A novel laser guidance system for alignment of linear surgical tools: Its principles and performance evaluation as a man–machine system

A novel laser guidance system that uses dual laser beam shooters for the alignment of linear surgical tools is presented. In the proposed system, the intersection of two laser planes generated by dual laser shooters placed at two fixed locations defines the straight insertion path of a surgical tool. The guidance information is directly projected onto the patient and the surgical tool. Our assumption is that a linear surgical tool has cylindrical shape or that a cylindrical sleeve is attached to the tool so that the sleeve and tool axes are aligned. The guidance procedure is formulated mainly using the property that the two laser planes are projected as two parallel straight lines onto the cylindrical tool surface if and only if the cylinder axis direction is the same as the direction of the intersection of the two laser planes. Unlike conventional augmented reality systems, the proposed system does not require the wearing of glasses or mirrors to be placed between the surgeon and patient. In our experiments, a surgeon used the system to align wires according to the alignment procedure, and the overall accuracy and alignment time were evaluated. The evaluations were considered not to be simply of a mechanical system but of a man–machine system, since the performance depends on both the system accuracy and the surgeon’s perceptual ability. The evaluations showed the system to be highly effective in providing linear alignment assistance.