The accuracy of topographical and shape analysis using three-dimensional surface scanning compared to Micro-Computed Tomography

Abstract

The high number of unidentified bodies recorded in South Africa annually, combined with substantial heterogeneity within the population, necessitates that innovative forensic analysis methods be developed that incorporate variations from South African groups. Although sizeable three-dimensional (3D) scanning modalities exist in osteology and anthropology, developing new advanced methods and techniques involving 3D scanning for real-life forensic applications require that the accessibility, practicality, and, more importantly, accuracy of the methods be taken into consideration. To this end, this study aimed to assess the reliability of 3D surface scanning-based topographical and shape analysis comparison to gold standard micro-focus X-ray computed tomography (micro-XCT) reconstructions for estimating population affinity.

Forty-four adult crania were collected from the Pretoria Bone Collection (PBC), University of Pretoria, South Africa. Two sets of 3D reconstructions were acquired from each cranium, namely micro-XCT scans and 3D surface scans. Three-dimensional reconstructions and landmark datasets were acquired from both scanning modalities and compared using reproducibility testing, geometric discrepancies, and shape analysis.

The minimal geometric discrepancies observed between the reconstructions suggest that both modalities will provide similar shape landmarks datasets and can be used without compromising the accuracy of the analyses at term. The statistical findings showed similar population affinity-related mid-facial shape variations analyzed across both modalities using geometric morphometric methods (GMM).

Incorporating multiple 3D scanning modalities and advanced GMM into the existing biological profile estimation will allow South African forensic anthropologists to analyze shape-related skeletal variation in a more accurate and repeatable way and provide an efficient biological profile in forensic cases.