The invention provides an improved way of immobilizing a patient for MR-guided radiotherapy. In particular, the invention provides a head coil arrangement (300) for a magnetic resonance device (100), comprising a helmet-shaped coil housing (310) comprising at least one conductor carrier (311, 312) extending in a distance to a head supporting plane and forming in between a receiving space (313) for a patient's head. The head coil arrangement (300) further comprises a head-fixation structure (320), which is supported, via at least one leg (321), at the conductor carrier (311, 312) so as to at least partially protrude into the receiving space (313) and configured to be brought into blunt contact with the patient. Further, the invention provides a magnetic resonance device (100) comprising such a head coil arrangement (300) as well as a method of immobilizing a head within such a magnetic resonance device (100).
