Patent ID: 7916840

Claim:
A radiation diaphragm apparatus placed between a radiation source and an object to be examined and adapted to form a radiation field, which is an exposed area of the object to be examined by radiation from the radiation source, the apparatus comprising: a plurality of diaphragm elements arranged in a first direction and movable along a second direction different from the first direction, wherein each of the diaphragm elements includes a hole of a predetermined shape formed to penetrate through it in the first direction; a first support unit which includes a shaft penetrating through the hole of each of the diaphragm elements and a bush that has a wear-resistant surface and coats the shaft, the bush rotating about an axis of the shaft so that contact points between the wear-resistant surface of the bush and a periphery of the hole vary as each of the diaphragm elements translates in the second direction; and a moving unit which moves each of the diaphragm elements along the second direction to form the radiation field.