In radiotherapy, it is essential to focus the radiation on the affected parts of the internal organs, like lung, liveretc., while minimizing the exposure to healthy tissues. Although methods that apply the beam to affected parts in synchronization with the patients' breathing have been used extensively, irradiation accuracy is not sufficient when the respiratory status of the patient is unstable. In this paper, we propose a new irradiation system that features (1) stabilizing the patients' respiration by synchronizing the rhythm of his/her breathing with that of music being played, and (2) controlling the timing of the irradiation based on the predicted respiratory phase instead of the measured phase that has been used widely. From experimental results using 12 subjects, it is possible to clarify that deviation of the beam irradiation position from the targeted point has been decreased to one-third as compared to conventionalmethods, resulting in a dramatic improvement in the accuracy of the irradiation system.
