Systems and methods for inspecting an object with a scanned beam of
penetrating radiation are disclosed. Scattered radiation from the beam is
detected, in either the backward or forward direction. Characteristic
values of the backscattered radiation are compared to expected reference
values to characterize the object. Additionally, penetrating radiation
transmitted through the inspected object may be combined with scatter
information. In certain embodiments, the inspected field of view is less
than 0.1 steradians, and the detector is separate from the source of
penetrating radiation and is disposed, with respect to the object, such
as to subtend greater than 0.5 steradians in the field of view of the
object.