Calibration phantom and recognition algorithm for automatic coordinate transformation in diagnostic imaging

Abstract

A phantom ( ) is positioned on a patient support couch ( ) of a diagnostic imaging scanner ( ). The phantom includes a plurality of diagnostically imageable elements ( ) which are mounted in a fixed relationship such that when projections are made along three orthogonal axes, the projections of the diagnostically elements along each axis are non-overlapping. At least three markers ( ) on the phantom are monitored by infrared sensitive cameras ( ) or other pick-up devices and the location of the markers in image guided surgery (IGS) space is determined ( ). From a priori information about the structure of the phantom, the geometric centers of the imageable elements is determined and projected ( ) along the coordinate system axes of IGS space. The phantom is imaged by the diagnostic imaging system to generate projections of the diagnostically imageable elements along each of three coordinate axes of diagnostic image space. By comparing the centers of the imageable elements in the IGS coordinate system with the locations of the centers of the imageable elements in diagnostic image space, a transform between the IGS and image space coordinate systems is determined ( ). Subsequent diagnostic images of patient are transformed ( ) with the transform from diagnostic image to image guided surgery space.