[Proton irradiation synchronized with respiratory cycle].

A sensitive strain gauge was used to detect the movement of the chest wall in order to synchronize an irradiation control system with the respiratory cycle. The output timing signal from the system is transferred to the proton accelerator for synchronized irradiation. The timing signal is set during the expiratory phase at a duration of 1.5 to 2 seconds. The efficacy of this method was evaluated by dose volume histogram based on the treatment planning program with CT images. The volume spared by this novel method was calculated in several cases, and results suggest that the method was highly effective.