Up to now, there has never been a simple and easy method for immediate calculation of ion ranges in different human tissues. The current available calculations require, besides the ion energy and the target density, further target parameters like the atomic number, mass number, chemical composition in case of multi-elemental targets and the mean ionization potential. For complex biological targets, these parameters are not always reliably known and it is not feasible to obtain them from CT data. This book aims specifically at exploring possibilities of simple parameterization of ion ranges in a selected set of human tissues as modelled in SRIM (Stopping and Range of Ions in Matter). Besides that, influences of density inhomogeneities and positionally varying target layers are going to be explored. For related densities, it is feasible to express ranges of the particles as a simple power function with one input parameter - the target density. This favourable approach will be especially useful for professionals in the particle radiotherapy departments or research centres dealing with proton and carbon ions.