  We present $\gamma $-ray spectra for a set of Type Ia supernovae models. Our
study is based on a detailed Monte Carlo transport scheme for both spherical
and full 3-D geometries. Classical and new challenges of the $\gamma $ ray
astronomy are addressed. We find that $\gamma $-rays are very suitable to
reveal the structure of the envelope and, thus, they allow to probe properties
of the nuclear burning front and the progenitor, namely its central density and
global asphericities. The potential problems are discussed for the quantitative
comparison between theoretical and observed line fluxes during the first few
months after the explosion.
