The

We review the first complete calculation performed within the Four Dimensional Regularization scheme (FDR), the recently-proposed approach for addressing multi-loop calculations, which is simultaneously free of infinities and gauge-invariant in 4 dimensions. As a case study, the 1-loop-induced amplitude for the Higgs boson decay into two photons was calculated in arbitrary gauge. The result obtained, identical to that assessed with standard methods, stands as an explicit test of the gauge-invariance property of FDR. Moreover, the calculation provides an insight into the use of the technique, in particular in the presence of fermions