Computational fluid dynamics study of lower urinary tract system based on medical imaging technology

• Main Authors: Cheng-Hsiu Yang, 楊承修
• Other Authors: Chao-An Lin
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/29500747995388492215

碩士 === 國立清華大學 === 動力機械工程學系 === 91 === In the present study, the aim is to develop a non-invasive measurement technique to diagnose patients having Bladder Outlet Obstruction (BOO). This is achieved by identifying major causes of the pressure loss in the lower urinary system by CFD methods. The CT-scan images are obtained from the Taipei Veterans General Hospital. A sequence of semi-automatic methods proposed by Ching and his co-worker is used to construct rectangular meshes from CT images. Based on the reconstructed 3-D model, CFD analysis is used to determine the detailed flow and pressure distributions within the lower urinary tract system, and it is found that the major causes of the pressure loss exists in the membranous urethra, which is obstructed zone. In the obstructed cases, there are two major losses. One is the major or frictional loss, and the other is the minor loss. Minor loss happens due to the change of geometry. The ratio of the maximum velocity in the prostate urethra to the minimum velocity in the membranous urethra is about 4. This parameter might be a good indication regarding the obstructed condition of the patients. Further studies with different obstructed conditions can be used to examine the influence of this parameter. However, the predicted pressure losses are much lower than that obtained by the field measurements. Part of the reason is that the simulation does not include the bladder, which may also cause excessive pressure loss. Another cause might be the influence of the elastic boundary, which is not accounted in the study.