Registration of three dimensional image data with patient in a projection imaging system

A method for registration of a previously acquired three-dimensional image data set of an organ of interest in a patient, to the patient positioned in a projection imaging system, comprising the steps of:

• (a) identifying an initial three-dimensional center point estimate for the three-dimensional organ of interest from projections acquired in the projection imaging system;
• (b) identifying at least two extreme landmark points on a set of at least one projection acquired in the projection imaging system and defining a set of landmark-associated projections;
• (c) defining a plurality of cross-section planes with respect to the three-dimensional data, and automatically obtaining by segmentation of the three-dimensional image data a set of contour points for a plurality of lines on each of the plurality of cross-section planes;
• (d) defining a plurality of three-dimensional grid points for an initial set of grid parameters, and centering the three-dimensional grid on the initial estimate of the organ center obtained in step (a);
• (e) centering the three-dimensional image data set on a point of the grid defined in step (d) and for each of the projection in the projection set of step (b), performing a projection of every contour point in a first subset of the cross-section plane set obtained in step (c), and selecting from the cross-section plane subset the extreme cross-section plane with the contour point projecting nearest to the user-identified landmark point of step (b), and retaining the distance from the projection of that extreme contour point to the identified landmark projection point as an additive component to a figure-of-merit;
• (f) defining a refined set of sampling parameters for the cross-section plane set of step (c), and an associated second subset of cross-section planes in the neighborhood of the extreme plane identified in step (e), and iterating over step (e);
• (g) calculating the figure-of-merit as the sum over the projection set of step (b) of the additive figure-of-merit components of step (f);
• (h) iterating steps (e) to (g) for each grid point of the grid defined in step (d) in turn by placing the center of the three-dimensional image set on the grid point, and selecting as the new three-dimensional organ center estimate the grid point that minimizes the figure-of-merit;
• and
• (i) iterating step (h) over a series of three-dimensional grids replacing the grid of step (d) and defining successively finer samplings of the three-dimensional volume in a neighborhood of the three-dimensional organ center estimate obtained in step (h), and obtaining a final three-dimensional organ center estimate from which to calculate a translation vector,
• whereby registration of the previously acquired three-dimensional data set of an organ of interest to the patient positioned in the projection imaging system is achieved with a degree of efficiency by applying the translation vector of step (i) to the three-dimensional data set.