  An approximate approach for the description of the two-photon bremsstrahlung
emitted by a relativistic projectile scattered in a spherically-symmetric field
is developed. It based on the accurate treatment of the analytical structure of
the singularities in relativistic one-photon free-free matrix elements. For the
case of a Coulomb field the analytical expressions for the amplitude and cross
section of process are presented. Numerical results obtained within the
framework of the proposed approach are compared with the available experimental
data and with the results of simpler theories.
