Off-Axis Spectral Distribution Variation of Diagnostic X-Ray Tube for Different Anode Angles

Abstract

The x-ray tubes have a function to generate x-ray photons when electric energy is supplied. The geometrical design of the x-ray tube has a property to determine the fundamental characteristics of the x-ray beam, such as x-ray beam uniformity, focal spot size and the spectrum of x-ray energy. These features of the x-ray beams are very important due to the effect of radiological parameters, such as image contrast, spatial resolution, and the patient dose. The x-ray spectra from the x-ray tubes are simulated and measured by number of people according to their research need. Currently accessible x-ray source models provide the spectral distribution along angular dimensions (x-axis, y-axis) solely at the central axis of the beam for different anode angles. spectrally accurate x-ray beam model in image reconstruction may help to improve material identification and quantification. Using an inaccurate x-ray model in spectral reconstruction can lead to severe artifacts, one of the examples is the well-known beam-hardening artifacts. Therefore, the aim of this study is to investigate the off-axis spectral distribution variation for different anode angles by using a Monte Carlo simulation tool. This study will help to improve the material discrimination in the existing spectral CT systems consequently will lead to the better diagnosis. Future work includes the incorporation of this model into MARS spectral reconstruction. Extension of this model for various voltage and for various anode materials will also be an area of future interests.