Retrospective gating

Step-and-shoot respiratory or cardiac gated images are readily available from many Cone beam geometry microCT scanners on the market today. While admittedly the simplest method to acquire multiphase image data, step-and-shoot scan methods can spend upwards of 50% of the scan time simply accelerating and decelerating gantry equipment. A free-running acquisition mode, on the other hand, accelerates the gantry only at the beginning and end of the scan, so less time is wasted. One downside of this free-running mode, however, is that acquired raw image data needs to be sorted according to phase prior to image reconstruction, and there’s little or no guarantee that images will be acquired at precisely the correct phase at all. Based on recently published methods , we’ve been experimenting with a post-scan retrospective gating method implemented on the GE Locus Ultra preclinical scanner, and the image above demonstrates an example result: 10 phases were reconstructed automatically using our GPU reconstruction engine, running on our custom workstation . The total scan acquisition time was 50 seconds, during which time the CT scanner made 10 full rotations. The total reconstruction time was 86 seconds. While our initial goal is to produce a turn-key third-party solution for the Ultra scanner, there’s no reason why this can’t be extended to other hardware platforms; we’ll be investigating other scanners, which don’t currently have such gating options, in the upcoming months.