How does ct scan pitch works?

The new CT scanners move the patient while the picture is being made. The pitch is a ratio of the speed of movement to the rotation of the machine around the patient. (the rotation of the machine is inside the cover and only seen thru the small openings). A higher pitch gives a faster scan but the images may be less detailed. A lower pitch gives a more detailed image but takes longer to acquire. This is all figured by the technologist to acquire the best image for the test being performed.