Analysis of fast kV-switching in dual energy CT using a pre-reconstruction decomposition technique

Fast kV-switching is a dual energy acquisition technique in CT in which alternating views correspond to the low and high tube voltages. Its high temporal resolution and its suitability to a variety of source trajectories make it an attractive option for dual energy data acquisition. Its disadvantages include a one view mis-registration between the data for high and low voltages, the potential for poor spectrum separation because the fast kV-switching waveform may be more like a sine wave than the desired square wave, and the higher noise in the low voltage data because of the technical difficulty of swinging the tube current to counter the loss of x-ray production efficiency and loss of penetration at lower tube voltages. These issues are investigated with a recently developed pre-reconstruction decomposition method by the authors. Results include that symmetric view matching eliminates streaks from the view mis-registration, a sinusoidal waveform swinging between 80 and 135 kV gives sufficient spectrum separation, and that contrast-to-noise for the simulated imaging task maximizes at monochromatic energy of 75 keV.