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

Thesis (Ph.D.) - Carleton University, 2005. / Includes bibliographical references (p. 148-161). Also available in electronic format on the Internet.

Thesis (Ph. D. in Physics)--Vanderbilt University, May 2009. / Title from title screen. Includes bibliographical references.

Thesis (M. Sc.)--University of Canterbury, 2006. / Typescript (photocopy). "Year: 2004-2006." Includes bibliographical references (leaves 108-112). Also available via the World Wide Web.

Thesis (MTech (Radiography))--Peninsula Technikon, 2004 / The radiation risks associated with children are higher than the risk for adults. Children have growing organs and they have a longer life expectancy than that of adults. As a consequence the effects of damage from radiation could be greater than in adults. Children who receive radiation damage may pass genetic damage onto future generations. This study was carried out to investigate the optimal effective x-ray dose young children need to receive who have radiographic examination to the chest at Tygerberg Hospital, South Africa. Chest radiographs are documented as being the most common radiographic examination done on children. The age groups of children participating in this study were 0-1 year, 1-5 years and 5-10 years. A total of 67 children were involved and the absorbed doses for 134 views of the anterior-posteria (AP) chest and lateral chest were measured. Entrance surface dose (ESD) values were determined, and measured mean ESD (mGy) and the ESD range was reported for each age group. This was done by attaching thermolurninescent dosirneters (TLD pellets) to the patients skin at the entrance point of the x-ray beam. The results were compared to similar studies done in Ireland and Nigeria From the ESD values obtained the absorbed doses ofthe eyes, heart, liver, thyroid and genitals could be calculated by using the "Childdose" programme ofthe NRPB. The ESD dose levels for South Africa compare favourably with Ireland. However the Nigerian values differed greatly from those of Ireland and South Africa It was very encouraging to note the comparative results achieved at Tygerberg Hospital especially due to the fact that this was the first time such study had been conducted in the Tygerberg Hospital Radiology Department. The results also compare favourable with that achieved by a group working in the United Kingdom. This group does similar surveys every five years as part of their radiation protection programme. The results were also in line with the UNSCEAR document of2000. v This study could serve as a valuable source of reference to radiographers and radiologists when performing paediatric radiology especially as the radiation absorbed dose could be used as a baseline to create awareness of size of dose received, and to limit deleterious radiation doses to patients and to prevent unnecessary exposures. A second significant outcome of the study was the effect that added filters had on the x-ray beam generated. Experiments were done in which the filtration filters were added sequentially. It was found that if the filtration was increased to 2mmAl the dose to the patient decreased by more than 20%. At 50 and 60 kV the density of the x-ray image on film only increased by 2%. From these results it may be concluded that an increase in filtration thickness used for paediatric chest x-rays should be giVIng reduced dose readings and assisting with radiation protection ofthe patient.

