A simulation method for 3-dimension needle invasive medical treatments of cancer infected liver

The medical insertion treatments on cancer infected liver seem to be very effective because of low invasion for patients. Planning for insertion procedure is difficult because the interaction between needle and soft tissue become complicated and the liver may deform largely under the influence of such gravity, cancer, position of needle and so on. It is of significant to grasp natural properties and deformations of liver during medical needle insertion. In this study, viscoelastic material properties are measured by experiments and constitutive equation is formulated based on the experimental results. Then a liver is modeled by finite elements made from the sliced MRI images. 3-Dimensional needle insertion procedures are simulated by quasi-static analysis assuming friction between the needle and soft tissue and conditions of tear-off elements. From the numerical results by the proposed simulation method, it is found that some navigation of the needle insertion is necessary to hit the cancer correctly.