The time, dose, and fractionation relationships of irradiation follow the generalized LQ model (GLQ model). Figure 19 shows the effect of fractionated irradiation (60Gy/30fr/6weeks) on a tumor in three-dimensional space. It was assumed that one cancer cell proliferates according to the Big Bang model and radiotherapy is started after 700 days. Similarly, 500 cancer cells were generated and fractionated irradiation of 60Gy/30fractions/6 weeks was administered. Local control was obtained when fewer than one cell remained after irradiation per clone in all clones . Tumors were defined as uncontrolled under all other conditions. To determine the overall trend, the effect was evaluated 120 days after irradiation.
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Local control is more difficult for larger tumors (Fig. 20).
Local control is more difficult as the number of clones in the tumor increases (Fig. 21).
Even if there is only one clone in the tumor, local control may be difficult (Fig. 22).
When radio-resistant clones, such as SQ20B are included, local control may be difficult even if the tumor is small (Fig. 23).