SU-GG-J-16: A Physiologically Gated Micro-CT Scanner for Dynamic Small Animal Imaging Based On a Carbon Nanotube X-Ray Source

Abstract

Purpose: Current commercial micro‐CT scanners have the capability of imaging objects ex vivo with high spatial resolution, but performing in vivo micro‐CT on small animals is still challenging because their physiological motions are at least ten times faster than those of human. The purpose of this research is to develop a respiratory and cardiac gated micro‐CT scanner with both enhanced spatial and temporal resolutions, and more versatile imaging capabilities for in vivoimaging of small animal models. Method and Materials: A physiologically gated micro‐CT scanner was constructed based on a carbon nanotube micro‐focus x‐ray source. The scanner consists of a carbon nanotube x‐ray source, a flat panel x‐ray detector, and a rotation sample stage aligned in cone‐beam geometry. The dynamic gating was achieved from a small animal physiological monitor system plus some home‐made gating electronics. The spatial and temporal resolutions of the scanner were evaluated by MTF analysis and temporal analysis, respectively. Cardiopulmonary gated micro‐CT images were collected and analyzed on several anesthetized free‐breathing mice to evaluate the system's performance. Results: The scanner was found to have 50 microns spatial resolution and ∼20 milliseconds temporal resolution. Imaging sequences were readily synchronized and gated to non‐periodic physiological signals of free‐breathing mice. Quantitative physiological measurements can be obtained from the four‐dimensional micro‐CT results for the cardiopulmonary organs of the mice. Conclusion: We have developed a physiologically gated micro‐CT scanner based on a carbon nanotube micro‐focus x‐ray source. The scanner can easily acquire images at the desired cardiopulmonary phases with fast temporal resolution and minimized delay. The high spatial and temporal resolutions of the micro‐CT scanner make it well suited for in vivoimaging of small animal models. The system performance can be potentially enhanced through further development of a carbon nanotube micro‐focus x‐ray tube with higher flux.