A novel fourth generation micro-CT (WATCH-CT) with a unique scanning geometry, that collects parallel projections from a standard x-ray source without the requirement to interpolate or rebin the data, is studied and evaluated for its imaging qualities and performance characteristics. For a comparative analysis of the WATCH micro-CT system and the conventional CT geometry, the local noise power spectrum and the modulation transfer function is derived from the same initial parameters. The spatial resolution (MTF), characterized by the response of the system, is determined by the MTF derived by the oversampling method. The calculations involve varying the parameters like the region of evaluation (ROE) position, FOV magnification, angular sampling, pixel size, filtration and reconstruction algorithm to provide an extensive analogy between these systems. The spatial resolution of the scanning geometries is evaluated and compared. The MTF curves illustrate a higher relative resolving capacity for the WATCH micro-CT compared to the conventional geometries which is due to the characteristics of this unique geometry. The WATCH system exhibits higher resolutions explicitly at the regions away from the center. The NPS curves of WATCH geometry shows higher noise content in comparison to the conventional geometry.
A new and simple object for calibrating tomographic scanners has been proposed. Instead of a conventional high-density ball as an object for calibration, we propose a high-density conic body. The cone is advantageous compare to the ball both because of its easy availability (uncomplicated manufacturing) and the straightforward and less error-prone analysis necessary for the identification of a space point (ball’s center vs. cone apex). Applying the conic body instead of a ball as a calibration object enables to reduce calibration errors substantially. Additionally we propose an efficient way to determine the discrepancy between ideal and misaligned positions of the detector that may be crucial for the quality of the reconstruction.
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