GEOMETRIC PARAMETER DETERMINATION METHOD FOR CONE BEAM COMPUTED TOMOGRAPHY SYSTEM

摘要

The invention provides a geometric parameter determination method for a cone beam computed tomography system. The method comprises: obtaining first projection data when a CBCT system detector is in an unbiased state and second projection data when the CBCT system detector moves horizontally to a set bias state, respectively under the condition that the CBCT system detector is in an unbiased state and the CBCT system detector is horizontally moved to the set bias state (S10); obtaining a projection data set A in the first projection data, calculating a center point coordinate of the projection data set A, acquiring a projection data set B in the second projection data, and calculating a center point coordinate of the projection data set B (S20); determining estimated coordinates of a projection of a sphere center of each small ball markers in a CBCT geometric parameter correction device and an objective function of the CBCT geometric parameter correction device, according to the center point coordinates of the projection data set A, the center point coordinates of the projection data set B, and the correspondence between the projection data set A and the projection data set B (S30); and calculating the estimated coordinates when the objective function takes the minimum value to obtain an optimized estimate, and determining geometric parameters of the CBCT system during the sampling process on the basis of the optimized estimates (S40).