Description of the novel device
According to Desargues’ theorem of projection geometry and the characteristics of X-ray fluoroscopic imaging, a three-axis co-linear approach (fluoroscopic center axis, target axis and laser positioning axis) is adopted. At the same time, we make use of the visualization characteristics of the laser, when the laser lines representing two planes (Desargues’ plane) cross each other, the confluence is the target channel, to realize the visualization of the three-dimensional positioning of the target channel. The laser-guiding navigation device is composed of two laser pointers (in-line, energy 100 mW, wavelength 520 nm, wavelength 635 nm, Senwei), special laser pointer holder, and locating ring attached to the G-arm’s image intensifier (G-arm Orca, WHALE MEDCINE, Boston, USA). Before operation, the device was adjusted repeatedly to ensure that the two laser lines, X-ray fluoroscopy center line and the target axis, were completely overlapped in horizontal and vertical planes simultaneously (Fig. 
Work principle sketch maps of the laser guiding navigation device (