sCMOS rolling shutter compensation for dynamic micro-computed tomography.

Objective.To develop a pixel-row-specific retrospective gating technique for dynamic micro-computed tomography (micro-CT) imaging that removes motion artifacts introduced by rolling shutter acquisition on scientific complementary metal-oxide-semiconductor detectors.Approach.The proposed by-row gating technique-which accounts for the differences in acquisition timing of individual rows of pixels in each projection frame-is compared to the conventional method of by-frame gating wherein all pixels of a frame are assumed to have been acquired simultaneously. The errors associated with each gating method are demonstrated analytically, numerically (by simulated scanning of a dynamic phantom), and experimentally (by scanning an inflatable object and anex vivolung sample).Main results.By-row gating minimizes phase errors in the projection image domain prior to reconstruction, resulting in images with less out-of-phase motion, reduced motion artifact, and higher spatiotemporal resolution. Phase errors produced from by-row gating are determined only by the constraints of detector integration time and reconstructed phase bin width. Conversely, when gating by frame, spatially varying phase errors in the projection image domain are propagated into the reconstructed images, resulting in out-of-phase motion and motion artifacts that increase in severity with distance from the center of rotation. The magnitude and spatial pattern of this error depend on the ratio of object phase rate to frame acquisition rate, beam collimation and rolling shutter orientation.Significance.We identify two key parameters that determine the severity of micro-CT imaging artifacts caused by rolling shutter acquisition, and we provide an algorithm for by-row gating that eliminates artifacts and can be implemented on any rolling shutter system. By-row gating outperforms conventional by-frame gating, enabling accurate reconstruction of high-speed phenomena without compromising the high spatiotemporal resolution necessary to study microstructural dynamics.