Gray Value Variation in Chest Imaging: Effects of Fabric Materials in Computed Radiography

Abstract

Introduction: It is generally accepted that patients undergoing chest X-rays may wear their own tops if the clothing is free from metal and is plain. However, there are concerns that such clothing could introduce artifacts, potentially impacting image interpretation. Consequently, it is common practice to require patients to change into provided garments. This study aims to assess the impact of different fabric types on grey-level values in chest radiographs. Methods: A phantom was positioned against an erect bucky in the posteroanterior position and exposed to X-rays under four conditions: a control setup without any fabric, and three experimental setups involving a radiography examination gown, a cotton t-shirt, and a polyester t-shirt. For each condition, exposure factors were set at 3 mAs and 105 kVp, with three repetitions per condition. The grey values in the processed radiographs were then calculated at seven anatomical points. Results: The radiographic examination gown consistently showed lower mean grey values at Points 4, 5, 6, and 7, indicating a reduction in mean grey value compared to the control. . These reductions were statistically significant, with the most pronounced change observed at Point 7 (Point 4 = 0.47%, p = 0.010; Point 5 = 1.92%, p = 0.017; Point 6 = 0.5%, p = 0.021; Point 7 = 4.28%, p = 0.018). Conclusion: Hospital gowns can reduce the mean grey values in certain chest areas on radiographs, potentially affecting image interpretation.