Patent Number: 
Section: claims

1. Radiation therapy equipment including a radiation collimator unit for setting a desired irradiation field onto a target treating region by shielding radiation on unnecessary regions, the radiation therapy equipment comprising:a pair of movable collimator blocks, each block including a plurality of movable leaf plates, each leaf plate having a toothed configuration on an arc shaped tracking surface on the leaf plate;a plurality of driving gears configured to independently drive each of the plurality of leaf plates by engaging with the toothed configuration provided on each tracking surface of the plurality of leaf plates;a plurality of constant force spring units coupled to each of the plurality of driving gears configured to constantly apply a direct force to each of the plurality of driving gears so as to independently move each of the plurality of leaf plates in closing directions;a plurality of wires connected to each of the plurality of leaf plates; anda plurality of roll-up units configured to independently roll-up each of the plurality of wires so as to independently move each of the leaf plates in an opening direction against each of the closing forces of the plurality of constant force spring units. 2. In the radiation therapy equipment according to claim 1, wherein the radiation collimator unit comprises:a pair of upper collimator blocks provided at a near position of the radiation source, each block having a first toothed configuration on a first arc shaped tracking surface so as to move along a first moving track;a pair of driving gear units configured to drive the pair of upper collimator blocks by engaging with the toothed configurations provided on each of the tracking surfaces;a pair of lower collimator blocks provided under the pair of upper collimator blocks, each block being formed with a plurality of leaf plates, and each plate having a second toothed configuration on a second arc shaped tracking surface so as to orthogonally move crossing the first moving track;wherein each of the lower collimator blocks comprises:a plurality of driving gears configured to independently move each of the plurality of leaf plates engaging with the second toothed configuration;a plurality of constant force spring units coupled to each of the plurality of driving gears so as to independently apply a constant force in a closing direction;a plurality of wires connected to the plurality of leaf plates; anda plurality of roll-up units configured to independently roll-up the plurality of wires so as to independently move each of the plurality of leaf plates in an opening direction against the force applied by the plurality of constant force spring units. 3. The radiation therapy equipment according to claim 2, wherein each of the plurality of constant force spring units is comprised of two drums for winding up a plate spring, andeach of the plurality of constant force spring units is supported by a pair of rotation shafts; and each shaft penetrates each of center apertures of the two drums. 4. The radiation therapy equipment according to claim 3, wherein the plurality of constant force springs is supported by a plurality of pairs of rotation shafts arranged in a direction of the first arc shaped track. 5. The radiation therapy equipment according to claim 4, wherein first ones of the plurality of driving gears are coaxially supported on one pair of rotation shafts and second ones of the plurality of driving gears are coaxially supported on another pair of rotation shafts, and the first and second ones of the plurality of driving gears are arranged in staggered positions. 6. The radiation therapy equipment according to claim 3, wherein each of the plurality of driving gears engaged to each toothed configuration of the plurality of leaf plates is connected to one of the two drums forming the constant force spring. 7. The radiation therapy equipment according to claim 6, further comprising a control unit configured to independently control a moving amount of each of the leaf plates in the opening direction by each of the plurality of roll-up units so as to set an irradiation field of radiation in accordance with a position of each of the leaf plates and a target shape of a treatment region. 8. The radiation therapy equipment according to claim 1, wherein the plurality of leaf plates is respectively attached to a plurality of wires, andthe plurality of roll-up units independently roll-up the plurality of wires so as to move each of the leaf plates in an opening direction against the force of the spring unit in a closing direction. 9. The radiation therapy equipment according to claim 1, wherein each of the plurality of roll-up units includes a motor for winding up the wire so as to move the each of the leaf plates at a desired position in order to form the irradiation field. 10. The radiation therapy equipment according to claim 9, wherein each of the plurality of roll-up units winds up the wire to a corresponding one of the motors through a pulley and the plurality of roll-up units is freely installed in a space in the radiation collimator unit. 11. The radiation therapy equipment according to claim 1, further comprising a detection unit configured to detect a position or a moving amount of each of the leaf plates by a non-contacted detection of a specific pattern fixed on a tracking surface of each of the leaf plates. 12. The radiation therapy equipment according to claim 1, further comprising a magnetic sensor provided near the driving gears for acquiring detection data on a multi-pole magnetic pattern attached on a peripheral surface of the driving gear; anda moving amount of each of the plurality of leaf plates is controlled based on the detection data. 13. A radiation therapy equipment comprising:a radiation source;an upper irradiation collimator unit provided near the radiation source along an irradiation axis of the radiation source; anda lower irradiation collimator unit provided under the upper irradiation collimator unit along the irradiation axis so as to orthogonally cross a moving direction of the upper irradiation collimator unit; the upper irradiation collimator unit and the lower irradiation collimator unit are moved so as to determine an irradiation aperture for irradiating an object;wherein the lower irradiation collimator unit is comprised of:a plurality of movable leaf plates, each having a toothed configuration on one curved edge of the leaf plate;a plurality of driving gears for respectively engaging to each of the toothed configurations of the plurality of movable leaf plates;a plurality of spring units coupled to each of the plurality of driving gears for respectively applying a direct force to each of the plurality of movable leaf plates through each of the plurality of the driving gears so as to independently move in a closing direction of the irradiation aperture;a plurality of wires connected to each of the plurality of movable leaf plates; anda plurality of wire drive units configured to drive each of the plurality of wires so as to move in an opening direction of the irradiation aperture.