The Characterisation of a Secondary Fluorescence X-ray Tube for Medical Imaging, Security Screening and Analytical Applications

Describes the characterisation of a new prototype secondary fluorescence X-ray tube. This tube allows the user to interchange the secondary target, and thus select the X-ray tube spectrum. Measurements of the focal spot size, intensity the K/spl alpha/ fluorescence lines and the spectral purity of the source are presented for a range of secondary targets including tantalum, tungsten, silver, copper and a rhodium layer on tungsten. Measurements with the tantalum target confirmed that the intensity from the new Fluorex tube was of the same order as measured previously (8.5/spl times/10/sup 5/ photons/s/mm/sup 2/ source area into 1/spl times/10/sup -4/ sr) at 160 kV and 3.75 kW. This was found to be approximately 30-40 times less than the flux into a comparable energy window containing the K/spl alpha/ emission lines of a conventional tungsten anode X-ray tube operating at 140 kV and 3.75 kW.