Acquisition method and device of CT value correction paper

The invention provides a method and device for acquiring a correcting document for correcting acquired image CT values of scanned objects in a scan, the method includes steps: (1) scanning at least three different materials in various scanning conditions; (2) testing to acquire actual tested CT values of various scanned materials in various scanning conditions so as to obtain a set of actual tested CT values; (3) establishing corresponding relationship between the obtained actual tested CT values and ideal CT values of each material in various scanning conditions, wherein the corresponding relationship is taken as the correcting document for determining ultimate CT values of the scanned object in the scanning condition.