Sci‐Fri AM General‐09: Pseudo‐Monoenergetic X‐Ray Diffraction Imaging using Balanced Filters

In the treatment of kidney stones, knowing stone composition has been established as an important aid to the understanding of stone formation and in preventing recurrences, particularly the composition of the initial “core” of the stone. Traditionally, stone composition has come from laboratory techniques such as infrared spectroscopy and x‐ray diffraction. These methods require taking multiple samples of excised stone fragments and powdering them — losing structural information in the process. Furthermore, since stone composition is rarely homogenous, samples must be drawn from enough materially distinct regions of the stone or some components may not be identified. Low‐angle coherent scatter (CS) at diagnostic energies provides tissue‐composition information that can distinguish between different biological materials. Previously, our lab has developed a system to capture these CS patterns and to match them to known patterns of pure component materials. A drawback of the system is that it uses a polyenergetic x‐ray source. Since the CS angular distribution is energy‐dependent, an angular blurring of the measured cross section occurs, impairing the system's ability to accurately identify composition. To overcome this drawback, the spectral width of the x‐rays must be reduced. One way to achieve this uses two filters to create two CS patterns, which are then subtracted. If the filters are chosen with similar atomic numbers, the subtracted scatter pattern will be formed primarily by x‐rays in a narrow energy range. In this article we present an application of this “balanced filter technique” that will improve the scatter pattern uniqueness of kidney stone components.