Final digital images do not display exposure indicators (EIs); brightness is used to assess IR exposure; why is this poor practice?

Final digital images do not display exposure indicators (EIs); brightness is used to assess IR exposure; why is this poor practice?

• A. Rescaling will not be completed accurately if EIs are unknown
• B. Histogram analysis cannot be performed without EI information
• C. Image contrast is determined based on the amount of radiation received by the IR
• D. Brightness does not reflect the amount of radiation the IR received

Answer: (D)

Brightness on the final image comes from post-processing choices (like window level/width and LUT) and can be adjusted after the image is acquired, independent of how much radiation actually hit the detector. Exposure indicators, when available, give a numerical, system-calibrated measure of IR exposure that correlates with the dose the detector received. Because brightness can be altered without changing the true exposure, using it to judge whether the IR received adequate radiation is unreliable. A well-exposed image in terms of detector dose might still look bright or dark depending on processing, and vice versa, so relying on brightness alone is a poor way to assess exposure.

Brightness on the final image comes from post-processing choices (like window level/width and LUT) and can be adjusted after the image is acquired, independent of how much radiation actually hit the detector. Exposure indicators, when available, give a numerical, system-calibrated measure of IR exposure that correlates with the dose the detector received. Because brightness can be altered without changing the true exposure, using it to judge whether the IR received adequate radiation is unreliable. A well-exposed image in terms of detector dose might still look bright or dark depending on processing, and vice versa, so relying on brightness alone is a poor way to assess exposure.