Suitable materials for the creation of neurosurgical phantoms using the example of a 3D printed simulation model of the posterior fossa

Background In the preceding 15 years, the implementation of 3D printing has undergone a steady increase across a variety of disciplines. In the medical domain, its use has become particularly prominent, for instance in the development of anatomical phantoms to visualize pathological conditions or to evaluate new surgical procedures. In order to identify a material that specifically mimics cranial bone, a literature review of existing skull phantoms was conducted. This was followed by a pilot study using a custom-developed phantom of the posterior fossa for the evaluation of a suitable material. Methods A literature search was conducted using the PubMed database for existing 3D printed skull phantoms. The search terms "3D printed," "skull phantom," and "neurosurgery," among others, were utilized. A total of 1,741 publications were identified in the initial review. The initial pool of articles was then narrowed down based on several inclusion criteria, including language. For the experimental study on the phantom, test blocks made from various materials were produced and subjected to craniotomy procedures. The materials were evaluated by an experienced neurosurgeon based on their drilling characteristics. The highest-rated material (White V4 resin by Formlabs) was selected for the fabrication of the final skull phantom. Results A total of 68 articles satisfied the inclusion criteria and were thus included in the analysis. The results indicated that approximately half of all phantoms, irrespective of their intended application, were fabricated using PLA. Subsequent to this, ABS and various resins from Formlabs were introduced. For the material evaluation study, nine neurosurgeons were tasked with performing a craniotomy on the phantom and assessing the material in comparison to real bone. The material (White V4 by Formlabs) was evaluated using a self-selected Likert scale, resulting in an average rating of 7.2 out of 10 points. This rating indicates that the material is deemed suitable. Conclusion The findings demonstrate that the materials used for the fabrication of skull phantoms vary significantly depending on multiple factors. However, the material testing conducted in this study led to the identification of a resin that offers favorable properties both in terms of manufacturing feasibility and cost-efficiency. This material can effectively serve as a bone substitute for neurosurgical training purposes. The results of this study may serve as a foundation for the future development of skull models, particularly in contexts where drilling characteristics similar to those of real bone are desired.