A MULTILAYER MIRROR/MONOCHROMATOR FOR DUAL-ENERGY DIGITAL SUBTRACTION ANGIOGRAPHY

CURRENT SYNCHROTRON-BASED MEDICAL IMAGING FACILITIES EMPLOY NARROW (.05 - 1%) BANDWIDTH MONOCHROMATORS TO PRODUCE MONOCHROMATIC SOURCES OF HARD X-RAYS FOR DUAL-ENERGY DIGITALSUBTRACTION ANGIOGRAPHY. WE HAVE BEEN ABLE TO DEMONSTRATE THAT THE BANDWIDTH CAN BE INCREASED TO 5 TO 10% PROVIDED THAT THE TWO QUASIMONOCHROMATIC SOURCES ARE LOCATED AN APPROPRIATE DISTANCE IN ENERGY FROM THE IODINE K-EDGE. MULTILAYER MIRROR TECHNOLOGY OFFERS THE OPPORTUNITY TO PRODUCE DIFFRACTIVE ELEMENTS WITH BANDWIDTHS OF THIS ORDER. WE INTEND TO EXPLORE THE FEASIBILITY OF DESIGNING AND CONSTRUCTING A MULTILAYER MIRROR BASED MONOCHROMATOR FOR THIS IMPORTANT COMMERCIAL APPLICATION OF X-RAY TECHNOLOGY. WE HAVE SET THREE GOALS FOR OUR PHASE I RESEARCH PROGRAM: (1) DESIGN GRADED PERIOD MULTILAYERS SUITABLE FOR SYNCHROTRON-BASED DUAL-ENERGY DIGITAL SUBTRACTION ANGIOGRAPHY WITH 5 TO 10 PERCENT BANDWIDTH AND WITH OPTIMUM CENTER FREQUENCIES CALCULATED USING OUR IMAGE SIMULATION PROGRAM, (2) FABRICATE THE TWO GRADED MULTILAYERS BASED UPON THE DESIGN PARAMETERS DETERMINED UNDER GOAL 1, AND (3) MEASURE THE BANDPASS CHARACTERISTICS OF THE MULTILAYERS FABRICATED UNDER GOAL 2. OUR RESEARCH WILL CULMINATE IN THEDESIGN AND CONSTRUCTION OF A BROAD BANDWIDTH HARD X-RAY MONOCHROMATOR FOR DUAL-ENERGY SYNCHROTRON RADIATION ANGIOGRAPHY.