To reduce patient entrance skin exposure (ESE), higher kVp exposures are considered. Which statement is true?

• A. It reduces patient dose but not affect histogram
• B. kVp values that are excessively high can negatively impact the data histogram
• C. No effect on histogram
• D. Excessively high kVp improves histogram

Answer: (B)

When you raise kVp, you increase beam penetrating power, so you can use less mAs and reduce entrance skin exposure. But higher kVp also lowers the difference in attenuation between tissues, and it increases scattered radiation. In digital radiography, the histogram reflects how the detected gray values are distributed across the image. If kVp becomes excessively high, the reduced subject contrast and more scatter blur that distribution, causing the histogram to shift or flatten in ways that can undermine accurate exposure indexing and image processing. So, while dose goes down, the data histogram can be negatively affected by very high kVp. The other ideas assume no effect or an improvement to the histogram, which isn’t consistent with how energy spectrum and scatter influence the recorded gray-level distribution.