VMAT-based blocking method and equipment for organ-at-risk irradiation

The invention discloses a VMAT-based blocking method and equipment for irradiation at risk organs. The blocking method comprises the following steps: inputting control point information, a target region and constraints of the risk organs; intensity graph optimization is carried out according to the fact that a plurality of control points form an intensity graph; determining an area needing irradiation limitation on the intensity graph according to the intensity threshold value, and adjusting the outline of the intensity graph; circularly inserting a sub-field at a control point by using DMPO, punishing an irradiation limiting area, and optimizing a corresponding MU; and decomposing the MU corresponding to each control point sub-field into a combination of a rack rotation speed and a dose rate. According to the method, the irradiation dose endangering organs and target regions can be well balanced, the shielded region is automatically selected according to the intensity threshold value, plan making is accelera