Detailed, accurate anatomical models – printing physical 3D objects from CT data
Advances in 3D printing technology have made it possible to create highly complex, three-dimensional objects based on computer models, reasonably quickly and affordably. Today’s 3D printers have sufficient resolution for accurate and detailed recreation of anatomic and other structures based on X-ray or nuclear tomography data. However, the data require manipulation and conversion to an appropriate format for use with the printer, and may need adjustments to enable creation of a stable physical structure in three dimensions.
Doney et al. present a method to print a physical 3D model based on preclinical X-ray computed tomography (CT) data, using a live rat and a preserved rabbit skull as examples. In the video and text versions of this paper, the authors discuss the equipment, software tools and steps needed to complete data collection, surface rendering, data conversion and cleanup, and printing.
The authors use a Bruker Albira imaging system and Albira Suite Reconstructor software to acquire and reconstruct a CT image with 0.125 mm isotropic voxel size. While skeletal features were printed from the raw data, soft tissue – in this example, lungs – required segmentation to define the volume of interest, again using the Albira software.
The authors next converted the data to DICOM format to obtain density values for each voxel, via PMOD software (PMOD Technologies). For printing, the volumetric data must be converted to a contiguous surface. The authors used ImageJ software to render the surface and export the results to Wavefront format. Using a combination of software tools – the open source Meshlab and the freeware Netfabb Studio Basic – the team completed stereolithographic editing to repair any gaps, remove excess mesh, and smooth the surface of the final model tools before printing. Finally, the authors compare printing materials and options with 3D printing services or a commercial desktop printer.
The authors present accurate and highly detailed plastic models of the rabbit skull, rat skeleton, and lungs in varied colors. Today’s 3D printing technology and the Albira imaging system’s fine voxel size and data handling capabilities make it possible to cost-effectively create complex, detailed, and accurate 3D models that would otherwise be impossible to reproduce. These physical models show promise as practical, hands-on visualization, research, and educational tools.
Doney E, Krumdick LA, Diener JM, Wathen CA, Chapman SE, Stamile B, Scott JE, Ravosa MJ, Avermaete TV and Leevy WM. 3D printing of preclinical x-ray computed tomographic data sets. J Vis Exp 2013;73:50250. PubMed Central: PMC3671719.