Comparing volumetric modulated arc therapy to intensity modulated radiation therapy for the treatment of early stage prostate cancer

Research Doctorate - Doctor of Philosophy (PhD)A series of five studies are presented that when pieced together describe the transition from an innovative concept through to the clinical implementation of the radiation therapy treatment technique, Volumetric Modulated Arc Therapy (VMAT) for the treatment of early stage prostate cancer. At the outset of the research, Intensity Modulated Radiation Therapy (IMRT) was the standard modality for the treatment of early stage prostate cancer at Fraser Valley Centre (FVC). The initial studies of this research retrospectively compared IMRT to the innovative VMAT technique, specifically examining the quality of the plans produced and the impact of each technique on the departments planning and treatment resources. It was demonstrated that VMAT offered a treatment plan of similar quality to the IMRT technique yet VMAT had the definite advantage of being able to deliver treatment in significantly less time and also required significantly fewer monitor units to deliver a treatment fraction. Having demonstrated an advantage of using VMAT, it was next investigated which VMAT beam arrangement would be best suited for the treatment of early stage prostate cancer. Four VMAT beam arrangements were considered; and ultimately it was decided that for FVC VMAT using one arc provided the best compromise between plan quality and delivery efficiency. The increased complexity of VMAT planning and treatment dictates that patient specific quality assurance (QA) is required to ensure accurate dose delivery. A section of this thesis is dedicated to considering VMAT plan QA. The final study presented here compares the acute side effects experienced by patients being treated with either IMRT or VMAT. VMAT has not only been demonstrated to be a safe alternative to IMRT for the treatment of early stage prostate cancer, in a world first VMAT has also been demonstrated to significantly reduce the incidence of the acute toxicities dermatitis, fatigue, pain and urinary frequency during treatment compared to IMRT