  Loop-tree duality (LTD) allows to express virtual contributions in terms of
phase-space integrals, thus leading to a direct mapping with real radiation
terms. We review the basis of the method and describe its application to
regularize Feynman integrals. Performing an integrand-level combination of real
and virtual terms, we show how to recover physical results by simply taking the
four-dimensional limit of $d$-dimensional expressions. Moreover, this method
provides a natural physical interpretation of infrared singularities, their
origin and the way that they cancel in the complete computation.
