Pathology - Theses
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ItemImage guided and adaptive radiotherapy for muscle invasive bladder cancer( 2014)Introduction: Bladder cancer is one of the ten most frequent cancers in Australia. It is also the only common cancer for which survival has decreased over the last twenty years. The two curative treatment options for muscle invasive bladder cancer are radical surgery requiring removal of the bladder, or radical radiotherapy (alone or in combination with chemotherapy). Radical radiotherapy allows many patients to keep their natural bladder. As a dynamic soft tissue organ, the bladder size, shape and position vary with bladder and rectal filling, requiring traditional radiotherapy fields to have large margins around the target. With conventional radiation treatment such large margins increase the risk of normal tissue side effects and yet there still remains the risk of missing the bladder cancer on some treatment fractions. Methods: I have developed an innovative technique with a new device, cone beam computed tomography to match radiation fields and volume on a daily basis to the bladder position and size. This technique reduced the margin of the radiation fields required around the bladder. I have led a number of training programs and their evaluation to teach radiation therapists to conduct such treatments. In addition to the development work, I have conducted a prospective pilot study in 27 participants, of this adaptive radiotherapy technique. Following further refinement I led the multi-centre clinical trial that established the technique as standard of care in a number of institutions. Results: I found that cone beam computer tomography was of sufficient quality to be used to match radiation fields to the bladder on a daily basis. I determined that such daily matching prior to treatment was better than an ‘offline” process where an average radiation treatment plan was created after several radiation treatments. I found in our pilot study that adaptive radiation treatment decreased surrounding normal tissue irradiation. Separate studies showed that both workshop and e-Learning based radiation therapist training increased confidence and decreased variation from the gold standard (radiation oncologist results). I conducted a number of studies examining appropriate margins for bladder cancer radiation treatment with different imaging techniques. Through a multi-centre feasibility study of 54 participants, I introduced the image guided adaptive radiotherapy technique into a number of Australia centres, and demonstrated that, while technically possible, the margin around the bladder in this protocol was too small. Conclusions: Image guided and adaptive radiotherapy is possible in many radiation therapy departments with likely benefits for patients in terms of cancer control and reduced normal tissue side effects. Through my work the technique has been established as standard of care in a number of Australian and New Zealand centres. However such radiotherapy techniques can continue to be optimised. Future phase III studies are required to conclusively prove their benefit.