Line-based iterative geometric calibration method for a tomosynthesis system.

Area of Science:

• Medical Imaging Physics
• Tomosynthesis System Calibration
• Image Reconstruction Algorithms

Background:

• Next-generation tomosynthesis (NGT) systems feature complex acquisition geometries (2D source/detector motion, magnification).
• Conventional position-based geometric calibration methods are insufficient for these advanced NGT systems.

Purpose of the Study:

• To develop and validate a novel line-based iterative method for accurate geometric calibration of NGT systems.
• To address the limitations of existing methods in complex NGT acquisition scenarios.

Main Methods:

• A line-based iterative approach using virtual line segments between fiducials in a calibration phantom.
• Minimizing projection error between true and estimated fiducial line segments to determine system geometry.
• Assessment via simulations and experiments across four NGT geometries (X, T, XZ, TZ), including magnification studies.

Main Results:

• The line-based iterative method demonstrated high robustness to geometric perturbations and fiducial inaccuracies (mean error < 0.02 mm).
• Accurate calibration was achieved for magnified images (1.85x) using contact-mode acquisition.
• Evidence of super-resolution and improved image quality (isotropic CTF, reduced artifacts) with advanced calibration methods.

Conclusions:

• The proposed line-based iterative calibration method is a robust and superior alternative for advanced NGT systems.
• It effectively handles complex geometries and fiducial misalignments, surpassing traditional calibration techniques.