The concepts of the linear cascade theory and its application to inhomogeneous targets (layered structures, mask windows, and deep trenches) are shortly reviewed. To calculate range and energy deposition distributions there exist two different levels of the theoretical description: (i) Using the static BCA Monte Carlo simulations or the linearized Boltzmann transport equations (LBTE) the profiles can be determined for a given inhomogeneous structure, (ii) The profiles of the incident ion in the homogeneous components of the inhomogeneous target are assumed to be known. Then, an appropriate combination of these distributions leads to the profile in the inhomogeneous target.