A Varian 4 MeV isocentric therapy accelerator has been modified to perform also as a CT scanner. The goal is to provide low cost computed tomography capability for use in radiotherapy. The system will have three principal uses. These are (i) to provide 2- and 3-dimensional maps of electron density distribution for CT assisted therapy planning, (ii) to aid in patient set up by providing sectional views of the treatment volume and high contrast scout-mode verification images and (iii) to provide a means for periodically checking the patients anatomical conformation against what was used to generate the original therapy plan. The treatment machine was modified by mounting an array of detectors on a frame bolted to the counter weight end of the gantry in such a manner as to define a 'third generation' CT Scanner geometry. The data gathering is controlled by a Z-80 based microcomputer system which transfers the x-ray transmission data to a general purpose PDP 11/34 for processing. There a series of calibration processes and a logarithmic conversion are performed to get projection data. After reordering the projection data to an equivalent parallel beam sinogram format a convolution algorithm is employed to construct the image from the equivalent parallel projection data. Results of phantom studies have shown a spatial resolution of 2.6 mm and an electron density discrimination of less than 1% which are sufficiently good for accurate therapy planning. Results also show that the system is linear to within the precision of our measurement (≈ .75%) over a wide range of electron densities corresponding to those found in body tissues. Animal and human images are also presented to demonstrate that the system's imaging capability is sufficient to allow the necessary visualization of anatomy.

Thesis (M.Sc.). / Written for the Dept. of Medical Radiation Physics. Title from title page of PDF (viewed 2008/05/13). Includes bibliographical references.

In external electron beam therapy arbitrarily shaped inserts (cutouts) are used to define the contours of the irradiated field. This thesis describes the implementation and verification of a software system to calculate output factors for cutouts using Monte Carlo simulations. The design goals were: (1) A stand-alone software system running on a single workstation. (2) Task oriented graphical user interface with shape input capability. (3) Implementation on Mac OS XRTM (10A.x Tiger). (4) CPU multicore support by job splitting. (5) EGSnrc (Patch level V4-r2-2-5) for particle transport and dose scoring. (6) Validation for clinical use. / The system, called Cutout Manager, can calculate output factors with 1% statistical error in 20 minutes on Mac Pro computer (Intel XeonRTM, 4 cores). When the BEAMnrc linac model correctly reproduces percentage depth doses in the buildup region and around R100, calculated and measured output factors are in good agreement with precision measurements of circular cutouts at 100 cm source-to-surface distance (SSD) and extended SSD. Cutout Manager simulations are consistent with measurements of clinical cutouts within a 2% error margin.

Thesis (M.S.)--University of Texas at El Paso, 2008. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (M.Sc.). / Written for the Medical Physics Unit. Title from title page of PDF (viewed 2009/06/23). Includes bibliographical references.

Thesis (M.Sc.)--University of Alberta, 2010. / A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Medical Physics, Department of Physics. Title from pdf file main screen (viewed on July 17, 2010). Includes bibliographical references.

No description available.

Structure-property relationships were investigated for electron beam(EB) irradiated monomeric and polymeric systems. The objectives were to study the feasibility of preparing systems of potential application, and to characterize these systems in terms of structure-property behavior. In this thesis, the basic theories on radiation chemistry were first reviewed. Next, five different studies on the application of EB radiation were discussed. In the first study on the surface modification of the methacrylic acid derivative of the glycidyl ether of bis-phenol A(bis-GMA) substrates, considerable changes in wetting characteristics were observed using functionalized poly(dimethyl siloxane)(PDMS) oligomers as surface modifiers. Systematic studies were conducted to investigate the effects of the type of functionality, the molecular weight of PDMS and the radiation dosage, etc. The second subject was on the structure-property behavior of EB crosslinked caprolactone-allyl glycidyl ether(CL-AGE) copolymers. EB radiation was utilized to crosslink these materials at various temperatures both above and below the crystalline melting point. The final solid state properties were found to be strongly dependent on the morphological state of the CL-AGE copolymer at the time of EB irradiation. In the third study, models of time-temperature-energy(TTE) diagrams in an idealized EB radiation curing system were developed to help provide a conceptual understanding of the TTE relationship. Three general adiabatic cases were presented with increasing degree of complexity: the first considered only heating through EB energy dissipation, while the second and third attempted to include a kinetic exotherm, and the effects of glass transition and vitrification behavior, respectively. The fourth study focused on the effects of EB irradiation on the mechanical and thermal properties of poly(phenylene sulfide). The effects of morphological state and atmospheric environment such as air or nitrogen during the irradiation process were investigated in terms of structure—property behavior. In the fifth study, two systems(symmetric and asymmetric) based on the controlled distribution of bis-GMA within a crosslinked nitrile rubber(NBR) network were prepared utilizing EB irradiation. The prepared symmetric and asyrnronetric distributions of bis-GMA and the morphological structure of the NBR/bis-GMA system were investigated by dynamic mechanical as well as by FTIR and polarizing optical microscopy analyses. / Ph. D.

The purpose of this thesis is to validate the Monte Carlo algorithm for electron radiotherapy in the Eclipse™ treatment planning system (TPS), and to compare the accuracy of the Electron Monte Carlo algorithm (eMC) to the Pencil Beam algorithm (PB) in Eclipse™. Dose distributions from GafChromic™ EBT3 film measurements were compared to dose distributions from eMC and PB treatment plans. Measurements were obtained with 6MeV, 9MeV, and 12MeV electron beams at various depths. A 1 cm thick solid water template with holes for bone-like and lung-like plugs was used to create assorted configurations and heterogeneities. Dose distributions from eMC plans agreed better with the film measurements based on gamma analysis. Gamma values for eMC were between 83%-99%, whereas gamma values for PB treatment plans were as low as 38.66%. Our results show that using the eMC algorithm will improve dose accuracy in regions with heterogeneities and should be considered over PB. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

Diss. (sammanfattning) Umeå : Umeå universitet, 2008. / Härtill 4 uppsatser.