Identification of unknown dead bodies by X-ray image comparison of the skull using the X-ray simulation program FoXSIS

The aim of the study was to improve the objectivity of X-ray image comparison for the identification of unknown dead individuals. CT-data were collected for 30 macerated skulls. An already presented computer program which uses CT data to establish virtual X-ray images was used to obtain X-rays with different beam angulations simulating rotation, dorsal flexion, and ventral flexion. Specific parameters were measured on the simulated images. The frontal sinus reveals the highest variability not only between the individual skulls but also within an individual skull in different positions. The most consistent parameters with respect to different positions were the skull breadth, the biorbital breadth and the bizygomatic breadth. In a blind study, three out of 24 skulls could clearly be identified just by measured distances although the positions were different and unknown to the investigator. The dimensions of the frontal sinus do not correlate with the other skull parameters (analysis of covariance). Based on the presented results, we propose a method that will calculate the probability of identity. The presented results demonstrate that the comparison of X-ray images can be undertaken in an objective way by quantifying the probability of identity even when the comparative images were made under different conditions.