-Consider increasing the focal length ratio to two leaving the
-field of view ratio as 1, as in Figure 4. Now the detectors array is
-denser, and the real field of view is closer to that specified, but note
-again that the field of view is not used. Instead, the focal length is
-used to give a distance from the center of the phantom to the source, and
-the detector array is adjusted to give an angular coverage to include the
-whole phantom.
-