1. A Computed Tomography (CT) pilot image acquisition method, comprising: performing a helical scan on a predetermined area to be scanned, so as to obtain scanning data; reconstructing a tomographic image based on the scanning data; performing, at a predetermined positioning angle, a parallel beam projection on the tomographic image by using a virtual parallel X-ray beam, so as to obtain projection data; and re-binning a CT pilot image at the predetermined positioning angle based on the projection data.