Deep Insertion of Long Slender Needle into Deformable Tissue and the Application for Prostate Brachytherapy

This paper presents an analytical modeling and control of long slender needle insertion for medical surgery applications. Deep insertion of percutaneous needles has become widely utilized in minimal invasive surgery for medical treatments, for example, the brachytherapy treatment for prostate cancer. Long slender needles carrying the radioactive seeds are inserted into the human body and the seeds are released at the correct locations in the tumor site. The effectiveness of the treatment highly depends on the insertion accuracy of the seeds array. However, the flexibility of the needles and the deformability of the soft tissue significantly increase the difficulty of accurate insertion. Additionally, the cutting path of the needle is strictly limited by the surrounding organs, vessels, and nerve bundles. The controllability of the needle and the accuracy of the insertion remain as big challenges to both medical doctors and biomedical engineers.;This study presents a set of novel methods to analyze the insertion process and the coupling effect between the flexible needle and the soft tissue during the deep insertion. A novel stage-wise differential beam modeling of medical needle insertion processes is proposed to improve the accuracy of deep insertion. A backward compensation technique is developed to serve as a useful preplan tool for brachytherapy surgery treatments. Experiments were conducted and used for validating the developed analytical modeling.;By developing the analytical modeling and the corresponding methodologies, the research offers a tool that helps the medical doctors to analyze and choose the best design parameters of biomedical needles, in order to perform better deep insertion treatment such as tissue biopsy, drug delivery, and seed planting. The presented techniques can be used in the design and manufacturing of new generation of steerable needles for a wide range of medical applications.