Why must clinicians exercise caution when comparing exposure index values across different DR manufacturers?

• A. All manufacturers use identical scales
• B. They may use different scales, so direct comparison can be misleading
• C. They are unrelated to dose
• D. They provide the same value for the same exposure

Answer: (B)

Exposure index values are not standardized across DR systems. Each manufacturer uses its own algorithm and scale to convert detector signals into a numeric indicator, so the same actual exposure can yield different index numbers on different manufacturers’ systems. Because this index is a relative proxy influenced by detector sensitivity, processing, beam filtration, patient size, and backscatter, it doesn’t translate directly to a universal dose. That’s why direct cross-vendor comparisons can be misleading. In practice, compare exposure indices to the target values specific to the same vendor and system, or use a universal dose metric (like entrance skin dose or dose-area product) when cross-vendor comparisons are necessary.