Po‐Thur Eve General‐19: Energy dispersive x‐ray diffraction system: Analysis of noise at low momentum transfer arguments

An energy dispersive x‐ray diffraction system has been built to measure the diffraction signals of breast tissue. The diffraction signals are a function of the momentum transfer argument, x =( E /hc)sin(θ/2), where E = photon energy and θ = scatter angle. The current system has noise problems for signals measured at x < 1.3 nm −1 where it is anticipated that most of the contrast exist for diagnosing normal breast tissue versus cancerous tissue. For a 5 mm thick 5 mm diameter water sample, the scatter signals at low x obtained at 9° with a 3 mm diameter 50 kV beam are about 70% higher than what are to be expected. Values at higher x values are however in good agreement with those in the literature. In this work we measured the scattered field from the pinhole since it could contribute to the large signals at low x values. The scattered count rates were measured at angles of 2 to 15 degrees in the usual way. For smaller angles including zero we used a 1.5 mm by 1.5 mm beam stopper centered at the bottom of the pinhole. A 100 μm diameter W aperture was placed above the detector and the field was sampled at various locations in the shadow of the beam stopper. The results suggest that the scatter from the pinhole could increase the diffraction signals at low x by 6%. Based on these findings we intend to revisit our measurement of the incident spectrum and the multiple scatter.