Development of a novel robot for transperineal needle based interventions: focal therapy, brachytherapy and prostate biopsies.

PURPOSE: We report what is to our knowledge the initial experience with a new 3-dimensional ultrasound robotic system for prostate brachytherapy assistance, focal therapy and prostate biopsies. Its ability to track prostate motion intraoperatively allows it to manage motions and guide needles to predefined targets. MATERIALS AND METHODS: A robotic system was created for transrectal ultrasound guided needle implantation combined with intraoperative prostate tracking. Experiments were done on 90 targets embedded in a total of 9 mobile, deformable, synthetic prostate phantoms. Experiments involved trying to insert glass beads as close as possible to targets in multimodal anthropomorphic imaging phantoms. Results were measured by segmenting the inserted beads in computerized tomography volumes of the phantoms. RESULTS: The robot reached the chosen targets in phantoms with a median accuracy of 2.73 mm and a median prostate motion of 5.46 mm. Accuracy was better at the apex than at the base (2.28 vs 3.83 mm, p <0.001), and similar for horizontal and angled needle inclinations (2.7 vs 2.82 mm, p = 0.18). CONCLUSIONS: To our knowledge this robot for prostate focal therapy, brachytherapy and targeted prostate biopsies is the first system to use intraoperative prostate motion tracking to guide needles into the prostate. Preliminary experiments show its ability to reach targets despite prostate motion.

A realistic deformable prostate phantom for multimodal imaging and needle-insertion procedures.

PURPOSE: Phantoms are a vital step for the preliminary validation of new image-guided procedures. In this paper, the authors present a deformable prostate phantom for use with multimodal imaging (end-fire or side-fire ultrasound, CT and MRI) and more specifically for transperineal or transrectal needle-insertion procedures. It is made of soft polyvinyl chloride (PVC) plastic and includes a prostate, a perineum, a rectum, a soft periprostatic surrounding and embedded targets for image registration and needle-targeting. Its main particularity is its realistic deformability upon manipulation. METHODS: After a detailed manufacturing description, the imaging and mechanical characteristics of the phantom are described and evaluated. First, the speed of sound and stress-strain relationship of the PVC material used in the phantom are described, followed by an analysis of its storage, imaging, needle-insertion force, and deformability characteristics. RESULTS: The average speed of sound in the phantom was measured to be 1380 ± 20 m/s, while the stress-strain relationship was found to be viscoelastic and in the range of typical prostatic tissues. The mechanical and imaging characteristics of the phantom were found to remain stable at cooler storage temperatures. The phantom had clearly distinguishable morphology in all three imaging modalities, with embedded targets that could be precisely segmented, resulting in an average US-CT rigid registration error of 0.66 mm. The mobility of the phantom prostate upon needle insertion was between 2 and 4 mm, with rotations between 0° and 2°, about the US probe head. CONCLUSION: The phantom's characteristics compare favorably with in vitro and in vivo measurements found in the literature. The authors believe that this realistic phantom could be of use to researchers studying new needle-based prostate diagnosis and therapy techniques.

Evaluation of the Needle Positioning Accuracy of a Light Puncture Robot Under MRI Guidance: Results of a Clinical Trial on Healthy Volunteers.

PURPOSE: To assess the accuracy of Light Puncture Robot (LPR) as a patient-mounted robot, in positioning a sham needle under MRI guidance for abdominal percutaneous interventions. MATERIALS AND METHODS: This monocentric, prospective and non-controlled study was approved by the ethics review board. The study evaluated the accuracy of LPR V3 to achieve a virtual puncture in 20 healthy volunteers. Three trajectories were tried on each volunteer, under 3-T MRI guidance. RESULTS: Accuracy under 5 mm in attaining a 10 cm-deep target was reached in 72% of attempts after 2 robot motions with a median error of 4.1 mm [2.1; 5.1]. Median procedure time for one trajectory was 12.9 min [10.2; 18.0] and median installation time was 9.0 min [6.0; 13.0]. CONCLUSION: LPR accuracy in the deployment of a sham needle inside the MRI tunnel and its setup time are promising. Further studies need to be conducted to confirm these results before clinical trials.

Using CamiTK for rapid prototyping of interactive computer assisted medical intervention applications.

Computer Assisted Medical Intervention (CAMI hereafter) is a complex multi-disciplinary field. CAMI research requires the collaboration of experts in several fields as diverse as medicine, computer science, mathematics, instrumentation, signal processing, mechanics, modeling, automatics, optics, etc. CamiTK is a modular framework that helps researchers and clinicians to collaborate together in order to prototype CAMI applications by regrouping the knowledge and expertise from each discipline. It is an open-source, cross-platform generic and modular tool written in C++ which can handle medical images, surgical navigation, biomedicals simulations and robot control. This paper presents the Computer Assisted Medical Intervention ToolKit (CamiTK) and how it is used in various applications in our research team.

Interventional radiology robot for CT and MRI guided percutaneous interventions.

This paper introduces a new patient-mounted CT and MRI guided interventional radiology robot for percutaneous needle interventions. The 5 DOF robot uses ultrasonic motors and pneumatics to position the needle and then insert it progressively. The needle position and inclination can be registered in the images using two strategically placed fiducials visible in both imaging modalities. A first prototype is presented and described in terms of its sterilization, CT and MRI compatibility, and precision. Tests showed that 1) it is entirely sterilizable with hydrogen peroxide gas, 2) no image artifacts or deformations are noticeable in the CT and MRI images, 3) does not affect the SNR of MR images, and 4) its mechanical error is less than 5mm.

Design of an ultrasound-guided robotic brachytherapy needle-insertion system.

In this paper we describe a new robotic brachytherapy needle-insertion system that is designed to replace the template used in the manual technique. After a brief review of existing robotic systems, we describe the requirements that we based our design upon. A detailed description of the proposed system follows. Our design is capable of positioning and inclining a needle within the same workspace as the manual template. To help improve accuracy, the needle can be rotated about its axis during insertion into the prostate. The system can be mounted on existing steppers and also easily accommodates existing seed dispensers, such as the Mick Applicator.