Characterization of 3-Dimensional Printing and Casting Materials for use in Computed Tomography and X-ray Imaging Phantoms
Bryan E. Yunker, Andrew Holmgren, Karl F. Stupic, J. L. Wagner, S Huddle, R Shandas, R. F. Weir, Kathryn E. Keenan, Edward J. Garboczi, Stephen E. Russek
Imaging phantoms are used to calibrate and validate the performance of medical computed tomography (CT) systems. Many new materials developed for three-dimensional (3D) printing processes may be useful in the direct printing or casting of biomimetic and geometrically accurate CT and X-ray phantoms. The X-ray linear attenuation coefficients of polymer samples were measured to discover materials for use as tissue mimics in phantoms. This study included a cohort of polymer compounds that were tested in cured form. The cohort consisted of 101 standardized polymer samples fabricated from: two-part silicones and polyurethanes used in commercial casting processes; one-part optically cured polyurethanes used in 3D printing; and fused deposition thermoplastics used in 3D printing. The testing was performed with a commercial micro-CT imaging system from 40 kVp to 140 kVp. The X-ray linear coefficients of the samples and human tissues were plotted with error bars to allow the reader to identify suitable mimics. The X-ray linear attenuation coefficients of the tested material samples spanned a wide range of values, with a small number of them overlapping established human tissue mimic values. Twenty 3D printer materials and one castable polyurethane tracked nylon and polymethyl methacrylate (PMMA) as established X-ray mimics for fat. Five 3D printer materials tracked water as an established X- ray mimic for muscle.