Type M uranium. As found in
literature and shown in the present study, the monitoring for Type S uranium is
problematic. The present study recommends continuance with the current Type S
monitoring programme, however, the need for faecal analysis was identified. A
combination of bioassay techniques can assist in determining the unknowns in the
abovementioned contributing parameters. Analysis done to quantify the effect of
differences in the contributing parameters has brought an understanding on how
these parameters can influence and IDMP and knowledge gained from the present
study will further enhance the programme and assist in developing the necessary
documentation, providing the technical justification for Necsa’s uranium IDMP.
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A software system for radionuclide dosimetry with applications.McKay, Erin, Physics, Faculty of Science, UNSW January 2007 (has links)
Radiation dosimetry is necessary for optimising radiation-based medical procedures for individual patients but in the field of nuclear medicine there are few widely available or widely used tools for performing this kind of analysis. Those tools that are available tend to focus on one particular component of the dosimetry problem and integrating tools to form a complete system is left to the end-user. A software system for performing individual, image-based dosimetry analysis of nuclear medicine studies has been developed and validated. The system consists of a suite of tools that use common file formats and data models. The tools can be integrated to form applications by means of a simple scripting system. One tool is a gamma camera simulator that can produce realistic images of dynamic activity distributions in planar or tomographic formats. Simulated imaging studies produced by this tool are used to validate the other tools in the system. In addition, the system implements a method of simulation assisted quantitation which is shown to achieve high accuracy in both software and physical phantom studies. The system is applied to the dosimetry of I-131 Lipiodol, a therapeutic agent used to treat primary and secondary cancers of the liver. Simulation studies are used to validate the analytic methods used. Studies of a series of patients, treated over a period 10 years, are retrospectively analysed using a selection of methods appropriate to the available data. The results of the analysis demonstrated a large range of lung doses from 1 to 10 Gy/GBq administered. The median absorbed dose in liver was 3 Gy (range 1 - 10 Gy) and the median absorbed dose in tumor was 19 Gy (range 5 - 84 Gy). The large individual variation reinforces the necessity of individualised dosimetry for treatment planning and follow up.
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A software system for radionuclide dosimetry with applications.McKay, Erin, Physics, Faculty of Science, UNSW January 2007 (has links)
Radiation dosimetry is necessary for optimising radiation-based medical procedures for individual patients but in the field of nuclear medicine there are few widely available or widely used tools for performing this kind of analysis. Those tools that are available tend to focus on one particular component of the dosimetry problem and integrating tools to form a complete system is left to the end-user. A software system for performing individual, image-based dosimetry analysis of nuclear medicine studies has been developed and validated. The system consists of a suite of tools that use common file formats and data models. The tools can be integrated to form applications by means of a simple scripting system. One tool is a gamma camera simulator that can produce realistic images of dynamic activity distributions in planar or tomographic formats. Simulated imaging studies produced by this tool are used to validate the other tools in the system. In addition, the system implements a method of simulation assisted quantitation which is shown to achieve high accuracy in both software and physical phantom studies. The system is applied to the dosimetry of I-131 Lipiodol, a therapeutic agent used to treat primary and secondary cancers of the liver. Simulation studies are used to validate the analytic methods used. Studies of a series of patients, treated over a period 10 years, are retrospectively analysed using a selection of methods appropriate to the available data. The results of the analysis demonstrated a large range of lung doses from 1 to 10 Gy/GBq administered. The median absorbed dose in liver was 3 Gy (range 1 - 10 Gy) and the median absorbed dose in tumor was 19 Gy (range 5 - 84 Gy). The large individual variation reinforces the necessity of individualised dosimetry for treatment planning and follow up.
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A software system for radionuclide dosimetry with applications.McKay, Erin, Physics, Faculty of Science, UNSW January 2007 (has links)
Radiation dosimetry is necessary for optimising radiation-based medical procedures for individual patients but in the field of nuclear medicine there are few widely available or widely used tools for performing this kind of analysis. Those tools that are available tend to focus on one particular component of the dosimetry problem and integrating tools to form a complete system is left to the end-user. A software system for performing individual, image-based dosimetry analysis of nuclear medicine studies has been developed and validated. The system consists of a suite of tools that use common file formats and data models. The tools can be integrated to form applications by means of a simple scripting system. One tool is a gamma camera simulator that can produce realistic images of dynamic activity distributions in planar or tomographic formats. Simulated imaging studies produced by this tool are used to validate the other tools in the system. In addition, the system implements a method of simulation assisted quantitation which is shown to achieve high accuracy in both software and physical phantom studies. The system is applied to the dosimetry of I-131 Lipiodol, a therapeutic agent used to treat primary and secondary cancers of the liver. Simulation studies are used to validate the analytic methods used. Studies of a series of patients, treated over a period 10 years, are retrospectively analysed using a selection of methods appropriate to the available data. The results of the analysis demonstrated a large range of lung doses from 1 to 10 Gy/GBq administered. The median absorbed dose in liver was 3 Gy (range 1 - 10 Gy) and the median absorbed dose in tumor was 19 Gy (range 5 - 84 Gy). The large individual variation reinforces the necessity of individualised dosimetry for treatment planning and follow up.
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Experimental validation and evaluation of uncertainty in the monte carlo modeling of electron irradiation of complex objectsTutt, Teresa Elizabeth 15 May 2009 (has links)
Monte Carlo method is an invaluable tool in the field of radiation protection, used to
calculate shielding effectiveness, as well as dose for medical applications. With few
exceptions, most of the objects currently simulated have been homogeneous materials
that vary in density by a factor of 3 or less. In the irradiation of very heterogeneous
objects, particularly layered or leafy food items, one will encounter air pockets within
the bundle as a matter of course. These pockets will cause variations in density of up
to three orders of magnitude. Air pockets in a tissue equivalent phantom were found
to produce “hot spots” in the dose distribution, and introduced significant deviations
between the calculated and measured distribution of dose to the phantom. To date,
very little published work had been done in the area of Monte-Carlo simulation of
objects of such disparate density. Before Monte Carlo methods can be used
successfully in this regime, further code development and experimental validation
will be necessary, of which this work is just a beginning. Phantoms were made of
corrugated low-Z material similar in electron density to plant based material. These
phantoms incorporated air gaps of comparable size to those found in the leafy objects
of interest. Dimensions were chosen to bracket electron ranges in the material of the objects modeled. Monte Carlo analysis will provide a reasonable qualitative picture of
the dose distribution, but such a picture is not yet sufficiently accurate in a
quantitative sense. Air gaps within the plant material produced large discrepancies
between calculation and measurement. Smaller air gaps were observed to produce
greater discrepancy between calculation and measurement.
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Design, construction, and analysis of a skin contamination dosimeter /Cazalas, Edward J. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 114-118). Also available on the World Wide Web.
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Radiochromic dye dosimetry of neutron and gamma fieldsWankerl, Max Wilhelm, 1939- January 1969 (has links)
No description available.
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