Table 2. CRW and MidACPC coordinates obtained from iPlan stereotactic planning software. The Euclidean error in computation of the target point as compared to the point provided by iPlan using 3-points are 0.13 mm and 0.06 mm on the right and left, respectively. The Euclidean error using a 5-point least-squares computation for targets as compared to iPlan are 0.042 mm on both sides. The Euclidean distance from AC to PC was 24.45 mm and half of the value was 12.23 mm, which matched the value provided by the planning system in MidACPC space. Of note, the CRW ring angle is offset by 90 degrees.

iPlan Stereotaxy 3.0 (Brainlab, Inc., Feldkirchen, Germany)

MidACPC = Middle of Anterior Commissure and Posterior Commissure; CRW = Cosman-Roberts-Wells; AP = Antero-Posterior; LAT = Lateral; VERT = Vertical; STN = Subthalamic Nucleus; AC = Anterior Commissure; PC = Posterior Commissure.

CRW	AP	LAT	VERT
AC CRW	14.2	2.9	2.4
PC CRW	-10.1	2.1	5
Mid-Falx CRW	9.3	5.9	54.2
Right CRW Target from Planning Station	-1.8	13.6	0.3
Left CRW Target from Planning System	-0.8	-9.3	1.7
Right CRW Target from Planning Station	-1.8	13.6	0.3
Left CRW Target from Planning System	-0.8	-9.3	1.7
MidACPC	AP	LAT	VERT
AC MidACPC	12.23	0	0
PC MidACPC	-12.23	0	0
Mid-Falx MidACPC	1.98	0	51.09
Right STN Target MidACPC	-3	11.5	-3
Left STN Target	-3	-11.5	-3
Computed Data - 3 Points	AP	LAT	VERT
Right CRW Computed Target	-1.69673	13.67524	0.334593
Left CRW Computed Target	-0.79024	-9.26333	1.748831
Computed Data - 5 Points	AP	LAT	VERT
Right CRW Computed Target	-1.77279	13.62566	0.318858
Left CRW Computed Target	-0.77279	-9.27434	1.718858
CRW Angles	Ring Angle	Arc Angle	Coronal/Lat Angle	Sagittal/AP Angle
Right	51.8	20.5	20.5	38.2
Left	51.6	10.1	-10.1	38.4
MidACPC Angles	Coronal/LAT Angle	Sagittal/AP Angle
Right	19.0642	32.02104
Left	-16.7686	32.44535