TESTS OF VARIABLE-BAND MULTILAYERS DESIGNED FOR INVESTIGATING OPTIMALSIGNAL-TO-NOISE VERSUS ARTIFACT SIGNAL RATIOS IN DUAL-ENERGY DIGITAL SUBTRACTION ANGIOGRAPHY (DDSA) IMAGING-SYSTEMS

In recent work, various design techniques were applied to investigate the feasibility of controlling the bandwidth and bandshape profiles of tungsten/boron-carbon (W/B4C) and tungsten/silicon (W/Si) multilayers for optimizing their performance in synchrotron radiation based angio graphical imaging systems at 33 keV. Varied parameters included altern ative spacing geometries, material thickness ratios, and numbers of la yer pairs. Planar optics with nominal design reflectivities of 30-94% and bandwidths ranging from 0.6-10% were designed at the Stanford Sync hrotron Radiation Laboratory, fabricated by the Ovonic Synthetic Mater ials Company, and characterized on Beam Line 4-3 at the Stanford Synch rotron Radiation Laboratory. In this paper we report selected results of these tests and review the possible use of the multilayers for dete rmining optimal signal to noise vs artifact signal ratios in practical dual-energy digital subtraction angiography systems.