Patient-specific ultrasound liver phantom: materials and fabrication method

Purpose : An anatomically realistic ultrasound liver phantom with tissue-specific distinct signal properties is needed for training of novices in diagnostic and interventional procedures. The main objective of this work was development and testing of a new durable liver ultrasound training phantom for use with a hybrid simulator. Methods : A liver ultrasound phantom was fabricated in four main phases: materials selection, segmentation of CT images and realization of 3D models, vessel and lesion realization, and final assembly with silicone casting. Silicone was used as basic material due to its durability and stability over time. Several additives were analyzed and mixed with the polymer to reproduce the echogenicity of three simulated soft tissue types: parenchyma, lesions, and veins. Results : Cysts and vessel trees appear anechoic in the B mode ultrasound images when realized with pure silicone. The liver parenchyma, hypoechoic, and hyperechoic lesions were realized with different concentrations of graphite and Vaseline oil to increase their relative echogenicity. These materials were successful for creation of an ultrasound liver phantom containing simulated blood vessels and lesions. Conclusion : The phantom reproduces the human liver morphology and provides vessels and lesions ultrasound images with recognizable differences in echogenicity. The speed of sound in the simulated materials is inaccurate, but the problem can be overcome via software adjustment in a hybrid simulator.