X-ray tube focal spot size, the size of the chopper wheel, and the distance to the object
being interrogated. The backscatter detectors are designed to be large enough to collect
the needed backscatter flux, and play no role in the image resolution. Depending upon
the application, a transmission detector, also shown below, may be added, if access to the
opposite side of the object under inspection is available. In this case, two images can be
displayed: the transmission image and the Compton backscatter image.