A process for converting the beam diameter of radioactive rays and radiating unit

摘要

The present invention discloses a process for converting the beam diameter of radioactive rays and a radiating unit used in a medical stereotactic radiotherapeutic apparatus. Over a collimator carrier (11) symmetrical about a central axis are distributed a number of sets of collimators (1) of different aperture diameter. The rule of distribution of each set of collimators is the same as that of the radioactive sources (2) in the source carrier (4). The collimator carrier (11) can be rotated according to the requirement of the therapy to bring a set of collimators (1) of a certain aperture diameter in alignment with the radioactive sources (2). Thus it is possible to alter the size of the beam diameter of radioactive rays. The advantages of the invention are convenience in operation, enhancement of the accuracy of positioning and the easiness of putting into practice the automatic control by a computer.