Dissertation (Ph.D.).--University of Texas Graduate School of Biomedical Sciences at San Antonio, 2007. / Vita. Includes bibliographical references.

Thesis (M.S.)--University of Toledo, 2008. / "In partial fulfillment of the requirements for the degree of Master of Science in Biomedical Sciences." Title from title page of PDF document. Bibliography: pages 52-55.

Thesis (M.S.)--University of Toledo, 2008. / "In partial fulfillment of the requirements for the degree of Master of Science in Biomedical Sciences." Title from title page of PDF document. "Date of Defense: December 12, 2007" -- Approval page. Bibliography: p. 71-73.

The main subject matter of this thesis concerns radiotherapy patient scheduling subproblems formulated as four separate shop scheduling problem models (i.e. hybrid flowshop, flowshop, mixed shop and multiple identical parallel machine scheduling problems) based on the characteristics of the intricate real-life treatment processes observed at the Arden Cancer Centre in Coventry, UK. Insight into these processes was gained by developing and using a novel discrete-event simulation (DES) model of the four units of the radiotherapy department. By typifying the subproblems as well-known scheduling problem models, it was intended that methods amenable to them such as heuristics be used in the study. Four novel constructive heuristics based on priority dispatching rules and strategies adapted from some established algorithms have been developed and implemented using the C++ programming language. Further, these heuristics were incorporated into the DES model to create schedules of appointments for the patients generated daily. The effectiveness and efficiency of the constructive heuristics have been tested using the following performance criteria: minimising i) average waiting time to the start of treatment, and ii) average percentage of patients late for their treatment, and iii) the amount of overtime slots used for the patients received in a given period of time. The coordinated constructive heuristics and the DES model have also been tested using possible alternative pathways patients can follow in the treatment unit. The aim of these tests was to compare the efficiency of the radiotherapy department’s current pathway to other possible pathways. Further, strategies for using maximum allowed breaches of targeted due dates, reserved slots for critical treatments and overtime slots was also included in the heuristics. The results of several tests showed that the heuristics created schedules of appointments whose average waiting times for emergency, palliative and radical treatments improved by about 50%, 34% and 41%, respectively, compared to the historical data. However, their major slack was evidenced by the fact that about 13% of the patients needing palliative treatment were expected to be late for treatment compared to about 1% of those requiring radical treatment.

The lateral penumbra of a proton pencil beam scanning system (PBS) is of great importance in sparing of organs at risk and normal tissue when treating patients. The purpose of this current work is to measure the lateral penumbra of the Ion Beam Applications (Ion Beam Applications, Louvain‐la‐Neuve, Belgium) ProteusPLUS PBS Proton Therapy System and compare the measurements with the computed results from the RayStation proton treatment planning system. The lateral penumbra (80%-20%) was measured using EBT-3 Gafchromic film in the water tank. The lateral penumbra was studied for various parameters such as range, depth, and air gap. The computed lateral penumbra was found to be higher than the measured lateral penumbra by up to 2.3 mm in the case of depth dependency at 30 cm, and lower by up to 1.18 mm in the case of an air gap of 15 cm. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

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

Thesis (M.Sc.). / Written for the Medical Physics Unit. Title from title page of PDF (viewed 2008/07/29). Includes bibliographical references.

Thesis (M.S.)--Medical University of Ohio, 2005. / "In partial fulfillment of the requirements for the degree of Master of Science in Biomedical Sciences." Major advisor: E. Ishmael Parsai. Includes abstract. Document formatted into pages: 144 p. Title from title page of PDF document. Title at ETD Web site: Development of Graphical User Interfaces (GUI) software and databases for radiation therapy applications. Bibliography: page 65.

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

<p>One of the most used irradiation techniques in modern radiation therapy is step-and-shoot IMRT. The accuracy of this technique when delivering complex dose distributions strongly depends on the size of the subfields. The aims of this study is to determine the minimum size of subfields that can be used efficiently in Step-and-Shoot IMRT, to investigate the validation process for beam delivery and treatment planning dose calculations, and to find recommendations for practical clinical implementations.</p><p>Two different detectors, a CC04 ion chamber and a SFD stereotactic diode, have been used for measuring head scatter factors in air (Sc), total output factors (Scp) and dose profiles in water for a wide range of field sizes. The measurements were compared to calculations done with a pre-release version of the Nucletron MasterPlanTM v 3.1 treatment planning system that employs a novel, high resolution fluence modelling for both its pencil beam and collapsed cone dose calculation algorithms. Collimator settings were explicitly checked using FWHM film measurements with a build-up sheet of tungsten placed close to the treatment head to reduce the influence from lateral electron transport and geometrical penumbra. An analysis of the influence and sensitivity of Scp for small fields with respect to the linear accelerator source size and shape was also made.</p><p>The measurements with the ionization chamber and the stereotactic diode showed good agreements with each other and with the treatment planning system calculations for field sizes larger than 2×2 cm2. For small field sizes, measurements with different detectors yielded different results. Calculations showed agreements with measurements with the smallest detector, provided careful field size calibration and commissioning of calculation parameters. Uncertainties in collimator settings and source characteristics were shown to yield large uncertainties in Scp for fields smaller than 2×2 cm2.</p><p>The treatment planning system was found to properly handle small subfields but results were very sensitive to uncertainties in source size, as well as calibration and reproducibility of the collimator settings. Therefore if subfields smaller than 2×2 cm2 are to be used in IMRT extra care should be taken to determine the source characteristics and to calibrate the collimators. The volume of the detectors used for validation of such small fields and the loss of charged particle equilibrium conditions also have to be taken into consideration.</p>