Direct determination of geometric alignment parameters for cone-beam scanners

Area of Science:

• Medical Imaging
• Geometric Calibration
• Cone-Beam Tomography

Background:

• Accurate geometric calibration is crucial for quantitative imaging in cone-beam CT and SPECT.
• Existing methods may have limitations regarding scanner geometry and detector orientation.
• Robust calibration is essential for reliable image reconstruction and analysis.

Purpose of the Study:

• To present a comprehensive method for determining geometric alignment parameters of cone-beam scanners.
• To develop a calibration technique applicable to various scanner configurations, including X-ray and SPECT systems.
• To validate the method's accuracy and robustness through simulations.

Main Methods:

• Utilizes a specifically designed calibration phantom with point-like objects.
• Determines nine geometric parameters per view by analyzing projected marker positions on the detector.
• Employs direct formulae, treating each view independently without restrictions on scanner geometry.

Main Results:

• The proposed method provides unique solutions for diverse scanner geometries, even with partial data loss.
• A simpler phantom is suitable for common near-planar trajectories.
• Numerical simulations demonstrate the method's accuracy and robustness in parameter estimation and image reconstruction.

Conclusions:

• The developed geometric calibration method is comprehensive and versatile for cone-beam scanners.
• The technique offers accurate parameter determination and robust performance validated by simulations.
• This approach enhances the reliability of quantitative imaging in cone-beam systems.