Optimizing the minimum detectable difference of chest protocol digital radiography system by V-shaped line gauge phantom and Taguchi analysis

Abstract

Background: The Minimum Detectable Difference (MDD) of Digital Radiography (DR) image systems was quantified and optimized using a self-developed V-shaped line gauge phantom and Taguchi optimization analysis. The increased clinical applications of the DR system are mainly due to its ability to provide instant and precise imaging for radiologists to diagnose. Objective: The purpose of this study was to optimize parameters for MDD values based on Taguchi's analysis and to verify a self-developed V-shaped line gauge phantom for the chest protocol of the DR system. Materials and methods: The chest protocol was exposed using the V-shaped line gauge and solid acrylic water phantom in various sizes with the DR system. Five factors were assigned in this study: (A) focal spot, (B) kVp, (C) mAs, (D) filter, and (E) phantom thickness. Since each factor could have two or three levels, eighteen groups of factor combinations were organized according to Taguchi’s algorithm. The V-shaped line gauge images were estimated. ANOVA was adopted to determine the significant factors and MDD values to evaluate the spatial resolution. Results: The optimal parameters for the highest Signal-to-Noise (S/N) ratio were as follows: (A) large focal spot, (B) 140 kVp, (C) 6.25 mAs, (D) 0.1 mmCu filter, and (E) phantom thickness of 16 cm. Conclusion: The optimal parameters in this study provided an MDD value of 0.87 mm compared to 1.66 mm for conventional parameters. The self-developed V-shaped line gauge phantom also proved to be suitable for the DR system. Furthermore, all factors affected the image quality with statistical significance following the ANOVA analysis.