Development of magnetic resonance image guided radiotherapy

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Radiotherapy (RT) remains an effective treatment for both primary and metastatic cancers. Modern treatments deliver radiation under image guidance. This enables better control on dose placement, allowing dose escalation to tumours whilst reducing side effects in nearby organs at risk. The current standard of care is a single set of planning scans, followed by several weeks of RT.In radiation oncology, magnetic resonance imaging (MRI) is used to obtain exquisite non-invasive images of soft tissues. However, fundamental uncertainties inaccuracies between planning and treatment, motion during the treatment itself, and inevitable changes in tumour size over several weeks ultimately limit RT precision and accuracy. Potential overtreatment of normal tissue or under-dosing of tumour are possible, which can harm patient quality of life and survival.This proposal describes a broad research program in which we will develop the novel MRI technologies necessary to guide and adapt RT delivery. We aim to do this using a recently developed advanced image-guided RT platform called the MRI-LINAC, which integrates an external beam linear accelerator with a diagnostic 1.5T MRI scanner. The combination of these two technologies is synergistic: imaging during treatment (referred to as “beam-on”) enables adaptive tumour tracking, and the ability to treat and then image function allows the doctor to quickly assess response to treatment.Our short term objectives are (1) development of real-time beam-on imaging for adaptive RT, (2) optimization of MR-only treatment simulation, (3) advances for in vivo, MR-based dosimetry, and (4) integration of molecular imaging for treatment response monitoring. The combination of these streams aims to improve the value of MRI in radiation oncology, in the diverse areas of planning, delivery, and response assessment. In the long run, the ability to visualize tumours and their response will revolutionize the way in which RT is clinically used, but the technical advances to make this a reality have not yet been developed.The aim of this work is to develop the fundamental techniques in MR-guided RT which underlie eventual clinical applications. These techniques span the entire range of MR technology from pulse sequences to hardware, and are anticipated to have wide-ranging implications not only within oncology, but also within both diagnostic as well as interventional radiology. We also anticipate significant commercial potential arising from hardware development aspects of our program.