Patent Number: 
Section: claims

1. An X-ray collimator of a computed tomography system, wherein the X-ray collimator comprises a plurality of first plates extending in the circumferential direction of the computed tomography system and a plurality of second plates extending in the axial direction of the computed tomography system; the first plates and the second plates are inserted and engaged with each other; each of the first plates is provided with a plurality of first slits spaced apart in a circumferential direction, and each of the second plates is provided with a plurality of second slits spaced apart in an axial direction,the height of the first slit is larger than half of the entire height of the first plate or the height of the second slit is larger than half of the entire height of the second plate, andtwo adjacent first plates and two adjacent second plates define a through hole, and extensions of all of side walls of the through hole intersect at a focal spot of an X-ray source, so that X-rays can pass through the through hole in a straight line;wherein the X-ray collimator further comprises a positioning plate, the positioning plate is provided with a plurality of positioning grooves extending in the circumferential direction, and each of the positioning grooves is engaged with and positioned relative to an upper end of a corresponding first plate for further positioning;each of the positioning grooves is a run-through groove; andeach of the positioning grooves comprises two or more sub-grooves spaced apart in the circumferential direction, and a solid portion between two adjacent sub-grooves is set to have a predetermined width, and the upper end of each first plate is provided with a notch for accommodating the solid portion. 2. The X-ray collimator according to claim 1, wherein the cross joints of the first slits and the second slits are positioned by adhesive bonding or welding. 3. The X-ray collimator according to claim 1, wherein a first guard plate is provided at each of two ends of each first plate, and a second guard plate is provided at each of two ends of each second plate, and the first guard plates and the second guard plates enclose the ends of the first plates and the second plates respectively. 4. The X-ray collimator according to claim 3, wherein the thickness of the first guard plate is substantially half of the thickness of the second plate, and the thickness of the second guard plate is substantially half of the thickness of the first plate. 5. A computed tomography system, comprising an X-ray detector and an X-ray collimator for collimating X-rays radiating to the X-ray detector, wherein the X-ray collimator comprises a plurality of first plates extending in a circumferential direction of the computed tomography system and a plurality of second plates extending in an axial direction of the computed tomography system; the first plates and the second plates are inserted and engaged; each of the first plates is provided with a plurality of first slits spaced apart in the circumferential direction, and each of the second plates is provided with a plurality of second slits spaced apart in the axial direction,the height of the first slit is larger than half of the entire height of the first plate; or the height of the second slit is larger than half of the entire height of the second plate,two adjacent first plates and two adjacent second plates define a through hole, and extensions of all of side walls of the through hole intersect at a focal spot of an X-ray source, so that X-rays can pass through the through hole in a straight line;wherein the X-ray collimator further comprises a positioning plate, the positioning plate is provided with a plurality of positioning grooves extending in the circumferential direction, and each of the positioning grooves is engaged with and positioned relative to an upper end of a corresponding first plate for further positioning;each of the positioning grooves is a run-through groove; andeach of the positioning grooves comprises two or more sub-grooves spaced apart in the circumferential direction, and a solid portion between two adjacent sub-grooves is set to have a predetermined width, and the upper end of each first plate is provided with a notch for accommodating the solid portion. 6. The computed tomography system according to claim 5, wherein the X-ray collimator is mounted on the X-ray detector, and each through hole corresponds to a detecting unit of the X-ray detector; a plurality of partition grooves are provided in partition regions between pixels of the X-ray detector, and the lower end of the first plate is embedded into the partition groove. 7. The X-ray collimator according to claim 1, wherein the height of the first slit is lower than 5 mm or the height of the second slit is lower than 5 mm. 8. The computed tomography system according to claim 5, wherein the height of the first slit is lower than 5 mm or the height of the second slit is lower than 5 mm.