What do window level and window width control in CT imaging?

In computed tomography (CT) imaging, window level and window width are crucial parameters used to manipulate the display characteristics of the resultant images. The window level is essentially the midpoint of the range of attenuation values displayed in the image; it determines the brightness or overall density of the image. By adjusting the window level, the technologist can enhance the visibility of different anatomical structures based on their varying densities.

On the other hand, window width defines the range of attenuation values that will be displayed. A narrow window width will enhance contrast by displaying a smaller range of values, making it easier to differentiate between subtle differences in tissue density. Conversely, a wider window width will display a broader range of values, leading to a lower overall contrast in the image but allowing for greater visualization of a larger variety of structures.

Together, these adjustments allow radiologists and technologists to optimize CT images for specific diagnostic needs, emphasizing either detail in less dense tissues or overall density. This manipulation is vital for accurate interpretation of CT scans, enabling effective diagnosis and assessment of various conditions.