Self-Operating Geometry Calibration for Cone-Beam Computed Tomography Using Brute-Force Search

oAccurate scan geometry is essential for high-quality three-dimensional (3D) reconstruction in cone-beam computed tomography (CBCT). This study presents a practical and self-operating geometric calibration method that does not require dedicated calibration phantoms. It estimates three critical scan parameters—vertical shift (δv), horizontal shift (δu), and in-plane rotation angle (ϕ)—through a multi-stage brute-force search guided by mean structural similarity (MSSIM). Unlike conventional methods that rely on specially designed reference objects, the proposed approach operates solely on projection data of the object being scanned, ensuring greater flexibility and ease of use. The method was validated through simulations using a 3D Shepp-Logan phantom and experimental tests with an industrial micro-CT system and a cigarette lighter phantom. It effectively corrected geometric misalignments, enhancing image quality and reducing artifacts such as edge blurring and double contours. In conclusion, the proposed method enables accurate 3D reconstruction without requiring additional calibration setups, providing a reliable and convenient solution for practical CBCT imaging applications.