The present disclosure is related to systems and methods for calibrating a radiation device. The method includes obtaining a plurality of images acquired at each of at least one source-to-image distance (SID) by the imaging device. The method includes determining, based on the plurality of images, at least one first projection position of a first axis of the collimator on the imaging device and at least one second projection position of a second axis of the radiation beam on the imaging device. The method includes determining, based on the at least one first projection position and the at least one second projection position, at least one offset distance between the first projection position and the second projection position. The method includes determining whether to calibrate the radiation device by comparing the at least one offset distance with a threshold.
