Fig. 3
From: Correlating preoperative imaging with intraoperative fluoroscopy in iliosacral screw placement
Preoperative CT scan with sagittal reconstruction at the midline demonstrating the anticipated outlet measurement. The horizontal line parallels the surface the patient is lying on. The oblique line overlaps the superior aspect of the symphysis pubis to the S2 body. The line at 90° simulates a straight up and down position of the C-arm. The anticipated outlet angle, labeled α, would therefore be 52° (90°−38°) of caudal tilt of the C-arm