CT-scan vs. 3D surface scanning of a skull: first considerations regarding reproducibility issues

Abstract

Three-dimensional surface scanning (3DSS) and multi-detector computed tomography (MDCT) are two techniques that are used in legal medicine for digitalizing objects, a body or body parts such as bones. While these techniques are more and more commonly employed, surprisingly little information is known about the quality rendering of digitalized three-dimensional (3D) models provided by each of them. This paper presents findings related to the measurement precision of 3D models obtained through observation of a study case, where a fractured skull reconstructed by an anthropologist was digitalized using both post-mortem imaging methods. Computed tomography (CT) scans were performed using an 8-row MDCT unit with two different slice thicknesses. The variability of 3D CT models superimposition allowed to assess the reproducibility and robustness of this digitalization technique. Furthermore, two 3D surface scans were done using a professional high resolution 3D digitizer. The comparison of 3D CT-scans with 3D surface scans by superimposition demonstrated several regions with significant differences in topology (average difference between +1.45 and −1.22 mm). When comparing the reproducibility between these two digitalizing techniques, it appeared that MDCT 3D models led in general to greater variability for measurement precision between scanned surfaces. Also, the reproducibility was better achieved with the 3D surface digitizer, showing 3D models with fewer and less pronounced differences (from +0.32 to −0.31 mm). These experiments suggest that MDCT provides less reproducible body models than 3D surface scanning. But further studies must be undertaken in order to corroborate this first impression, and possibly explain the reason for these findings.

Virtual anthropology: a preliminary test of macroscopic observation versus 3D surface scans and computed tomography (CT) scans

“…Centre universitaire romand de médecine légale, Lausanne-Genève, CURML) manages important amounts of forensic cases in Switzerland. A pioneer in the development of forensic imaging [ 7 ], CT and 3D surface scans are routinely performed at the CURML, and a series of projects on the use of CT and 3D surface scanning models in anthropology are ongoing [ 8 , 9 ]. In the research presented here, 3D models were created using both a CT scanner and a 3D surface scanner.…”

Accuracy of an automated three‐dimensional technique for the computation of femoral angles in dogs

“…Second, 3D scanner allows the user to work with real 3D files, which we cannot obtain from other reported twodimensional techniques. 9,18 It may be argued that we could have either measured the femoral angles on digital photography images of femur specimens or calculated them directly onto the bones.…”

“…The aim was to increase the visualisation of the femoral cortices, decreasing the radiotransparency of the bone and thus improving the quality of the femoral captures. Secondly, 3D scanner allows the user to work with real 3D files, which the authors cannot obtain from other reported 2D techniques 9 18 . It may be argued that the authors could have either measured the femoral angles on digital photography images of femur specimens or calculated them directly onto the bones.…”

Effective approaches to three-dimensional digital reconstruction of fragmented human skeletal remains using laser surface scanning

“…Traditional crime scene and forensic reconstruction and documentation methods are now giving way to three-dimensional (3D) imaging [ [10] , [11] , [12] , [13] ]. Methods include X-ray computed tomography (including micro-CT) [ 14 , 15 ], laser scanning [ 15 , 16 ], structured-light scanning [ 16 ], and 3D photogrammetry [ 9 , 17 ]. A number of researchers have emphasized the clear advantages to 3D digitization over other recording techniques i.e.…”

“…A number of researchers have emphasized the clear advantages to 3D digitization over other recording techniques i.e. examination of fragile and otherwise inaccessible material, the production of affordable, high-quality replicas for display, teaching, and research, increased accuracy and enhanced data sharing [ [7] , [8] , [9] , [10] , [11] , [12] , [13] , [14] , 17 , 18 ]. The use of surface scanning in forensic anthropology and medicine has been well established [ 19 ], in contexts such as the analysis of burned remains [ 20 ], replication of anthropological specimens for curation and illustration [ 20 ], recording taphonomic changes [ 21 ], evaluating trauma [ 1 , 22 ], determining bullet pathways [ 23 ], and presenting evidence in court [ [24] , [25] , [26] ].…”