Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Medical Biophysics


Dr. Eugene Wong

Second Advisor

Dr. Jeff Chen

Third Advisor

Prof. Jake VanDyk


Intensity modulated arc therapy (IMAT) is a radiation therapy technique whereby the shape of the cone beam of radiation changes as it rotates around the patient. This is in contrast to other more commonly delivered forms of advanced radiation therapy, Intensity Modulated Radiation Therapy (IMRT) or helical tomotherapy. IMRT is a radiation technique where a patient is treated with a cone beam of radiation from a number of fixed beam directions, where the shapes and weights of the radiation beams are varied and tomotherapy is treated with a fan beam of radiation that follows a helical trajectory. In this thesis two aspects of IMAT were investigated: optimization of treatment plans and delivery of plans in conjunction with and without respiratory motion management. Optimization of IMAT deliveries consisted of two studies. In the first study, an algorithm that uses dosimetric ray tracing to set multi-leaf collimator (MLC) positions then directly optimizes the MLC positions to create IMAT treatment plans with only beam shape variations was developed and tested in three phantom studies and a clinical case. The second study investigated variable angular dose rate deliveries to a concave target and assessed the optimization strategy including arc initialization strategy, angular sampling and delivery efficiency. IMAT delivery with and without respiratory gated radiation delivery was studied with dose measurement using radiographie film in a motion phantom. In addition, simulations based on delivered log files were used to confirm that motion management for IMAT is effective and within iii dosimetric tolerances. As a pilot test, plans from IMRT and tomotherapy for partial breast irradiation were first studied, comparing them to conventional treatments. An IMAT plan was generated for one patient, demonstrating feasibility and was compared with IMRT and tomotherapy. This thesis has introduced a new IMAT optimization algorithm with and without variable angular dose rate, applied to partial breast treatment, and verified its delivery under motion and gating conditions.



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