Finite element-based biomechanical modeling of the bladder for image guided radiotherapy

Abstract

A realistic biomechanical bladder model is constructed that gives insight into pelvic organ motion as a result of bladder filling changes. We use finite element (FE) modeling to simulate bladder wall deformation caused by urine inflow. First, all pelvic structures were defined from MRI including bladder wall, small bowel, prostate, rectum, pelvic bone and the rest of the body. These were translated to FE meshes. Using appropriate material properties for all organs, displacements of these organs as a response to changing bladder pressure were computed. After fitting only the volume, the computed bladder shape has a good agreement with real bladder shape (overlap from 0.84 to 0.92). In conclusion, a FE bladder model can successfully predict the bladder shape change given a known bladder volume change. This model can potentially be used to improve image-guided radiotherapy for bladder cancer patients. © 2009 Springer-Verlag.