Method and device for reducing irradiation deviations caused by respiration during radiotherapy

The invention discloses a method for reducing irradiation deviations caused by respiration during radiotherapy. During the process of controlling the beam emerging time of radiation therapy device, chest motion of a patient during respiration can be tracked, and the starting and the ending times of the radiation therapy device can be controlled according to the tracks of the chest motion of the patient during respiration. The invention further provides a device for achieving the method, wherein the device comprises a radiation therapy device, a camera and a computer. A luminous reference marker is used for following the up-and-down motions of the chest of the patient during the respiration, the camera is used for collecting the motion images of the luminous reference marker in real time, the computer is used for computing the motion tracks, a beam emerging start point and a beam emerging end point of the radiation therapy device can be determined according to motion tracks, the method provided by the inventio