Thesis (Ph. D.)--University of Wisconsin--Madison, 2000. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 205-212).

Advanced-stage nasopharyngeal carcinoma (NPC) presents very difficult scenarios for radiation therapy (RT) planning. The infiltration of tumor to the skull base and beyond means that the tumor is very close to critical normal organs (organs at risk, OARs). Despite the advent of intensity-modulated radiotherapy (IMRT) treatment technique---the state-of-art RT technique, conflicting requirements between organ protection and target dose conformity is still problematic. The objectives of the present research are (1) to investigate the dosimetry properties of IMRT treatment in advanced-stage NPC in respect of its dosimetric limitations and planning problems, (2) to develop new methods and tools to resolve such problems, in particular to improve the quality of treatment plans and efficiency of the dose planning and optimization process. A series of four inter-linked studies were conducted to address these issues. / In conclusion, the solutions to several major problems in IMRT planning for advanced-stage NPC were investigated and established. It has been demonstrated in this research that, by applying these methods and tools, significant improvement in the dosimetry and efficiency of IMRT treatment planning can be accomplished as compared with conventional IMRT planning techniques. It is expected that such would translate into an improvement in treatment throughput, better tumor control and reduction in normal tissues complications. The methods developed have potential to be applied to all stages of NPC and to other tumor sites. / The first study was to improve the efficacy in target coverage and organs sparing using an "organ-splitting" approach. The OARs which overlapped with targets were split into target-overlapping and non-overlapping segments and each segment was assigned with different constraints parameters to increase the degree of flexibility during optimization. As a result, a steep gradient in the dose distribution at the regions of interface between the targets and normal critical organs could be achieved and treatment quality was improved. In the second study, a thorough dosimetric comparison between conventional 2-dimensional (2D) RT and IMRT plans was conducted to determine, with reference to outcome of 2D treatments, the extended tolerance dose limits for the critical organs, especially that of the brainstem and spinal cord, and their planning organ at risk volume. Such data could then serve as reference in IMRT planning when the dose of critical organs need be exceeded in order to allow adequate dose to a very close by target. In the third study, the feasibility of using interpolated contours for segmentation of targets and OARs in IMRT planning was investigated. The result indicated that the use of interpolated contours in IMRT planning could significantly reduce the contouring time by about 50% without degrading the target coverage and OARS sparing. In the final study, an array of dose constraint templates that could accommodate different degrees of overlap between the targets and OARs, together with a template selection program, were developed to improve the efficiency of IMRT planning. By applying the methods and tools developed, IMRT treatment planning of advanced NPC could become more efficient and less dependent on planner's experience. / Chau, Ming Chun. / Adviser: Anthony Chan Tak Cheung. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 0948. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 118-128). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / School code: 1307.

Diss. (sammanfattning) Umeå : Umeå universitet, 2006. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Univ., 2004. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2006. / Härtill 4 uppsatser.

Thesis (M.S.)--University of Toledo, 2009. / "In partial fulfillment of The Degree of Master of Science in Biomedical Sciences." Title from title page of PDF document. Bibliography: p. 94-102.

Thesis (M.S.)--University of Toledo, 2009. / "In partial fulfillment of the requirements for the degree of Master of Science in Biomedical Sciences." Title from title page of PDF document. Bibliography: p. 34-35.

