A study on real-time stress calculation of soft tissues using digital image techniques

With the extension of life span and advances in medical technology, there has been an increasing number of operations and procedures for human organs that were previously impossible. Successful completion of complex surgery requires considerable trial and error and medical training, which is costly and risky. To deliver a realistic feeling in virtual surgery, it is essential to know the distribution of the stresses to produce the repulsive force associated with the deformation of the organ. However, it is not possible to measure or calculate in real-time stresses of the necessary parts while observing the actual organ movements during the operation. We propose a method called the cell element method, which calculates the real-time stress by applying an external load to a soft tissue specimen. A combination of an image-processing technique along with a camera and the cell element method based on finite element method makes it possible to provide the calculated stresses as the loadings apply. For the verification of the method, we used the method of calculating the stress by measuring the strain by applying the load using the specimen made of PVC. The results are relatively close to those of finite element simulations under the same mechanical conditions.