CT-based Ballistic Wound Path Identification and Trajectory Analysis in Anatomic Ballistic Phantoms

Purpose: To evaluate the accuracy of computed tomography (CT)-based ballistic wound path identification in phantoms by determining the agreement between actual shooting angles and both trajectory angles measured with a picture archiving and communication system (PACS) angle tool and angles calculated from x, y, z coordinates of the entrance and exit points. Materials and Methods: In this institutional review board-approved model study, two simulated legs were shot by a trained marksman from 50 yards at six clinometer-measured angles with a 0.30-06 rifle and then scanned at multidetector CT. Radiologists measured the wound path angles on paracoronal reformations by using a PACS angle tool. Observers determined the Cartesian coordinates of the entrance and exit points of the wound paths on axial CT images by using detailed instructions. Angles were calculated from these coordinates by using a computer arctangent function. Agreement between the angles was evaluated with Bland-Altman plots. Means, ranges, and standard deviations of the angles also were determined. Results: Radiologists identified all six wound paths on the CT images. The PACS tool-based measured and coordinate-based calculated angles were within 5 degrees of the shooting angles. Results indicated that in larger study populations, one can be 91% confident that future coordinate-based angle calculations will differ from the actual shooting angle by no more than 5 degrees and 95% confident that PACS tool-based angle measurements will differ from the actual shooting angles by no more than 4.5 degrees. One can be 95% confident that future coordinate-based angle calculations will differ from PACS angle measurements by no more than 4.02 degrees. Conclusion: Study results demonstrated the feasibility of consistent wound path identification and the accuracy of trajectory angle determination in models with use of multidetector CT.