Patent Number: 
Section: claims

1. Collimator for radio surgery or radio therapy comprisinga plurality of leaves;guiding members for guiding a movement of the leaves;a pressing unit for causing a press contact between the leaves and the guiding members;wherein the pressing unit comprises pressing members which are at least configured to allow for a rolling press contact between the pressing members and the leaves. 2. Collimator according to claim 1, wherein the pressing member is a rolling member. 3. Collimator according to claim 2, further comprising a holding member for holding the rolling members at predetermined positions. 4. Collimator according to claim 1, wherein the pressing unit is configured to further allow for a frictional contact between the rolling members and the leaves. 5. Collimator according to claim 3, wherein the holding member comprises an accommodating part which comprises cavities for accommodating the pressing members at predetermined positions. 6. Collimator according to claim 1, wherein the pressing unit comprises an elastic unit for pressing the pressing members towards the leaves. 7. Collimator according to claim 6, wherein the elastic unit comprises a spring unit having a plurality of spring fingers extending at least substantially perpendicular to a direction of the pressing performed by the pressing unit. 8. Collimator according to claim 7, wherein the spring fingers extend at least substantially parallel to the direction of movement of the leaves. 9. Collimator according to claim 7, wherein the spring unit comprises a connecting frame or connecting base which connects at least a part of the spring feed fingers with each other. 10. Collimator according to claim 7, wherein the spring fingers are arranged in two groups, one group extending at least substantially in the same direction as the movement of the leaves, the other extending at least substantially in the direction opposite to the direction of the movement of the leaves, said extension of the spring fingers respectively origins from the connecting base or connecting frame. 11. Collimator according to claim 7, wherein the spring unit is sheet-like. 12. Collimator according to claim 7, wherein the pressing unit further comprises support members for defining a pressing strength by supporting at least part of the spring fingers. 13. Collimator according to claim 1, wherein a radiation resistant lubricant is provided between at least one of the following: the leaves and the guiding members, and the leaves and the pressing members. 14. Collimator according to claim 1, wherein the edges of at least one of the lengthwise ends of the guiding members comprise chamfers. 15. Collimator according to claim 1, wherein at least one of the guiding members and edges of the leaves which contact the guiding members have been subjected to a surface hardening process. 16. Collimator for radio surgery or radio therapy comprisinga plurality of leaves;guiding members for guiding a movement of the leaves;pressing members for causing a press contact between the leaves and the guiding members;wherein a radiation resistant lubricant is provided between at least one of the following: the leaves and the guiding members, and the leaves and the pressing members.