  Quantum electrodynamics (qed) is used to derive the differential cross
sections measured in the three new experimental internal source ensemble x-ray
holographies: bremsstrahlung (BXH), fluorescence (XFH), and multiple-energy
(MEXH) x-ray holography. The polarization dependence of the BXH cross section
is also obtained. For BXH, we study analytically and numerically the possible
effects of the virtual photons and electrons which enter qed calculations in
summing over the intermediate states. For the low photon and electron energies
used in the current experiments, we show that the virtual intermediate states
produce only very small effects. This is because the uncertainty principle
limits the distance that the virtual particles can propagate to be much shorter
than the separation between the regions of high electron density in the
adjacent atoms. We also find that using the asymptotic form of the scattering
wave function causes about a 5-10% error for near forward scattering.
