By shifting the rotary axis and the measured object relative to the X-ray unit (source and sensor), the magnification can be adjusted for work piece size and tolerances.   In this manner, small objects or segments of objects can be measured at high magnification and large objects can be captured completely in the field of view.  The selection of magnification has a particularly pronounced effect on the resolution attained when capturing the work piece.  This is first influenced by the size of the image points in object coordinates (pixel size).  The resolution is also affected by the size of the focal spot (blurring), the quality of the rotary axis, and other characteristics of the machine components.  The geometric parameters for a particular magnification like the position of the X-ray source, X-ray sensor and rotary axis, are determined using suitable calibration processes.  These parameters are then applied to the subsequent calculations.

See in image above adjusting magnification by changing the distance between the object and the X-ray components: a) Low magnification b) High magnification