Detector for a positron emission tomography (PET)-scanning device

A detector for a positron emission tomography (PET)-scanning device, the detector comprising

• an opening sized to accommodate the head of a human patient;
• a plurality of sensor modules, which serve to detect emitted PET-radiation from the human patient and are arranged in the form of a regular polygon having a plurality of corners;
• and
• an inner surface, which is arranged radially inside of the sensor modules, in order to circumferentially delimit the opening,
• wherein the sensor modules are arranged such that one of the corners is a nose corner which is adapted to accommodate the patient's nose when the patient's head is positioned in the opening of the detector in order to be scanned by the PET-scanning device, and
• wherein the inner surface reflects the shape of the polygon at least in a region of the nose corner, and
• wherein the inner surface defines a curvature that corresponds to the incircle of the polygon in areas of one or more of the plurality of corners.