The Usefulness of the Air Hole Phantom for Evaluating Z-resolution and Geometric Distortion in Digital Breast Tomosynthesis

Currently, the quality control of digital breast tomosynthesis (DBT) functionality in breast X-ray equipment is not adequately implemented. In particular, DBT involves reconstruction, so depth resolution and distortion need to be evaluated. In this study, we fabricated the air hole phantoms based on the Digital Breast Tomosynthesis Quality Control Manual Ver. 1.0 (hereinafter referred to as the DBT quality control manual) and examined their usefulness as phantoms for measuring Z-resolution and geometric distortion. Using the prototype phantoms, we measured Z-resolution and geometric distortion according to the DBT quality control manual. The results of the aluminum sphere phantoms and the air hole phantoms confirmed that the z-FWHM was within or below the reference value range in the technical evaluation report by the National Coordinating Centre for the Physics of Mammography. The geometric distortion was within the specified range in the DBT quality control manual (within percentage scaling error ±5%). Therefore, it was suggested that the air-hole phantom we developed is useful for measuring the Z-resolution and geometric distortion of DBT.