What influences the brightness of an image display on a viewing monitor?

The brightness of an image displayed on a viewing monitor is primarily influenced by the window level. In radiological imaging, the window level determines the midpoint of the range of densities displayed, effectively setting the brightness for the image. By adjusting the window level, the radiologist or technician can enhance the visibility of specific anatomical structures or tissues by increasing or decreasing the overall brightness of the image.

Window width, while it affects the contrast of an image by determining the range of gray levels displayed, does not directly control brightness. Signal intensity relates to the raw data captured during imaging but does not singularly decide how bright the display appears. Proton density is relevant in certain imaging modalities, particularly MRI, but does not play a role in adjusting the brightness of the displayed image on a monitor. Thus, focusing on the window level is key for managing image brightness effectively during interpretation.