| 摘要 |
PROBLEM TO BE SOLVED: To provide a particle beam therapy system where an irradiation field is formed precisely and easily by detecting the reference position of irradiation field formation of collimator leaves of a multi-leaf collimator precisely. SOLUTION: The system is provided with: two or more drive means for moving a pair of groups of collimator leaves and two or more collimator leaves arranged opposing at both of the side parts in the center of the irradiation field in an approaching direction or a separating direction with respect to the center of the irradiation field by each leaf; two or more position detectors; a stoppage member for carrying out positional regulation in the separating direction of the collimator leaves; and a pair of misalignment detection members for detecting misalignment of the collimator leaves. In the case of forming the irradiation field, the rear ends of the collimator leaves are moved to a position contacting with the stoppage member. Continually, moving operation of moving the respective collimator leaves to a prescribed position where the protrusions of the collimators do not abut on the misalignment detection members in the approaching direction on the center side of the irradiation field is carried out. Then, presence/absence of misalignment of the two or more collimator leaves is detected by presence/absence of abutting of the collimator leaves onto the misalignment detection members in the middle of movement. COPYRIGHT: (C)2007,JPO&INPIT
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