Methods and apparatus for calibrating CT x-ray beam tracking loop

A Computed Tomographic (CT) imaging comprising:

• a movable collimator positionable in steps;
• a detector array comprising a plurality of detector elements arranged in rows and channels, the rows extending from a detector A-side to a detector B-side;
• and
• a computer coupled to said collimator and said detector array, said computer configured to:
• determine a detector A-side and a detector B-side target beam position;
• compute a plurality of Z-ratio curves corresponding to a plurality of detector rows and channels;
• and
• compare the Z-ratio curves at the detector A-side and detector B-side target beam penumbra positions to determine the optimal Z-ratio curve and corresponding detector channels and rows for controlling the X-ray beam positioning.

A machine readable medium having recorded, said machine readable medium installed on a CT imaging system including a movable collimator positionable in steps, and a detector array including a plurality of detector elements arranged in rows and channels, the rows extending from a detector A-side to a detector B-side, said machine readable medium configured to instruct a processor to:

• determine a detector A-side and a detector B-side target beam position;
• compute a plurality of Z-ratios;
• and
• compare the Z-ratio curves at the detector A-side and detector B-side target beam positions to determine the optimal Z-ratio curve and corresponding detector channels and rows for controlling the X-ray beam positioning.