A study of an areas x-ray source for Diffraction Enhanced Imaging for Clinical and Industrial Applications

Abstract

Research in diffraction-enhanced imaging (DEI) has shown strong potential in obtaining high-resolution images as compared to conventional radiographs. A successful development of a compact size DEI system would greatly improve x-ray diagnostics in the medical field, as well as potential application in material science research and other industrial applications.

DEI experimental research, using a synchrotron source, has shown success and proven to be an attractive medical diagnostics method. While the use of a synchrotron source might be applicable, however, a clinical system would rather use an x-ray source that could be integrated into a radiology system feasible for hospital and clinical practices.

This research is aiming to develop an area x-ray source that replaces the need for a synchrotron source by providing a monochromatic area x-ray beam collimated over 100cm2 area. Reasonable operation time (5-10 sec) is also a desirable feature with efficient thermal management of the x-ray tube (target and housing). The x-ray flux should be comparable to synchrotron source flux (1.4 x 1012 photon/mm2/sec). The peak power must not exceed 200kW for feasible use in a major medical facility or industrial complex. A computational study of concentric filament area x-ray source has been investigated in this research.

The design features are based on generating electrons from three concentric circular filaments to provide an area electron flux, with a 60kV accelerating potential. The x-ray target is a grounded stationary oxygen-free copper target with a layer of molybdenum (manufactured by BranXray Co., Inc.). Study of electron trajectories and their distribution at various tilt angles of the target was completed using the SIMION 3D code. Heat loading and thermal management is studied using an in-house developed thermal and heat transfer code. X-ray flux and energy distribution for aluminum and beryllium windows was studied using MCNP 4C2 Monte Carlo code. A prototype area x-ray source, a proof-of-principle device, is under construction in the Department of Nuclear Engineering, NCSU to investigate the feasibility of area x-ray generation and the scalability to clinical and industrial aspects. Other researchers will use the computational results of this thesis as a predicting tool to determine and optimize the prototype device operational parameters, and to benchmark the experimental results.