Table 8. Comparison of target localization coordinates for an electrode tip in a single case. Here, MidACPC coordinates are presented. All Euclidean distances are compared to the "gold standard" postoperative CT, including the final intraoperative image (O-arm2) and the originally planned target. RT and PP fair well relative to the post-op CT with Euclidean distances of 0.48 mm and 0.30 mm as compared to O-arm2 of 0.41 mm.

AP = Antero-Posterior; LAT = Lateral; VERT = Vertical; MidACPC = Middle of the Anterior Commissure to Posterior Commissure point; RT = Ray Tracing; PP = Perspective Projection; Rel Post-op CT = Euclidian Distance relative to the post-op CT; Rel to O-arm2 = Euclidian Distance relative to the intraoperative O-arm2; Rel to Plan Target = Euclidian Distance relative to original planned target.

	Planned Target	O-arm2	CT	RT	PP
AP	-3.5	-3.02	-3.16	-3.32	-3.43
LAT	-12	-11.15	-10.8	-10.6	-10.74
VERT	-4	-3.71	-3.88	-3.47	-3.76
Rel Post-op CT	1.252996	0.413521	0	0.483425	0.301496
Rel to O-arm2	1.018332	0	0.413521	0.670895	0.581979
Rel to Plan Target	0	1.018332	1.252996	1.507747	1.284562