Purpose: The use of 106Ru eye plaques for the treatment of intraocular malignancies has produced inconsistent clinical outcomes and has even resulted in treatment failures. I hypothesized that inconsistent clinical results were attributable to high uncertainties in 106Ru eye plaque dosimetry. Furthermore, I hypothesized that more accurate methods for assessing radiation dose from eye plaques would lead to more reliable treatment planning and therefore better overall clinical outcomes. Methods: A Solid Water “eye” phantom with several novel features was developed for radiochromic film eye plaque dosimetry. Films perpendicular to the central axis of the eye plaques were sandwiched between inserts in the phantom. Small holes in the inserts enabled the film to be marked with respect to the eye plaques, assuring exact geometrical co-registration. In cooperation with the manufacturer, special thin radiochromic films were developed and utilized to permit dosimetric measurements almost at the eye plaque surface. Precise film punches were developed for the purpose of cutting films with diameters as small as 8.5 mm and making cutouts in films without damaging the cut edges. Findings from a secondary dosimetry system, utilizing a small silicon diode in a water tank, were compared to film data. In addition to testing the new dosimetry methods with 106Ru eye plaques, which utilize high energy (MeV) β emissions, this approach was also applied to 125I containing eye plaques, which due to their inherently lower energy (keV) γ emission spectrum, raised additional dosimetric complications. In the latter case dosimetry, films and the diode were calibrated for absolute dosimetry using calibrated 125I seeds in Solid Water and water, respectively, applying the TG-43 formalism. A novel calibration method of radiochromic film for low-energy photon dosimetry was introduced. Monte Carlo simulations were used to convert the results measured in Solid Water to liquid water, and to compare measured and simulated dosimetric results. Results: Dosimetric characterization of both 106Ru eye plaques and a novel concept 125I eye plaque are described. Furthermore, dosimetry of a 20 mm 125I Collaborative Ocular Melanoma Study (COMS) eye plaque validated the presumed substantial dose reduction resulting from its gold alloy backing and seed carrier insert predicted by Monte Carlo simulations. Dose distributions measured with radiochromic film were in good agreement with diode measurements and Monte Carlo simulations. Replicate film results were reproducible from 0.9% to 5.5%. As little as 4% non-uniformities in planar dose rates were easily detected using 106Ru eye plaques. The novel 125I eye plaques had uniform dose distributions. Dosimetric characterization of the 20 mm COMS plaque demonstrated that the plaque’s dose rate was 15% lower than that predicted by homogenous TG-43 calculations. Lastly, Monte Carlo simulations indicated dose conversion factors between water and film in Solid Water compared to water and Solid Water alone differed by as much as 16.8%. Change in the calcium content of Solid Water from 2.3% to 1.7% resulted in a 3.3% calculated difference in dose to film and in an 8.7% difference in dose to Solid Water. Conclusions: Precise and reproducible 106Ru and 125I eye plaque dosimetry was achieved utilizing radiochromic film in a water equivalent phantom and a small semiconductor diode in water. Co-registration of eye plaques and films permitted not only precise treatment planning calculations along the central axis of the plaque, but also made it possible to account for dosimetric non-uniformities using 2D or 3D methodologies. A calibrated 125I seed enabled calibration of the film and the diode for absolute dosimetry of 125I containing eye plaques. Dose measurements on the inner surface of the plaques provided precise assessment of the scleral dose, its homogeneity, and of the active area of the plaques for coverage determination. Monte Carlo simulations facilitated conversion of doses measured in various media to liquid water.

In this work, we have developed a robust daily quality assurance (QA) system for pencil-beam scanning (PBS) dosimetry. A novel phantom and multi-PTV PBS plan were used in conjunction with the Sun Nuclear Daily QA3 multichamber detector array to verify output, range, and spot position. The sensitivity to detect change in these parameters with our designed tests was determined empirically. Associated tolerance levels were established based on these sensitivities and guidelines published in recent American Association of Physics in Medicine (AAPM) task group reports. The output has remained within the 3% tolerance and the range was within ±1mm. Spot position has remained within ±2mm. This daily QA procedure is quick and efficient with the time required for setup and delivery at less than 10 minutes. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

No description available.

Magnesium tetraborate is a candidate phosphor for a laser-heated thermoluminescence (TL) dosimetry system which is under development. Near tissue-equivalent radiation absorption properties and reported sensitivity to low radiation doses offer advantages over commonly employed LiF phosphors. Sintered wafers suitable for routine measurement were prepared. The effects of powder preparation conditions and activator concentration on TL sensitivity were investigated. Samples with additional impurities (co-doped samples) were prepared in order to increase sensitivity through coactivation or sensitization effects. TL emission spectra were employed to evaluate the effects of co-doping. / Master of Science / incomplete_metadata

Thesis (M.Sc.) (Hons)-- University of Western Sydney, 2002. / "A thesis submitted in fulfillment of the requirements for the Degree of Master of Science (Honours) in Physics at the University of Western Sydney" "September 2002" "Kin Wa (Karl) Chan of Medical Physics Department of Westmead Hospital and the University of Western Sydney"-- t.p. Bibliography: leaves 100-105.