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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

The dosimetric accuracy of megavoltage photon and electron beams in radiotherapy

Nisbet, Andrew January 1994 (has links)
In this thesis, a detailed review and analysis is undertaken of the numerical and theoretical data employed in the various National and International Dosimetry Protocols and Codes of Practice currently in use. Air kerma to dose conversion factors for megavoltage photon and electron beams are then derived, using each of the protocols, for a variety of commonly used ionisation chambers and it is found that differences in the resultant values are present for both photon and electron beams. For example, for a NE2571 graphite walled cylindrical ionisation chamber, the maximum variation in the air kerma to dose conversion factor for photons <I>C<sub>w,λ</sub></I> occurs at a "nominal" energy of 25MV, where the difference between the maximum and minimum values of <I>C<sub>w,λ </sub></I>is 5.1%, while the maximum difference between the different protocols in the air kerma to dose conversion factor for electrons <I>C<sub>w,e </sub></I>occurs at a mean incident energy of 9 MeV, where the difference between the maximum and minimum values of <I>C<sub>w,e</sub></I> is 2.7%. Analysis of the conversion factors indicates that the cause of these differences is due to a combination of both the numerical data and theoretical factors employed, although the major contributions to the differences arise from the use of different sets of stopping power ratios in the different protocols; in turn the use of different sets of stopping power ratios arises partly from different methods of specifying beam quality. An experimental approach was, therefore, developed to determine the consistency of each protocol's air kerma to dose conversion factors with an absolute value for one quality of beam, i.e. the relationship to a photon calibration standard, and also to examine the consistency between photon and electron beam modalities. When Cobalt-60 gamma rays were used as a calibration quality and comparative measurements were made in photon beams of nominal energies from 6MV to 25MV, and electron beams of nominal incident energies from 5MeV to 20MeV, inconsistencies were found in the majority of protocols and, for photon beams this was found to be attributable to inadequate description of photon beam quality.
82

Optimization of Dose Schedules in Radiotherapy

Miasnikof, Pierre 18 March 2013 (has links)
Purpose: Fractionation in radiotherapy is the scheduled break up of a total treatment dose into individual doses. The goal of this thesis is to seek a mathematically optimal dose schedule, in the context of a biological tissue dose-response model, the linear-quadratic function. Methods: We examined the mathematical properties of the fractionation problem in the context of an arbitrary number of sensitive-structure constraints and determined the properties of the optima. We also implemented a numerical search technique to solve the problem. Results: On the theoretical side, we confirmed and extended the results in the literature. We showed the optima always occur at the intersection of two or more constraints or at the equal dose per fraction point (or at any arbitrary feasible point on the boundary, which includes the two points just mentioned). On the numerical side, we successfully implemented a simulated annealing algorithm to our problem.
83

A radiobiological basis for bioeffect planning /

Wigg, David, Unknown Date (has links)
The main purpose of this thesis is to encourage the development of bioeffect planning as an experimental tool by which means bioeffect plans may be compared with standard isodose plans. This thesis also addresses the fundamental problems of the derivation of useful biological models for clinical application and the description of tumour and normal tissue parameter values and their variability. Particular emphasis has been placed on comparing the predictive value of the models and parameters against clinical results of fractionated and continuous irradiation either alone or combined. / Thesis (PhD)--University of South Australia, [1999]
84

Investigation into the dosimetric effects of abutting multi-leaf-collimated photon fields with extended source-to-surface electron fields : [a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Medical Physics in the University of Canterbury, New Zealand] /

Steel, Jared. January 2007 (has links)
Thesis (M. Sc.)--University of Canterbury, 2007. / Typescript (photocopy). "Year: 2005-2007." Includes bibliographical references (leaves 130-132). Also available via the World Wide Web.
85

ARCON in experimental and clinical radiotherapy /

Rojas Callejas, Ana Maria, January 2004 (has links)
Diss. (sammanfattning) Umeå : Univ., 2004. / Härtill 5 uppsatser.
86

Short-term pulmonary side-effects following radiation therapy in breast cancer /

Lind, Pehr, January 1900 (has links)
Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.
87

Clinical application of intensity and energy modulated radiotherapy with photon and electron beams /

Mu, Xiangkui, January 2005 (has links)
Diss. (sammanfattning) Umeå : Univ., 2005. / Härtill 4 uppsatser.
88

Investigations into static multileaf collimator based intensity modulated radiotherapy /

Williams, Matthew John. January 2004 (has links)
Thesis (Ph. D.)--University of New South Wales, 2004. / Also available online.
89

Radiolabeled HER-2 binding affibody molecules for tumor targeting : preclinical studies /

Steffen, Ann-Charlott, January 2006 (has links)
Diss. (sammanfattning) Uppsala : Uppsala universitet, 2006. / Härtill 6 uppsatser.
90

Professional communication practices of radiotherapists in the workplace and classroom in higher education in the Western Cape, South Africa /

Wyrley-Birch, Bridget Diana. January 2008 (has links)
Thesis (MTech (Radiography))--Cape Peninsula University of Technology, 2008. / Includes bibliographical references (leaves 186-202). Also available online.

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