The present invention describes a frame (1) for securing a thermoplastic mask (2) suitable for the portable coil of a nuclear magnetic resonance apparatus and for a computerized tomography apparatus, which comprises a first support portion (1a) for the upper part of the patients back and a second support portion (1b) for securing the patients head in an upright position, the two support portions (1a, 1b) comprising means (3a, 3b) for anchoring the thermoplastic mask (2) and the anchoring means (3b) of the second support portion (1b) securing the thermoplastic mask (2) behind the patients head.
