Converting a digital radiograph to an absolute thickness map

A system for generating a wall thickness map of an object by converting digital data representing digital radiographic images into a display map representing the absolute thickness of a region of the object, the system comprising:

• a. a radiation source for directing X-ray or gamma ray radiation through a region of an object;
• b. a radiation detector having a plurality of sensing elements for detecting said radiation;
• c. means for acquiring a flat field image to equalize a response from each said sensing element;
• d. means for recording numerical data indicative of an intensity of said radiation incident on each said sensing element;
• e. means for correlating said numerical data to a measurement of the thickness of said object;
• f. means for calibrating said numerical data, comprising:
• i. means for correcting for variations in a source-detector-distance (SDD) between said source and said detector;
• ii. means for correcting for variations in a source-object-distance (SOD) between said source and said object;
• iii. means for correcting for variations in a spatial frequency response (MTF) of said detector;
• iv. means for correcting for variations in a geometric profile defining said object;
• and
• g. means for generating a map representing an absolute thickness of the region of the object from said calibrated data.

A method for calibrating digital data and using the data to generate a thickness map of an object, comprising the steps of:

• providing an X-ray gamma ray radiation source and radiation detector;
• providing a calibration block having a plurality of thickness regions disposed along a length of said block;
• acquiring a digital image with said radiation detector representing each of said thickness regions;
• detecting the boundaries of each said thickness region;
• sampling an inner area of said image at each said thickness region so as to generate a mean pixel value and an uncertainty representing each said thickness region;
• mapping each said mean pixel value to a thickness dimension defining each said thickness region;
• generating a look-up table to store results from said mapping step;
• and
• generating a thickness map using the look up table.