Hyoung K Lee
Missouri University of Science and Technology, USA
Title: Compact X-ray tubes for stationary CT architecture
Biography
Biography: Hyoung K Lee
Abstract
For imaging arrhythmia patients with cardiac computed tomography (CT), a temporal resolution <50 msec is desired, which cannot be delivered by conventional CT architectures with a rotation gantry. By eliminating the physical rotation of the gantry and electronically sweeping x-ray beams across the gantry, stationary CT architecture can achieve a temporal resolution <50 msec. Stationary CT architecture utilizes a stationary gantry comprising separate arrays for distributed x-ray sources and detectors (Fig. 1). These individual x-ray sources are required to be compact, fast, and individually addressable in order to acquire 200+ projections for successful CT reconstruction and achieve a temporal resolution <50 msec. A compact x-ray tube that fits these requirements is being developed.
The aim of the present research was to develop and study the first-generation prototype compact x-ray tube primarily consisting of a CNT-based cold cathode and a transmission type anode (Fig. 2). Monte Carlo simulations were conducted to compare tungsten, molybdenum, and rhodium as target materials and to optimize the target thickness for a transmission type anode. Using a particle-in-cell technique, the electron focusing was studied to design an electrostatic focusing lens for achieving <1 mm focal spot size (FSS) of x-ray generation in the prototype. The prototype was studied experimentally to understand the performance of the prototype and its control parameters. The results of these simulations and experiments showed the following: CNT-based cold cathode can generate electron pulses with frequencies up to hundreds of kilohertz; an electrostatic lens can achieve the required <1 mm FSS; the lens aperture, thickness, and location can be used as a coarse control on the FSS, while the lens potential can be used as a fine control; and x-ray energy spectra from a transmission type anode is similar in shape to the energy spectra from a conventional reflection type anode after filtration.