This invention relates to a patient immobilisation assembly for immobilising at least part of a patient, the immobilisation assembly comprising a mask (1) made of a thermoplastic material, a fixation plate (3, 12, 13) and connecting means (10, 11, 14, 15, 16) for connecting the mask (1) to the fixation plate (3, 12, 13) in view of fixing the position of the mask with respect to the fixation plate, the mask being provided to cover at least partly the part of the patient to be immobilised. The mask (1) is provided to exert a pre-determined force to the part of the patient to be immobilised in view of pulling this part of the patient towards the fixation plate (3, 12, 13) and of restraining the movability of the part of the patient to be immobilised within the mask. <；IMAGE>；
