A method for calibrating an alignment device includes obtaining one or more projection images of a phantom having one or more surface indicators, the one or more surface indicators indicating a first coordinate system relating to the phantom, an origin of the first coordinate system overlapping with a calibration point of the phantom. The method further includes determining a difference between the first coordinate system and a second coordinate system based on the one or more projection images, the second coordinate system being relating to a medical system. The method further includes adjusting the phantom to an updated state according to the difference between the first coordinate system and the second coordinate system such that the first coordinate system overlaps with the second coordinate system. The method also includes adjusting an alignment device according to the one or more surface indicators in the updated state.
