One of the technologies in use involve x-ray scanning with backscatter imaging.
Referring to Figure 1, in conventional radiography an object of interest (M) which
may include an added absorber (A) is placed between a source of x-rays S and an
imaging detector I. The detector produces a “negative” of the absorbing power of the
M-A combination. X-rays can scatter in M and A and reach the detector, degrading
image quality. A grid can be placed between M and I to reduce scatter. In backscatter
imaging, a source/collimator (S/C) assembly is scanned over the object of interest,
and a non-imaging detector (N-I) is placed between the collimator and the object. Xrays
that undergo Compton scatter in the object may reach the detector. Position
information is obtained by knowing where the x-ray beam is. Photons can undergo