Using this formula that calculates a treatment period on the basis of the irradiation start day of the week, the treatment effects depending on these start days can be compared (Table 1). If the irradiation start day of the week is determined as day 0, starting irradiation on Monday is the most effective and starting irradiation on Friday is the least effective (the survival rate increases) (Fig. 16A). For example, consider that Monday is the day of first medical examination. When worrying about whether irradiation should be started on Friday of that week or whether irradiation should be started on the following Monday, many radiation oncologists tend to consider that it is better to start on the following Monday. However, because cancer cell multiplication occurs from the time of the first medical examination to the start of irradiation, when the survival rate is compared using the GLQ model, it is more effective to start early, if possible, rather than straddling over a weekend (Fig. 16B). Here the growth rate was assumed to be only 1%.
Regarding other applications, the GLQ model can quantitatively assume the radiation effect when a split period arises.
The GLQ model shown above is the method with which the time-dose-effect relationship for external beam irradiation can be evaluated along with a time axis. Furthermore, if the value of the constant parameter can be obtained from a large amount of clinical data, a GLQ model with higher precision should be possible.