| 摘要 |
An apparatus for limiting an irradiation field includes aperture leaves arranged in a width direction thereof, the aperture leaves being controlled to be unmovable in the width direction and movable in a driving direction substantially perpendicular to the width direction. The apparatus causes the aperture leaves to block radiations emitted by a source so as to provide a desired irradiation area. At least one aperture leaf is a supporting aperture leaf having a groove at a periphery thereof. The apparatus includes a linear member, one end of which is secured to the periphery of the supporting aperture leaf and the linear member engages with the groove. The apparatus also includes a restricting portion to hold the linear member between the restricting portion and the groove such that the supporting aperture leaf is controlled to be unmovable in the width direction and movable in the driving direction. |
