The term “frameless image-guided surgery” has become as well-known to surgeons as computerized tomography or operating room microscope over the past several years. The technoloies behind this new surgery option include robotic arms, infra-red camera arrays (1D and 2D), ultrasound, robotic microscopes and magnetic field digitizers. The authors have shown the magnetic field technology incorporated in the Regulus Navigator to be a viable, accurate surgeon's tool by first integrating a conventional framed device and magnetic field frameless device, then advancing to the frameless device alone.

During surgery a patient's anatomy is first registered to preoperatively acquired radiological data. Surgical instruments are tracked on interactive CT/MRI displays as the surgeon locates his point or volume-in-space within the surgical field and uses his own procedure/technique of choice for surgical treatment. A clinical trial of 221 patients showed an overall mean accuracy of 2.56mm with a standard deviation of 1.15mm for intraoperative registration. Major concerns of utilizing magnetic field technology in the operating room, such as interference from surrounding metallic objects and equipment, were proven manageable while maintaining acceptable accuracy.