Direct photon nuclear modification factor $R_\mathrm{AA}$ in Pb-Pb collisions at $\snn$=2.76 TeV for the 0-20% centrality class. As a measured direct photon spectrum is not available at $\snn$=2.76 TeV, the pQCD calculation by the McGill group was taken as pp reference. The gray band indicates the error of the $\textit{JETPHOX}$ calculation with similar PDF and FF