Mobile radiography calibration for tomosynthesis using epipolar data consistency

A method for geometric calibration of a radiography apparatus, the method executed at least in part by a computer and comprising:

• a) acquiring a series of tomosynthesis projection images of patient anatomy by energizing an x-ray source of the radiography apparatus at a plurality of positions along a scan path and directing x-ray radiation toward a detector that is positionally uncoupled from the x-ray source;
• b) calculating an epipolar geometry according to the relative position of the detector to the scan path by:
• (i) identifying a direction for each of a plurality of epipolar lines that extend along an image plane that includes the detector;
• (ii) defining a region of interest ROI of the patient anatomy that is a partial portion of each projection image in the series, wherein the ROI is fully included within each acquired projection image in the series;
• and
• (iii) using two or more acquired projection images in the series, calculating a weighted line integral for each of the plurality of epipolar lines extending within the corresponding ROI and optimizing the calculated epipolar geometry according to a comparison of the derivatives obtained from the calculated line integrals for the two or more projection images;
• and
• c) reconstructing and displaying at least a portion of a tomosynthesis volume image according to the calculated epipolar geometry.

A radiography apparatus, comprising:

• an x-ray source configured to provide radiation from different positions along a scan path;
• a detector configured to acquire a series of tomosynthesis projection images of patient anatomy corresponding to the different positions of the x-ray source along the scan path;
• control circuitry programmed to calculate epipolar consistency according to the relative position of the detector to the scan path by:
• (i) estimating a direction for each of a plurality of epipolar lines that extend along an image plane that includes the detector;
• (ii) defining a region of interest ROI of the patient anatomy, wherein the ROI is a portion of each projection image and is fully included within each projection image in the series;
• (iii) using two or more projection images in the series, calculating a consistency metric that is indicative of the accuracy of epipolar line estimation for each of the plurality of estimated epipolar lines extending within the corresponding ROI;
• (iv) iteratively adjusting the epipolar line estimation and repeating step (iii) until the consistency metric indicates accuracy to within a predetermined threshold;
• and
• (v) reconstructing a tomosynthesis volume according to the calculated epipolar consistency;
• and
• a display configured to display at least a portion of the reconstructed tomosynthesis volume.