Patent ID: 8180130

Claim:
A method of determining a radial distance (R), an angular position (φ), and an axial position (Z) of a marker identified in a sequence of projection images, the method executed by an imaging system including a scanner, a computer with an electronic processing unit, and a memory module storing a marker three-dimensional localization module executable by the electronic processing unit, the method comprising: obtaining, at the computer, a sequence of images based on image data generated by the scanner, each image in the sequence of images representing an angle of rotation by the scanner and including a marker point position with a first value in a first dimension tangential to a circle of rotation of the scanner and a second value in a second dimension parallel to an axis of rotation of the scanner; analyzing, with the electronic processing unit, a behavior of the first values of the marker point positions through the sequence of images to determine the radial distance of the marker and the angular position of the marker, wherein analyzing the behavior of the first values of the marker point positions includes: (a1) selecting a sub-sampled first set of radial distance and angular position value pairs, (b1) selecting a radial distance and angular position value pair from the sub-sampled first set, (c1) determining a first range of values for each image in the sequence of images based on the selected radial distance and angular position value, (d1) determining a fitting metric for the marker point position in each image in the sequence of images if the first value of the marker point position is within the first range of values for the image, (e1) summing the metric fittings to create a cumulative fitting metric and assigning the cumulative fitting metric to the selected radial distance and angular position value pair, (f1) repeating steps (b1) through (e1) for each radial distance and angular position value pair in the sub-sampled first set, (g1) evaluating the cumulative fitting metrics assigned to each radial distance and angular position value pair in the sub-sampled first set as a function of the radial distance and angular position value pairs in the sub-sampled first set, (h1) detecting a peak of the evaluated function, the peak corresponding to a peak radial distance value and a peak angular position value, and (i1) assigning the peak radial distance value to the radial distance of the marker and assigning the peak angular position value to the angular position of the marker; and analyzing, with the electronic processing unit, a behavior of the second values of the marker point positions through the sequence of images to determine the axial position of the marker.