A medical imaging system, comprising: a C-type fluoroscopy device, C-arm, comprising an X-ray source and a detector, a first plate installed on an X-ray path between the X-ray source and the detector, a second plate installed on an X-ray path between the X-ray source and the detector, a reference optical marker configured to provide a 3D reference coordinate system, an optical tracking device, and a matcher, characterized in that the first plate comprises a first transmissive surface provided with a plurality of first ball markers blocking an X-ray, and a first optical marker used by the matcher for calculating locations of the plurality of first ball markers on the first plate; the second plate comprises a second transmissive surface provided with a plurality of second ball markers blocking an X-ray, and a second optical marker used by the matcher for calculating locations of the plurality of second ball markers on the second plate; the optical tracking device is configured to recognize locations of the first and second optical markers (22, 23) and the reference optical marker; and the matcher is configured to calculate a matching relationship between coordinates on the 3D reference coordinate system and locations on a first captured image and a second captured image, based on the first captured image and the second captured image that are respectively obtained by the detector with regard to a subject while the C-arm source and the detector are located at a first location and a second location, locations of the first and second ball markers on the first and second captured images, and location information obtained by the optical tracking device. a C-type fluoroscopy device, C-arm, comprising an X-ray source and a detector, a first plate installed on an X-ray path between the X-ray source and the detector, a second plate installed on an X-ray path between the X-ray source and the detector, a reference optical marker configured to provide a 3D reference coordinate system, an optical tracking device, and a matcher, characterized in that the first plate comprises a first transmissive surface provided with a plurality of first ball markers blocking an X-ray, and a first optical marker used by the matcher for calculating locations of the plurality of first ball markers on the first plate; the second plate comprises a second transmissive surface provided with a plurality of second ball markers blocking an X-ray, and a second optical marker used by the matcher for calculating locations of the plurality of second ball markers on the second plate; the optical tracking device is configured to recognize locations of the first and second optical markers (22, 23) and the reference optical marker; and the matcher is configured to calculate a matching relationship between coordinates on the 3D reference coordinate system and locations on a first captured image and a second captured image, based on the first captured image and the second captured image that are respectively obtained by the detector with regard to a subject while the C-arm source and the detector are located at a first location and a second location, locations of the first and second ball markers on the first and second captured images, and location information obtained by the optical tracking device.