Biomedical subjects
Publications and source records attributed to A Bzostek.
Use of active, optical tracking Surgical Guidance systems provides line of sight problems to the surgeon. We plan to use a new magnetic system, 'Aurora' from Northern Digital Inc. (Canada) and Mednetix AG (Switzerland), in intra-operative fluoroscopy to develop an integrated system for surgical guidance. Here we outline the modules developed for use with this system, including a novel registration method.
We describe a new method to cut a precise, high-quality femoral cavity in Revision Total Hip Replacement surgery (RTHR) using a surgical robot and an intra-operative C-arm fluoroscope. With respect to previous approaches, our method contains several new features. (1) We describe a novel checkerboard plate designed to correct the geometric distortion within fluoroscopic images. Unlike previous distortion correction devices, the plate does not completely obscure any part of the image, and the distortion correction algorithm works well even when there are some overlaid objects in the field of view. (2) Also included are a novel corkscrew fiducial object designed to be integrated with the robot end-effector, and a 6D pose estimation algorithm based on the two-dimensional (2D) projection of the corkscrew, used in robot-imager registration and imager co-registration. (3) In addition, we develop a cavity location algorithm, which utilizes image subtraction and 2D anatomy contour registration techniques. (4) Finally, we propose a progressive cut refinement strategy, which progressively improves the robot registration during the procedure. We have conducted several experiments, in both simulated and in vitro environments. The results indicate that our strategy is a promising method for precise orthopedic procedures like total hip replacement.
This paper describes an ongoing project to develop a computer-integrated system to assist surgeons in revision total hip replacement (RTHR) surgery. In RTHR surgery, a failing orthopedic hip implant, typically cemented, is replaced with a new one by removing the old implant, removing the cement and fitting a new implant into an enlarged canal broached in the femur. RTHR surgery is a difficult procedure fraught with technical challenges and a high incidence of complications. The goals of the computer-based system are the significant reduction of cement removal labor and time, the elimination of cortical wall penetration and femur fracture, the improved positioning and fit of the new implant resulting from precise, high-quality canal milling and the reduction of bone sacrificed to fit the new implant. Our starting points are the ROBODOC system for primary hip replacement surgery and the manual RTHR surgical protocol. We first discuss the main difficulties of computer-integrated RTHR surgery and identify key issues and possible solutions. We then describe possible system architectures and protocols for preoperative planning and intraoperative execution. We present a summary of methods and preliminary results in CT image metal artifact removal, interactive cement cut-volume definition and cement machining, anatomy-based registration using fluoroscopic X-ray images and clinical trials using an extended RTHR version of ROBODOC. We conclude with a summary of lessons learned and a discussion of current and future work.
PURPOSE: Percutaneous renal access can be challenging, particularly when the collecting system is not distended. Precise entry into a selected calyx facilitates subsequent percutaneous manipulations, but this skill requires extensive experience. In an attempt to improve accuracy while decreasing technical challenges, we developed a robotic system that automates the task of fluoroscopic image-guided percutaneous needle placement. MATERIALS AND METHODS: The prototype system consisted of a three degree-of-freedom robot with a needle injector end-effector. Imaging was provided by a biplanar fluoroscope. After correction of image distortion and fluoroscope calibration, robot to image-space registration was completed. To validate the system's ability to insert a needle into a calyx, ex vivo porcine kidneys suspended in agarose gel and distended with iodinated contrast solution were used as a model. In situ renal access tests with three 20 kg. pigs were performed. Access was confirmed by passing a flexible wire or aspirating iodinated contrast from the collecting system. RESULTS: The diameter of target calyces ranged from 3 to 7 mm. The in vitro accuracy of final needle tip positioning was 0.43 mm. In the ex vivo model, successful "one stick" access occurred on 10 of 12 attempts (83%). In situ access on the first attempt was successful for 6 of 12 target calyces (50%). Needle or tissue deflection accounted for each failure. CONCLUSION: The feasibility of a robotic system to assist in the percutaneous access of small and delicate renal calyces has been demonstrated. Additional work in reducing procedural steps and correcting for tissue deflection during needle passage is necessary to improve accuracy and to allow for clinical application.