Prostate cancer is the second highest cause of cancer related deaths among men. According to the diagnostic pathway for prostate cancer, a prostate biopsy is performed if an individual showed signs of lesions through high prostate-specific antigen (PSA) concentration or suggestive digital rectal exam (DRE) results. The core biopsy mechanism involves inserting a beveled needle into the organ and removing a cylindrical fragment of tissue. Many factors affect the histological quality of the sample, including fragmentation, needle deflection, and needle insertion velocity. If a biopsy core is not clinically viable, an alternative core will need to be taken, resulting in increased patient trauma and potential risk of infection.
Many of these relevant factors are impacted by sources of friction in the system. Prior studies have examined methods of decreasing the friction of the interactions between different components of the biopsy system to reduce the negative effects on histological sample quality. While scenarios have been explored that examine reducing the friction between the needle and tissue through sharpening and polishing techniques, the friction introduced by the needle guide in template guided core prostate biopsies has not been analyzed in the decades since its development. This study aims to introduce the biopsy guide as an additional source of friction which can be optimized to reduce friction force, while proposing and testing several configurations of the needle guide that would reduce the friction force of the system. A Finite Element Analysis (FEA) was conducted using SIMULA Abaqus modeling software, and the simulation was correlated with a derived equation that estimated friction force according to material properties.
The study demonstrated that configurations for the internal surface of the needle guide which provided decreased contact surface compared to the control needle guide resulted in lower friction force between the needle and guide. Conditions which had contact points oriented parallel to the direction of insertion had the lowest recorded friction force. This suggests that the traditional biopsy needle guide may be optimized to introduce less friction force by reducing the contact area between the needle and guide inner surface. This has application in reducing the number of passes required to obtain a histologically viable core specimen, and therefore reducing the opportunity for patients to develop infection.
Bachelor of Science (B.S.)
College of Medicine
Girgis, Isaac, "Mechanical Understanding and Optimization of Template Guided Core Needle Biopsy" (2022). Honors Undergraduate Theses. 1447.