Dosimetry needs for MRI-linacs

The pursuit of real-time image-guided radiotherapy has prompted the development of hybrid devices coupling MRI scanners with radiotherapy treatment units, usually linear accelerators (linacs). One of the challenges in MRI-linac technology is the magnetic field impact on the dose deposition. Dose deposition effects have to be considered in the radiation therapy chain as they alter the dose distribution in patients and influence the response of many commonly used radiation detectors. In this presentation specific issues of dosimetry for MRI-linacs will be reviewed and illustrated with examples from the Australian MRI-linac commissioning process.