Patent ID: 7480363

Claim:
A method for generating a wall thickness map of an object by converting digital data representing a digital radiographic image into a display map representing the absolute thickness of the object, said method comprising the steps of: a. providing an X-ray or gamma ray radiation source for directing radiation through a region of said object; b. providing a radiation detector having a plurality of sensing elements for detecting said radiation; c. acquiring a flat field image to equalize a response from each said sensing element; d. recording numerical data indicative of an intensity of said radiation incident on each said sensing element; e. correlating said numerical data to a measurement of the thickness of said object; f. calibrating said numerical data, comprising the steps of: i. correcting for variations in a source-detector-distance (SDD) between said source and said detector by correcting the flux of X-rays or gamma rays to account for scattering; ii. correcting for variations in a source-object-distance (SOD) between said source and said object by correcting the flux of X-rays or gamma rays to account for scattering; iii. correcting for variations in a spatial frequency response (MTF) of said detector to determine the spatial extent and penetration depth of features within the object; and iv. correcting for variations in a geometric profile defining said object; and g. generating an absolute thickness map for a region of said object from said calibrated data.