Forensic 3D printing from micro-CT for court use- process validation

Forensic application of 3D scanning and printing technology is gaining momentum with 3D printed evidence starting to be produced for court. However, the processes for creating these forensic 3D models requires still rigorous assessment to ensure they adhere to the relevant legal standards. Although, previous work has examined the accuracy of 3D prints created from medical grade Computed Tomography (CT), no such assessment has been carried out for Micro Computed Tomography (micro-CT) which offers superior resolution and the ability to capture forensically relevant injuries. This study aimed to quantify the error rates associated with forensic 3D printed models and toolmarks, created using three different printing technologies, based on micro-CT data. Overall, 3D printed models, based on micro-CT scans, replicate bone surface geometry to sub-millimetre accuracy (<0.62mm for overall shape and <0.36mm for toolmarks). However, there were significant differences between the printing technology employed (mean errors of -0.3%, -0.8%, and 0.7% for shape geometry and -0.8%, 14.1%, and 0.7% for toolmark geometry for Printers 1-3 respectively). Where possible, the authors recommend micro-CT imaging for producing forensic 3D printed bone models particularly when injuries are present.