Table 1.

Algorithm performance. For all five patients, the percentage of images in which each fiducial was detected, the percentage of images in which at least one fiducial was detected, the percentage of valid detections for each fiducial, the average or valid detections for each patient, and the average detection error are represented in mm. The mean detection error in the 2D images was calculated assuming an error of 0.392 mm (pixel size) for the valid detections, and the measured error with respect to the ground truth as determined by manual introduction for the bad detections.

Case	% Images with localization of the three fiducials (F1/F2/F3)	% Images with at least one fiducial detected	% Valid detections (F1/F2/F3)	Average (%)	Average detection error (mm)
1	49/60/54	86	87/92/97	92	0.6
2	57/47/51	64	99/99/99	99	0.4
3	36/29/26	40	94/91/98	94	0.6
4	39/23/41	58	94/80/91	91	0.6
5	51/65/45	95	89/96/93	93	0.5