A system includes a storage device storing a set of instructions and at least one processor in communication with the storage device, wherein when executing the instructions, the at least one processor is configured to cause the system to determine a first scan area on a scanning object. The system may also acquire raw data generated by scanning the first scan area on the scanning object and generate a positioning image based on the raw data. The system may also generate a pixel value distribution curve based on the positioning image, and determine a second scan area on the scanning object based on the pixel value distribution curve. The system may also scan the second scan area on the scanning object.
