Relative biological effectiveness (RBE) for the inactivation of V79 cells were determined using the initial slopes of survival curves (published in literature), the physical quality parameters are interpolated utilizing the standard values relevant to charged particles such as protons and heliums. The issues of utilizing physical parameters as quantifier of radiation effects that influence the effectiveness have been investigated. The results show that the effectiveness may represent in terms of other physical parameters rather than linear energy transfer (LET). Meanwhile, mean free path for linear primary ionization (λ) is expressed the generalized specifier physical quality parameter to quantify ionizing radiation effects at lower doses. Therefore, plot of mean free path as a function of RBE has been made to identify the physical features of this parameter as an alternative physical quality for LET.