Minimally Invasive Surgery Using Heterogeneous and Asynchronous Sensors-Part I: Offline Sensors Calibration

Abstract

Minimally invasive surgery (MIS) is not currently widely used by surgeons due to its cost, and complex training requirement of   the existing technology. As a first step toward making MIS a more accessible technology to use is to provide the surgeon with quality images inside the patient as well as the surgical tool location automatically in real time in a common reference frame.  The objective of this paper is to build a platform to accomplish this goal. A set of three heterogeneous asynchronous sensors is proposed to help the surgeon navigate surgical tools inside the human body. The proposed system consists of a Laser Range Scanner(LRS) to emulate the pre-op CT/MRI, an Electromagnetic Tracking System(EMTS), and a small size Camera.  This set of sensors provides all the necessary information needed for MIS navigation. The sensors have different data rate, reference frames, and independent clocks. A prerequisite for successful navigation   is to represent all the sensors data in a common reference frame.  The focus of this paper is on off line calibration of the three sensors, i.e. before the surgical device is inserted in the human body.  This is a prerequisite for real time navigation inside the human body. The proposed off line calibration technique was tested using experimental laboratory data. The result of calibration was promising with an average error of 0.1081mm and 0.0872mm along the x and y directions, respectively, in the 2D camera image.