<title>Semitransparent monochromators for x-ray imaging based on highly oriented pyrolytic graphite (HOPG)</title>

Abstract

ABSTRACT Semitransparent HOPG monochromators are being investigated with an emphasis on their potential applications in X-rayimaging systems. HOPG plates and films, 5-100 jtm thick and up to 14 cm2 in area, were tested. Scanning techniques wereused to measure the profiles of local reflectivity and transparency at different monochromator thicknesses. Mosaic spread,AU), down to 3.6 was recorded. HOPG film areas with average Aa=5 and 6' were equivalent to 4.5 and 10 cm2 respectively.The echelon monochromator arrangement produced a sharp increase in reflectivity leading to the possibility of primary beam sweeping. Results to date are very promising for future applications in fields such as medical diagnostics and surgical treatments monitored using digital X-ray cameras.Keywords: Semitransparent monochromator, HOPG, X-Ray imaging 1. INTRODUCTION In biomedical applications, decreasing dose rates is one of the basic goals in the design of penetrating radiation systems'. Producing high contrast images using near K-jump absorption2 is another important criteria. As an example, duringangiography it is especially desirable to obtain crisp and clear images of vessels without shadows introduced by otherbiological tissues. Both problems are directly addressed by the development of effective systems capable of converting