| 摘要 |
<p>A method and apparatus for calibrating detectors (44) in a computed tomography (CT) system (40) to compensate for differential errors in the detectors are disclosed. Multiple sets of scan data are acquired for a phantom (102, 102A, 102B) at multiple thicknesses of the phantom (102, 102A, 102B). The phantom (102, 102A, 102B) can be made from multiple slabs of material positioned on the scanner table in a horizontal orientation or in a vertical orientation. Horizontal slabs (102) are removed or added to the stack of slabs to vary the thickness of the phantom (102, 102A, 102B). With vertically oriented slabs (102A, 102B), each slab is of a different height such that scans of different slabs produce X-ray data for rays having different path lengths and, therefore, attenuations. For each detector (44), errors in the scan data at the multiple phantom thicknesses are identified and fit to a parametric equation with respect to the log attenuation associated with each thickness. In one embodiment, the parametric equation is a quadratic polynomial. The polynomial is used during subsequent scanning of actual objects (50) to adjust attenuation measurements.</p> |
