Multi-leaf collimator and a radiotherapy unit provided with the same

A radiotherapy unit comprising:

• a radiation source for irradiating radiation;
• a bed on which to place an object;
• and
• a multi-leaf collimator between said radiation source and said bed, narrowing a radiation field to a predetermined shape, said multi-leaf collimator comprising:
• leaf blocks movable in the direction of the radiation field and having pattern images;
• acquisition part acquiring said pattern images;
• and
• detection part detecting the displacement or locations of said leaf blocks based on said acquired pattern images.

A radiotherapy unit comprising:

• a radiation source for irradiating radiation;
• a bed on which to place an object;
• and
• a multi-leaf collimator between said radiation source and said bed, narrowing a radiation field to a predetermined shape, said multi-leaf collimator comprising:
• leaf blocks movable in the direction of the radiation field and having pattern images drawn along the direction of movement on a predetermined surface;
• and
• detection part acquiring an image of fixed-point via fixed-point observation in the direction of said predetermined surface and detecting displacement of said leaf blocks based on the arranged locations of said pattern images existing in this image of fixed-point.

A radiotherapy unit comprising:

• a radiation source for irradiating radiation;
• a bed on which to place an object;
• and
• a multi-leaf collimator between said radiation source and said bed, narrowing a radiation field to a predetermined shape, said multi-leaf collimator comprising:
• leaf blocks movable in the direction of the radiation field and having pattern images drawn along the direction of movement on a predetermined surface;
• and
• detection part acquiring an image of fixed-point via fixed-point observation in the direction of said predetermined surface and detecting displacement of said leaf blocks based on the arranged locations of said pattern images existing in this image of fixed-point.