Methods Determining the Angular Increment of A Continuous Scan Cone-Beam CT System

Abstract

X-ray cone-beam computed tomography (CBCT) imaging based on the single circular orbit scan mode has become more and more popular because of its high imaging speed. Generally the X-ray source and detectors are stationary and the scanned object rotates step by step over 360 in this kind of system. In order to improve the imaging efficiency, the step rotation is sometimes replaced by the continuous rotation. For this continuous rotation, if there is an error about the number of projection images over 360 caused by the uncertainty of synchronization between the detector and the mechanical sub-system, the angular increment for the CT reconstruction may not be known exactly. The error will lead to serious artifacts in the CT images. This paper describes two possible methods determining the angular increment. Both of them are based on the statistical similarity among the projection images. They determined the angular increment by calculating the correlation coefficients and the standard deviation of the difference image between the image at 0 and the images at other angular positions. These two methods can verify each other. We performed numerical studies and experiments to demonstrate and validate the proposed approaches. Results in these studies and experiments confirm that the proposed two methods can determine the right projection number and the angular increment. The proposed approaches may find applications in CBCT system with continuous single circular orbit scan mode.

Towards efficient application-dependent dimensional measurements with computed tomography: optimized reduction of measurement duration using continuous scan mode: experimental investigations

“…An investigation by Fischer et al (2017) only investigated the continuous scan mode as an influencing factor among many, and did not systematically study the influence of the positioning or projection number for the con- tinuous scan mode (Fischer et al, 2017). Furthermore, the influence of angle-of-rotation deviations on the reconstruction has been examined, and methods for determining the angular increment have been derived from this (Fu et al, 2010). However, to the best of the authors' knowledge, the quantitative influence of the number of projections and workpiece position on the measurement result in continuous scan mode for dimensional industrial X-ray CT still represents a research gap.…”

Multi-Mounted X-Ray Computed Tomography

“…Dual source CT [ 30 ] achieves a larger temporal resolution improvement. Single circular orbit cone-beam CT (CBCT) permits the production of hundreds of slices in parallel in a single gantry rotation and is regularly used to achieve high scanning efficiency [ 15 , 20 , 31 – 34 ]. Inverse geometry CT with stationary source array (SS-IGCT) [ 27 , 35 , 36 ] has been recently proposed to image a large volume of interest with minimal cone-beam artifacts and with very high temporal resolution.…”

Fast local reconstruction by selective backprojection for low dose in dental computed tomography

“…This algorithm was developed for image reconstruction on PI-line segments [4] in a helical cone-beam scan, and it provided a strategy for reconstructing the exact region of interest (ROI) using truncated data [5][6][7][8][9][10][11]. Because the circular scanning trajectory is easy to implement and control in practice, it is widely used in CT [12]. Based on the concept of virtual PI-line and virtual circular orbit, Yu et al modified the BPF algorithm to reconstruct images in a circular cone-beam scan [13].…”