OC-0685: MRI-linac-based head-and-neck radiotherapy: a new concept for optimal neck sparing

Delineation uncertainties of tumour volumes on MRI of head and neck cancer patients

“…An example of prostate cancer is very appropriate: compared to CBCT, onboard MRI can potentially reduce the daily uncertainties in identifying the interface between the posterior part of the gland and the anterior rectal wall or between the prostate apex and penile bulb. But since all the stages in treatment using MRLinac result in a quite prolonged time period, lasting approx.30 min or more, patient inclusion is still a considerable issue and not all patients can be treated despite good indications.GTV changes during a long treatment period, as well as the possibility to decrease actual delivered dose to organs at risk, may justify the use of MR Linacs for some head and neck cancer patients despite long total treatment times [12,18,46,47]; however, these aspects are outside of the scope of this paper. Moreover, guidelines and additional training are needed to improve the consistency of target delineation for the clinical introduction of adaptive radiotherapy based on MRI [19].…”