Producing parallel x rays with a bent-crystal monochromator and an x-ray tube

A bent Laue monochromator and a conventional x-ray tube were used to produc e a fan beam that was parallel in the plane perpendicular to the plane of t he fan. The x-ray fan beam was tunable in energy and had about 12% energy b andwidth at a slice height of 5 mm when tuned to 50 keV. The beam's energy was slightly coupled to the vertical position on the beam's height. The sli ce height could be varied from I to 10 mm. The flux at 50 keV was approxima tely 2 X 10(6) photons/mm(2)/s with a rotating anode tungsten x-ray tube op erating at 120 kVp and 100 mA. The narrow energy bandwidth of the beam prod uced is advantageous over a conventional divergent polychromatic beam for a ll radiography applications, while the parallelism of the beam enhances its intensity by about threefold and offers some advantages for computed tomog raphy. (C) 2001 American Association of Physicists in Medicine.