What will happen if the window level is increased while keeping the window width constant?

Increasing the window level while keeping the window width constant will affect the brightness of the image. The window level determines the center of the range of pixel values that will be displayed, while the window width controls the range of pixel values around that center. When you increase the window level, you effectively shift the brightness of the image upward, leading to a brighter appearance of the midtones.

In the context of computed tomography, as the window level is increased, higher pixel values (which correspond to higher density structures, such as bone) will be displayed more prominently, while lower pixel values (such as soft tissues or air) will be less visible. Therefore, the overall impression is that the image becomes brighter as more of the high-density structures are represented at higher levels of brightness.

By contrast, if the window level were decreased, it would lead to a darker image since lower pixel values would be highlighted more. This understanding of how window level and width operate is crucial for optimizing image quality in CT imaging. The choices reflecting changes in contrast or constant brightness do not pertain to the specific action of increasing the window level at a constant width.