  Fully relativistic treatment of the electron-atom and positron-atom
bremsstrahlung is reported. The calculation is based on the partial-wave
expansion of the Dirac scattering states in an external atomic field. A
comparison of the electron and positron bremsstrahlung is presented for the
single and double differential cross sections and the Stokes parameters of the
emitted photon. It is demonstrated that the electron-positron symmetry of the
bremsstrahlung spectra, which is nearly exact in the nonrelativistic regime, is
to a large extent removed by the relativistic effects.
