 We developed a mathematical model that combined an ordinary differential equation, ODE, and microdosemetric kinetic model, MKM, to predict the tumor cell lethal effect of stereotactic body radiation therapy, SPRT, applied to non-small cell lung cancer, NSCLC. This model allowed us to evaluate the effects of varying the ratio of active and quiescent tumors for the total tumor volume, as well as the length of the dose delivery time per fractionated dose, TINTA, on the initial tumor volume. Our results showed that the combination of MKM and mathematical model of tumor growth, MMTG, significantly reduced the radiation effectiveness value, REV, when compared to the combination of linear quadratic model, LQM, and MMTG. Additionally, we found that the ratio of active tumors and the prolonging of TINTA affected the decrease in the REV for A549, and H460 cells. This article was authored by Hisoshi Nakano, Tokahiro Shinoki, Satoshi Tonabe, and others.