Research On Flexible Needle Motion Planning And Respiratory Motion Compensation Methods For Robot-assisted Urinary Puncture Surgery

Urinary cancers such as kidney cancer and prostate cancer have become an important class of diseases that affect the health of our residents.As a minimally invasive treatment method,robot-assisted puncture plays an important role in the treatment of urinary cancers.In robot-assisted puncture surgery,the use of oblique-tip flexible needle can avoid obstacles such as blood vessels and nerves,and at the same time solve the problem of indefinite deformation of the needle body and tissue,so it has attracted much attention.Motion planning and precise manipulation of flexible needle are the key to realizing accurate puncture surgery.However,due to the nonholonomic constraints of flexible needles and the presence of obstacles,at the same time,the influence of patient’s breathing and other physiological movements during ultrasound-guided puncture surgery,it is extremely difficult to realize the accurate motion plan and control of flexible needles.Research on flexible needle motion planning and respiratory motion compensation methods from the two perspectives of preoperative and intraoperative operations will provide effective support technology for precise manipulation of flexible needles,which is of great value for achieving accurate needle puncture.The algorithms based on rapid search random tree(RRT)is currently one of the mainstream algorithms in solving the problem of flexible needle motion planning.However,the large number of pseudo-feasible paths planned by them will seriously affect the calculation efficiency and stability of these algorithms.We combine reachability-guided,greedy heuristic strategies and central angle control method to develop an improved algorithm to avoid the appearance of pseudo-feasible paths.In addition,we also adopt environment adaptive sampling strategy to improve the computational efficiency and stability of the algorithm.Simulations and experiments show that our algorithm can perform more stable and faster motion planning compared with the existing RRT-based algorithms.In response to the patient’s respiratory movement during the surgery,we have designed a respiratory motion detection and compensation algorithm based on the combination of key points,block matching,point cloud registration and grouping strategies.Point sets registration is used to detect the respiratory motion of urinary organs,and then the spatial transformation is used to compensate for the respiratory motion.The test on 4D ultrasound data of Beagle dog kidney shows that the proposed algorithm achieves the single frame compensation time of no more than 0.8 seconds and compensation error of no more than 0.5 mm in terms of compensation effect.The above results verify the effectiveness of the algorithm in respiratory motion compensation.Based on the above algorithms,we have developed flexible needle motion planning and respiratory motion compensation modules on the 3DSlicer platform.Using the 3DSlicer’s supports for image,model,fiducial point,and coordinate system transformation,a flexible needle motion planning module has been developed.At the same time,based on the high-dimensional image support plug-in,the development of respiratory motion compensation module is done.