It is estimated that more than 60% of cancer patients will receive radiotherapy (RT). Medical images acquired from different imaging modalities are used to guide the entire RT process from the initial treatment plan to fractionated radiation delivery. Accurate identification of the gross tumor volume (GTV) on computed tomography (CT), acquired at different time points, is crucial for the success of RT. In addition, complementary information from magnetic resonance imaging (MRI), positron emission tomography (PET), cone-beam computed tomography (CBCT) and electronic portal imaging device (EPID) is often used to obtain better definition of the target, track disease progression and update the radiotherapy plan. However, identifying tumor volumes on medical image data requires significant clinical experience and is extremely time consuming. Computer-based methods have the potential to assist with this task and improve radiotherapy. In this thesis a method was developed for automatically identifying the tumor volume on medical images. The method consists of three main parts: (1) a novel rigid image registration method based on scale invariant feature transform (SIFT) and mutual information (MI); (2) a non-rigid registration (deformable registration) method based on the cubic B-spline and a novel similarity function; (3) a gradient-based level set method that used the registered information as prior knowledge for further segmentation to detect changes in the patient from disease progression or regression and to account for the time difference between image acquisition. Validation was carried out by a clinician and by using objective methods that measure the similarity between the anatomy defined by a clinician and by the method proposed. With this automatic approach it was possible to identify the tumor volume on different images acquired at different time points in the radiotherapy workflow. Specifically, for lung cancer a mean error of 3.9% was found; clinically acceptable results were found for 12 of the 14 prostate cancer cases; and a similarity of 84.44% was achieved for the nasal cancer data. This framework has the potential ability to track the shape variation of tumor volumes over time, and in response to radiotherapy, and could therefore, with more validation, be used for adaptive radiotherapy.

Thesis (MTech (Biomedical Technology))--Cape Peninsula University of Technology, 2005 / The principal objective in irradiating tumours is to permanently inhibit their reproductive ability. More than half of all malignancies are primarily treated with radiation but tumours of different histologies differ greatly in response to radiotherapy as well as individual patients displaying great variability in response to treatment. The need for reliable assays predicting tumour and normal tissue response to radiation is therefore a prime objective of clinical oncology. The requirement of such a test would be that it would relate to clinical outcome Le. the possibility of recurrence of disease or of tumour control as well as indicating whether the treatment should be administered more aggressively or not. These are important factors that, if known, could be used as part of the treatment planning in radiotherapy and selection of best therapy modality. The colony forming c1onogenic assay has been shown to be a reliable reflection of a cells ability to maintain reproductive integrity after radiation exposure. In this study it has successfully been used to demonstrate the surviving fraction of cells but has the limitation of cells needing to process the ability to form colonies. Cells from primary tumours do not readily form colonies and may display poor anchorage making this assessment of radiosensitivity in the clinic less desirable. These data are presented together with unpublished data obtained using the micronucleus assay. Micronuclei frequency (MNF) varies in different cell types with test doses and provides a means to rank the cell in terms of response to radiation. In normal cells a linear inverse correlation exits between MNF and cell survival. However, MNF does not rank malignant cells according to their intrinsic survival to radiation displaying a weak correlation between MNF and cell survival.

Thesis (MTech (Radiography))--Cape Peninsula University of Technology, 2010. / The focus of this study is the role of the Radiation Therapist (RTT) in the assessment of pain in cancer patients. The study was carried out at a Radiotherapy Department of a large Teaching Hospital in Ghana and addressed the following research questions; 1) What is the role of the RTT in the assessment of pain in cancer patients, 2) Why should the RTTs’ role be extended to include pain assessment, 3) What are the challenges for the RTT when taking on the role of pain assessment in radiation oncology and 4) How can pain assessment become a routine role for the RTT in a busy radiation oncology department? 5) How would this extended role of the RTT assist management of patient? This study was conducted because many cancer patients suffer pain and to many, it can be more debilitating than the primary disease itself. The RTTs who are involved in the daily management of cancer patients during their radiation treatment can find it stressful to witness their patients going through such pain particularly when they do not have a role in the management of pain. In Ghana, there are few radiation oncologists (ROs) and therefore an extended scope for RTTs, that includes pain assessment and a meaningful contribution to the management of their patients’ pain, would be advantageous to all. A mixed method research approach was adopted for gathering quantitative and qualitative data. This included data collection of; interview, observation and review of existing document. A pain questionnaire SF-MPQ-2 by Melzack (2009) was adapted as a tool for assessing pain in the study participants.