| In recent decades,medical phantoms play an important role in surgical planning and medical residents training.However,it is difficult to fabricate medical phantoms with both patient-specific anatomical features and mimicry of real tissue’s mechanical properties.Besides,most of phantoms are made of a single material,lacking tissue heterogeneity in real tissue.In order to overcome these limitations,we developed a 3D printing technique for manufacturing multi-layer medical phantoms with both anatomical details and mimicry of real tissue’s mechanical properties.Considering the wide use of needles in medical procedures,needle-phantom interaction was studied experimentally and numerically.First,we developed a multi-material 3D printing technique for manufacturing heterogeneous medical phantom.3D model was reconstructed from a patent’s computed tomography image,and then was segmented into different tissue layers.Printing materials were selected due to similar mechanical properties compared with their biological counterparts.A multi-material 3D printing system was built based on selected printing materials.Using this 3D printing system,multi-material medical phantoms with both anatomical details and mimicry of real tissue’s mechanical properties were successfully manufactured.To systematically study needle-phantom interaction,standard phantom specimens were designed and needle insertion experiment was carried out.The experimental results showed that manufacturing conditions,i.e.the infill rate,interfacial thickness and the silicone grease ratio,played effective roles in regulating the mechanical needle-phantom interaction.Then,needle insertion experiment was carried out on forearm phantom to investigate its ability of needle-tissue interaction modelling.At last,the mechanical mechanism of needle insertion was studied by numerical simulation.Constitutive relations and interaction model were determined based on uniaxial tensile tests and needle insertion experiments.The finite element model was built according to needle insertion experiments on standard phantom specimens.Then the effects of interfacial thickness,ultimate stress,and friction coefficient on the needle-phantom interaction were investigated,which could offer guidelines on medical phantom design. |
