Liver surface deformation model for minimally invasive surgery

The enormous number of advantages of minimally invasive surgery leads to the development of computer systems that are helpful tools during laparoscopic operations. In the paper a liver deformation model has been proposed including the shape deflection of the liver surface while inserting a tool into the organ and extracting it. The model is an answer to the need of better visualization during endoscopic surgery. The desired solution to this issue should be both fast and accurate. The existing solutions to the problem of internal organ deformation were briefly presented. The proposed model is an extension of previously introduced liver deflection models which have been enriched by calculating the shape of liver surface after breaking the organ structure. The main assumptions of the model have been specified. Essential mathematical transformations have been discussed. The correctness of the new model has been verified using US images of a liver while pushing and pulling a laparoscopic tool inside the organ. Pictures included in the paper enable the visual comparison of the real deformation with the one calculated using the new model.