CT-directed robotic biopsy testbed: user interface and coordinate transformations

CT-guided percutaneous biopsy is a widely accepted practice in the medical field. Because efficient and safe CT-guided percutaneous interventions require accurate needle placement, there are limitations to the accuracy obtainable using free-hand techniques, particularly for small or deeply situated target areas. In addition, CT-directed percutaneous biopsy can be tedious and time consuming, since frequent re-imaging may be required. As a demonstration platform, we are developing a robotic biopsy testbed incorporating a mobile CT scanner, a small “needle driver” robot, and a localizer. This testbed will be used to compare robotically assisted biopsy to the current manual technique. The testbed will also allow us to investigate software architectures for integrating various hardware and software components. This testbed is the first step in developing the robotically assisted biopsy system of the future. In this paper, we present the overall concept and then provide details about the user interface and coordinate transformations.