  The dominant contribution of the next-to-leading order perturbative QCD
corrections to the Upsilon -> X gamma photon energy spectrum for photon
energies w ~ m_b alpha_s can be obtained trivially from the knowledge of the
corresponding O(alpha) correction to the positronium decay spectrum in the same
region. The latter can be obtained from the NRQED computation of the
orthopositronium photon spectrum, or by applying the threshold expansion to the
1-loop QED amplitude, as it is explained in this talk.
