Table 12. Comparison of manual selection versus automation for 3D fiducial spheres using a "center of mass" calculation. Single dimension error calculations are delta values and 3D errors are Euclidean distances. The average Euclidean error is 0.23 mm using this automation.

Sphere = Spherical Fiducial identified automatically on CT; Delta AP = Error in Antero-Posterior dimension in millimeters; Delta LAT = Error in Lateral dimension in millimeters; Delta VERT = Error in Vertical dimension in millimeters; Euclidean Error = Total Euclidean 3D error.

Sphere	Delta AP	Delta LAT	Delta VERT	Euclidean Error
1	-0.05	0.1	-0.19	0.2205
2	-0.07	0	0.27	0.2789
3	-0.01	0.03	-0.01	0.0332
4	0.05	-0.02	0.16	0.1688
5	0.13	0.13	0.17	0.2504
6	0.11	0.2	0.13	0.2627
7	0.14	0.24	0.18	0.3311
8	0.22	0.17	-0.14	0.3113
Average	0.065	0.1063	0.0712	0.2321