1：Experimental Design and Method Selection:

A prospective phantom study using an anthropomorphic chest phantom (Lungman) with and without chest plates to simulate average and larger size patients. Radiographic acquisitions were performed using routine clinical protocols from 17 X-ray machines across eight hospitals. Image quality was assessed using relative visual grading analysis (VGA) and 2 alternative forced choice (2AFC) methods by six observers. Radiation dose was measured using a solid-state dosimeter for incident air kerma (IAK).

2：Sample Selection and Data Sources:

The Lungman phantom (Kyoto Kagaku, Japan) was used, with chest plates added to simulate larger body size. Images were acquired in DICOM format from the X-ray machines.

3：List of Experimental Equipment and Materials:

Lungman chest phantom, chest plates, 17 diagnostic X-ray machines (various manufacturers and models), solid-state dosimeter (RaySafe X2), computer monitors (DOME E5) for image display, and software for data analysis (SPSS version 22.0).

4：0). Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: Quality control tests were conducted on X-ray machines based on IPEM report 91. The phantom was positioned for PA chest radiography, and images were acquired using local protocols for both standard and larger sizes. IAK was measured three times for manual exposures and estimated using a regression equation for AEC exposures. Images were evaluated by observers in controlled lighting conditions.

5：The phantom was positioned for PA chest radiography, and images were acquired using local protocols for both standard and larger sizes. IAK was measured three times for manual exposures and estimated using a regression equation for AEC exposures. Images were evaluated by observers in controlled lighting conditions. Data Analysis Methods:

5. Data Analysis Methods: Data normality was tested using Shapiro-Wilk test. Pearson's correlation was used for IAK and IQ correlation, unpaired t-test for IAK differences, Mann-Whitney test for IQ differences, and inter-class correlation coefficient (ICC) for inter-observer variability. Statistical analysis was performed with SPSS software.