The Design of an Anthropomorphic Brain Phantom

Abstract

Brain, outside the body, will decay quickly, causing ex vivo studies to be difficult. Having a phantom model has a great beneficial value for numerous reasons. Phantoms are, among others, used in research centres, to validate new equipment, to develop biomechanical models or to test new treatment methods. They are representations of organs or tissues made from tissues that mimicking the desired properties of the organ. This thesis research is performed in collaboration with Philips Healthcare research department. They benefit from having a brain phantom for the development of a new endoscopic tool that incorporates virtual reality images in the view. Existing phantoms are usually expensive and are not meant for destruction by needle interventions or endoscopic interventions, or are a very rough representation of reality. For this study, it was the aim to develop an anthropomorphic brain phantom containing the hollow space of the ventricles of the brain, with the correct mechanical and optical characteristics. From a digital 3D mesh brain, moulds were made to assess different ways to produce a brain phantom with ventricles. From literature, the tissue mimicking material (TMM) PVA was selected to use for the production of the phantom. After evaluation of the different approaches to fabricate a phantom, it was decided to produce the hollow spaces of the ventricles by using 3D printed soluble PVA, to be removed out of the model after casting. This was done by 3D printing a brain mould in which a 3D printed PVA ventricle could be inserted. A solution of 6% PVA as tissue mimicking material was used. After the mould and production principle of the model was finalized, the imaging part was assessed. In order for the phantom to be used in CT imaging, barium sulphate was added to the PVA solution as a contrast enhancing material. Two phantoms were made with 1% and 2% barium sulphate. Finally, to assess the shape and the quality of the ventricles in the phantom, the phantom was scanned with a CT scan at Philips Healthcare in Best, the Netherlands. The CT files were evaluated using RadiAnt and 3D slicer to assess the ventricular shape and position. 3D slicer was also used to segment the ventricle shape out of the designed models to compare with the originally developed ventricle structure. This study functions as a proof of concept for the development of a PVA brain phantom containing ventricles produced with 3D printed soluble PVA. All in all, the overall evaluation of the prototypes have shown to be promising models for the development of a brain phantom using PVA and ‘homemade’ fabrication techniques. The use of 3D printed soluble PVA is a novelty in this field of application. It makes the design easy to develop and easily adjusted to patient-specific cases as personalized models can be made.