Augmented reality visualization for postmortem analysis of a traffic accident: clarification of injury mechanism through PMCT-based antemortem posture reconstruction

A man in his 80s was found lying at the roadside and later confirmed dead at a hospital. Subsequent investigation suggested that the deceased might have been struck by a car. Inspection of the suspect vehicle revealed a bent at the left front bumper, and the lower part of the left front light was found to be covered with the deceased's hair and sebum. Postmortem computed tomography (PMCT) and autopsy findings suggested that the deceased may have been struck by the vehicle from the right side first, given the severe damage to the right side of the body, including abrasions, the right chest bruising, and multiple fractures of the right ribs. To clarify the mechanism of injury, a 3D model of the bones arranged in three postures, including standing, prone and crouching patterns created from PMCT data, was fitted to a car of the same model as the suspect vehicle using augmented reality (AR). This revealed that the lower part of the left frontal light, where the victim's hair and sebum had been found, matched the location of the skull fracture if the victim had been in a crouching posture. Moreover, in this posture, the location of the right rib fracture coincided with the left front part of the car. Therefore, the deceased was most likely initially struck by the car from the right side when in a crouching position. AR visualization using PMCT-based antemortem posture reconstruction may facilitate detailed simulation of the injury mechanism and reconstruction of the scene.