The present invention relates to a link that connects it to the X-ray shielding plate do not interfere with each of the movable area, any mechanism aperture X-ray slit width can be realized and an X-ray CT apparatus equipped with the X-ray diaphragm mechanism In order to provide, X-ray shielding material 2a, and 2b, the X-ray shielding portions 2a, 2b are fixed X-ray shielding material mounting plate 3a, and 3b, the two X-ray shielding member mounting plates 3a, 3b The driven side links 5a which connects with crossed together to opposed X-ray shielding part 2a, and 2b phase, the driving link 5b, X-ray shielding member mounting plates 3a, 3b of each of the driven link 5a, the driving link and a connecting portion 13b which connects the 5b, 30b, 13a, and 30a, a drive unit 12 for the driving link 5b is driven to rotate the. Connecting portions 30a, 30b are driven link 5a, X-ray shielding material mounting plate 3a occurring in association with the rotation of the driving-side link 5b, is provided in a position that does not interfere with the movement area of 3b. With the rotation of the driving-side link 5b X-ray shielding member mounting plates 3a, 3b is moved to change the X-ray shielding material 2a, the slit width of 2b.本発明は、X線遮蔽板とそれを結合しているリンクがそれぞれの可動領域で干渉せず、任意のスリット幅を実現できるX線絞り機構及びそのX線絞り機構を搭載したX線CT装置を提供するために、X線遮蔽材2a、2bと、当該X線遮蔽部2a、2bが固定されたX線遮蔽材取付け板3a、3bと、前記二つのX線遮蔽材取付け板3a、3bを、X線遮蔽部2a、2bを相対峙させるとともに交差させて連結する従動側リンク5a、駆動側リンク5bと、X線遮蔽材取付け板3a、3bの各々と従動側リンク5a、駆動側リンク5bとを連結する連結部13b、30b、13a、30aと、駆動側リンク5bを回転駆動する駆動装置12と、を備える。連結部30a、30bは、従動側リンク5a、駆動側リンク5bの回転駆動に連動して生じるX線遮蔽材取付け板3a、3bの移動領域に干渉しない位置に備えられる。駆動側リンク5bの回転駆動に伴ってX線遮蔽材取付け板3a、3bが移動して、X線遮蔽材2a、2bのスリット幅を変更する。
