A multifunctional geometric phantom for digital radiography assessment.

Introduction: Geometric accuracy in digital radiography is essential for maintaining image quality, diagnostic reliability, and regulatory compliance. Misalignments in beam orientation can introduce distortion, affect spatial measurements, and compromise diagnostic outcomes. Despite its importance, current quality control (QC) tools rarely provide integrated assessments of all relevant geometric parameters.

Methods: A modular three-layer geometric phantom was developed to assess beam perpendicular, beam area alignment, magnification, and object displacement. Radiographic tests were conducted using varied focus-to-detector distance (FDD) (50, 60, and 70 cm). Measurements were extracted from radiographic images using image processing software, and statistical analyses were applied to evaluate the relationship between magnification and displacement.

Results: At shorter FDD, beam deviation increased, with a maximum angular deviation of 0.28° at 50 cm. Beam alignment deviation ranged from 2.00 % at 50 cm to 1.29 % at 70 cm, all within acceptable limits. Object magnification increased significantly with greater object-detector distance and smaller FDD. A strong linear correlation was found between magnification and displacement (r = 0.9987, p < 0.0001), with an estimated displacement increase of ±0.56 mm for every 0.01 magnification unit.

Conclusion: The proposed phantom effectively quantifies geometric deviations in digital radiography, producing consistent and statistically robust measurements across varied imaging conditions. These findings highlight its potential as a reliable and practical tool for quality control applications.

Implication for practice: This phantom offers a cost-effective, adaptable solution for routine QC procedures in radiographic imaging. Its ability to directly quantify geometric errors supports more precise calibration, reduces the risk of image distortion, and enhances diagnostic confidence. Adoption of this tool in clinical and regulatory settings can improve patient safety and standardize imaging performance evaluation.