| 摘要 |
In a computed tomography system a cylindrical calibration phantom having a vertical and a horizontal crosshair on its front face is adjusted until the intersection point of the crosshairs is coincident with the isocenter of the x-ray scanner as demonstrated by the display of a reconstructed tomographic of the phantom. Vertical and horizontal intersecting coherent light beams from a laser source are then projected onto the phantom and the source is adjusted until the light beams, crosshairs and their intersections coincide. Any phantom used for any subsequent calibration only needs to be adjusted until the permanently set laser light beams coincide with its crosshairs in which case the isocenter is determined exactly again and the apparatus is ready immediately for a calibration run.
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