Table 1.

Summary of Tracking Errors (cohort 1)

Case #	Error	Translations Tracked	Rotations Tracked
1	A,B,D	Yes	No
2	D	Yes	No
3	A,D	Yes	No
4	C	Yes	No
5	A	Yes	No
6	A	Yes	No

A. Failure to meet the minimum distance between markers

B. Failure to meet the minimum angle requirements between markers

C. Not enough markers

D. Markers are too closely spaced on DRR for accurate fiducial extraction