IGS is a system developed to define a specific point during surgery in a two- or three-dimensional view of a patient's anatomy. A preoperative CT scan or MRI is performed, and the data is loaded on a high-power computer and projected on a screen in the operating room during surgery. The components for this system include a camera to pick up a signal from a probe connected to a computer, which has been loaded with the patient's scan results. A high-resolution monitor allows projection of all this information. An interactive line in the OR is usually linked to the Radiology Department so the patient's scans can be easily loaded on to the system.

The IGS machine uses this information to show a three-dimensional view of the diseased area. A probe with diodes is on the sterile field and connected to the system. The surgeon navigates the area, finds distinct marks in the patient's anatomy, numbers those points, and inputs their location to the system. The points are "picked" using the probe to touch the exact location. This is called registration. The system then automatically calculates registration errors in millimeters. Any deviation of more than 2 mm registration should be redone.

This technology helps to determine length, width, and depths of hardware placement in spine surgery and to gauge the precise placement of instruments around delicate structures. For multilevel spine procedures, registration points are picked for every level.

Before a surgical procedure, the instrument is brought to the room to make sure that the IGS MRI or CT scan results are loaded onto the system. The camera is placed to pick up the signal from the probe without compromising the sterility of the surgical area. With the use of stereotactic image-guided surgery, there is less exposure to radiation and reduced surgery time, thus producing better patient outcomes.

Neurologic application was the first in IGS application, with spine right behind. Other orthopaedic applications and some ENT procedures are now using IGS.