Assessment and selection of filler compounds for radiopaque PolyJet multi-material 3D printing for use in clinical settings

The aim of this research was to assess a selection of radiopaque filler compounds for increasing radiopacity in a resin suitable for Polyjet multi-material 3D printing. A radiopaque resin has potential applications in medicine to produce patient-specific anatomical models with realistic radiological properties, training aids, and skin contacting components such as surgical or procedural guides that require visibility under fluoroscopy. The desirable filler would have a high level of radiopacity under ionising imaging modalities, such as X-ray, CT, fluoroscopy or angiography. Nine potential filler compounds were selected based on atomic number and handling risk: barium sulphate, bismuth oxide, zirconium oxide, strontium oxide, strontium fluoride, strontium carbonate, iodine, niobium oxide and tantalum oxide. The fillers were evaluated using selected criteria. A weighted material selection matrix was developed to prioritise and select a filler for future 3D printing on a multi-material 3D printer. Zirconium oxide was the highest scoring filler compound in the material selection matrix, scoring 4.4 out of a maximum of 5. MED610^TM resin doped with zirconium oxide was shown to be UV curable, and when cured is non-toxic, environmentally friendly, and has the ability to display antimicrobial properties. In terms of radiopacity, a sample with thickness 1.5 mm of MED610™ resin doped with 20 wt.% zirconium oxide produced X-ray radiopacity equivalent to 3 mm of aluminium. Zirconium oxide was selected using the material selection matrix. This radiopaque resin can be used to produce anatomical models with accurate radiological properties, training aids or skin contacting devices that require visibility under ionising imaging modalities. The 3D printing validation run successfully demonstrated that the material selection matrix prioritised a filler suitable for radiopaque multi-material 3D printing.