published_or_final_version / Medicine / Master / Doctor of Medicine

published_or_final_version / Obstetrics and Gynaecology / Doctoral / Doctor of Philosophy

No description available.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science, 2017 / Aim: The aim of this study was to quantify random and systematic setup errors in a population of head and neck cancer patients for the purposes of evaluating departmental positioning and immobilization techniques, verification and treatment protocols, as well as validating the treatment margins used. Methods and Materials: All patients had more than one phase of radiation, each consisting of different megavoltage photon field arrangements. Some phases were also treated with electron fields in addition to the photon fields. Random and systematic setup errors in all three principal directions were calculated for two groups of patients, using record and verify system couch position data. For one group (20 patients) the positioning and immobilization device system was mechanically localized to the treatment couch, and for the other group (38 patients), it was visually centered on the treatment couch. Within both groups of patients, the patient position was either verified online with portal imaging or verified offline on a conventional radiotherapy simulator. Results: For the patient group treated with the base plate visually centered on the treatment table the population random and systematic setup errors calculated for the photon fields were only indicative of setup uncertainties in the anterior-posterior direction. For the patient group treated with the base plate localized to the treatment couch, the population random and systematic setup errors were found to be within the 5 mm clinical to planning target volume expansion margin used at Livingstone Hospital. Due to treatment couch position differences from fraction to fraction, setup errors made during this study could not reliably be determined for electron field treatments Conclusions: Results indicate that the base plate should be localized to the treatment couch when calculating random and systematic setup errors for photon fields using the couch position as a surrogate for patient position. For this method to be used to calculate setup errors for electron fields, shielding should always be fastened to the same position at the endface of the applicator. Offline and online verification did not significantly influence systematic setup errors. / XL2018

I have been intensively involved in the research on the application of currently available knowledge for the improvement of cancer care. This research covers the types of treatment that are appropriate for different clinical conditions (benchmarking and guidelines), planning services to improve access for patients, monitoring service delivery through patterns of care studies and development of the knowledge and skills of the cancer workforce. I devoted considerable effort to better educating the cancer workforce by measuring cancer teaching and developing model curricula and innovative teaching programs. I have made substantial contributions to knowledge about best practice by developing clinical practice guidelines and have developed tools and plans for cancer service delivery and have had a major influence on the training of the undergraduate and specialist medical workforce about cancer.

Doctor of Health Science / It is well documented that for prostate cancer patients undergoing radiation therapy there is a correlation between target volume displacement and changes in bladder and rectal volumes. However, these studies have used a methodology that has captured only a subset of all treatment positions. This research used daily Computer Tomography (CT) imaging to comprehensively assess organ volumes, organ motion and their effect on dose, something that has never been performed previously, thus adding considerably to the understanding of the topic. Daily CT images were obtained using a Siemens Primus Linear Accelerator equipped with an in-room Somatom CT unit in the accelerator suite, marketed as ‘Primatom’, to accurately position the patient prior to treatment delivery. The internal structures of interest were contoured on the planning workstation by the investigator. The daily volume and location of the organs were derived from the computer to assess and analyse internal organ motion. The planned dose distribution was then imported onto the treatment CT datasets and used to compare the planned dose to i) the actual isocentre, where the isocentre was actually placed for that fraction, ii) the uncorrected isocentre, by un-doing any on-line corrections performed by the treatment staff prior to treatment delivery, and iii) the future isocentre, by placing the isocentre relative to internal organ motion on a daily basis. The results of this study did not confirm a statistically significant decrease in rectum volumes over time (hypothesis 1), however large fluctuations in bladder volume were confirmed (hypothesis 2). Internal organ motion for the rectum and bladder was demonstrated to be related to organ filling. Ideal planning volumes for these organs have been reported to minimise systematic and random uncertainty in the treatment volumes. An observed decrease in prostate volume over time, a systematic uncertainty in the location of the prostate at the time of the planning CT scan and a significant relationship between prostate centre of volume and rectum and bladder volumes has resulted in a recommendation that patients should be re-scanned during treatment to ensure appropriate clinical target volume coverage. A significant relationship between rectal and bladder volumes and the dose delivered to these organs was found (hypothesis 3). The dose delivered to the planning target volume was not related to the rectal or bladder volumes, although it was related to the motion of these organs. Despite these results only minimal effects on the dose delivered to any of the three isocentres occurred, indicating that the planned dose was accurately delivered using the methodology presented here (hypothesis 4). However the results do indicate that the patient preparation instructions need to be improved if margins are to be reduced in the future. It is unrealistic to assume that Image Guided Radiation Therapy will ever become routine practice due to infrastructure costs and time limitations. This research will inform radiation therapy centres of the variables associated with prostate cancer treatment on a daily basis, something that has never before been realistically achievable. As a result centres will be able to devise protocols to improve treatment outcomes.

Bibliography: leaves 159-194 / xi, 194 leaves, [3] leaves of plates : ill. (2 col.) ; 31 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1986

The cell survival curve is the only means by which to both qualitatively and quantitatively assess morphologic alterations directly resulting from in vitro irradiation of the cell. A ������Co cell survival curve experiment has successfully demonstrated the response of the AtT-20 clone mammalian cell line to the effects of gamma rays. With the results of this experiment, a low LET radiation cell survival curve now exists to be used as a comparative upon the completion of BNCT cell survival curves. / Graduation date: 1995

published_or_final_version / Nursing Studies / Master / Master of Nursing in Advanced Practice

No description available.