<title>Comparison of application accuracy of frame-based and frameless surgical localization systems and affecting factors</title>

Abstract

We compare the application accuracy of using semi-invasive fiducial markers to the Zamorano-Dujovny stereotactic ring for interactive localization of intracranial lesions. A phantom was mounted with the standard ring and also implanted with a frameless marker system which randomly distributed markers on the surface of the phantom. The target point was digitized and the coordinates were recorded and compared with reference points. Nineteen patients with intracranial lesions, chosen in random fashion, underwent a frameless stereotactic approach for tumor resection. Five semi-invasive markers were placed on the patients' skulls under local anesthesia. The coordinate of each fiducial marker was recorded in a file as the reference. The tip of each semi-invasive fiducial marker was digitized to achieve a frameless transformation matrix, and the special points on the A Zamorano-Dujovny ring were digitized to achieve a frame-based transformation matrix. The differences from the reference points were used as the deviation from the 'true point'. The mean square root was calculated to show the sum of vectors. A paired t-test was used to analyze results. The results of the phantom showed that the registration error of the frame-based system was 3.42 +/- 0.22 mm and in the frameless system was 1.01 +/- 0.63 mm. The mean showed that the mean square root of the frame-based system as 3.77 +/- 2.16 mm and of the frameless system was 2.25 +/- 1.75 mm. These preliminary results showed that the frameless semi- invasive fiducial can provide more accurate localization for may procedures. The motion of the ring after computed tomographic scan is the main reason for the errors in the frame-based system.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.