Patent ID: 7965819

Claim:
An irradiation field limiting device which shields radiation from a radiation source by driving a plurality of aperture leaves a specific amount to limit an irradiation field to a desired range, the irradiation field limiting device comprising: a plurality of aperture leaves each having a circumferential shape; a driver section; and a flexible linear member, one end thereof being secured to at least one aperture leaf and the other end being connected to the driver section, the driver section being configured to drive the flexible linear member in an axial direction of the flexible linear member to cause movement of the at least one aperture leaf, wherein the aperture leaves are arranged in a thickness direction thereof adjacent to each other, the one end of the flexible linear member is secured to an inner or outer circumferential surface of the at least one aperture leaf, and the driver section drives the flexible linear member while increasing or decreasing a contact portion between the flexible linear member and the inner or outer circumferential surface of the at least one aperture leaf by warping the flexible linear member, and wherein the driver section includes: a base; a drive shaft connected with a driving source through a connection portion and inserted into the base; and a slider which moves along an axial direction of the drive shaft accompanying rotation of the drive shaft and is connected with the linear member.