| 摘要 |
A positron emission tomograph is used for recording the spatial distribution of a substance radiating positrons, which substance has been inserted into a body to be examined. It has a ring arrangement, enclosing a treatment space for the body to be examined, of gamma ray detectors which record a signal in in each case one detector with the aid of a coincidence circuit with a simultaneous entry of two gamma quanta essentially flying in opposite directions and produced when a positron is irradiated with an electron. The signals produced overall are processed in an evaluating unit which generates the recording of the spatial distribution. To reduce the distance between the location of origin and the location of decay of the positrons and thus to increase the image definition, a device exists for generating a magnetic field in the treatment space in such a manner that the positrons pass through a spiral-like path in the magnetic field between their location of origin and the location of irradiation. |
