Final answer:
The window width in CT imaging controls the mid-range of densities displayed, affecting the image contrast and the visibility of different tissues.
Step-by-step explanation:
The question "Window width in CT controls? a) Density b) Mid-range of densities c) Resolution d) Gray scale" pertains to the settings in computed tomography (CT) imaging that affect how the resulting images are displayed. The correct answer to this question is b) Mid-range of densities. The window width in CT imaging refers to the range of the Hounsfield units (densities) that are displayed on the image. A wider window will show a greater range of densities, affecting how contrast is perceived, while a narrow window will show fewer densities, enhancing the contrast between structures. Adjusting the window width and window level allows radiologists to better visualize different types of tissue by making subtle differences in tissue density more or less prominent on the CT scan.