How many gray levels are displayed on a standard CT monitor?

The correct choice of 256 gray levels reflects the capability of standard computed tomography (CT) monitors to represent varying levels of intensity in the images produced. Each gray level corresponds to a specific intensity of X-rays that are converted into an image by the detector system.

In the context of CT imaging, a standard monitor utilizes a bit depth of 8 bits per pixel, which allows for 2 to the power of 8 different intensity values—resulting in 256 distinct levels of gray. This range ensures that the monitor can effectively display the subtle differences in tissue densities, aiding radiologists and clinicians in identifying structures or abnormalities within the scanned anatomy.

Having a selection of 256 gray levels provides a balance between image quality and system performance, which is crucial for making accurate diagnoses. Higher levels of gray, such as 512 or 1024, could enhance image detail but would require more processing power and better display technology, which may not be applicable for standard CT monitors.