适用于微型CT系统活体成像的新型门控技术

New Gating Technique for Imaging of Micro-CT system in Vivo

目的微型CT(Micro-CT)具有解剖成像及无损伤的特点,但对软组织分辨率较低,且在活体成像中,动物呼吸和心脏运动会引入伪影。为提高图像质量,本文提出一种新型门控技术。方法门控技术通过检测动物的心肺运动,在其某个生理时相产生门控信号,并触发X射线球管曝光,最终将获得的投影图像用于三维重建。心肺门控系统主要由监控软件,数字信号处理器(DSP),心电(ECG)检测电路及热电偶电路组成。结果在小鼠活体实验中,获取了6组采用不同门控信号得到的CT投影数据。结论实验结果表明,心肺门控技术的使用,极大地提高了小动物在自由呼吸状态下,使用Micro-CT系统进行活体成像的图像分辨率。

Objective Micro X-ray computed tomography （Micro-CT） is characterized as anatomical imaging and fully noninvasive. However, it is a tough job to make images of the soft tissues with high resolution,especially in the abdomen and thorax, the artifacts are induced by respiratory and cardiac motion. In view of that, a new gating technique is proposed. Methods Gating technique produced gating signals based on animal’s cardiac-pulmonary motion in real time to trigger the X-ray bulb and assured that each projection was acquired in the animal’s certain physiological phase. The projections were used to reconstruct 3 dimensional mages. This non-invasive gating system consisted of monitor software, a digital signal processor, an electrocardiography （ECG） detection circuit and a thermocouple circuit. Results In vivo mouse experiments were performed and 6 projection data sets with different gating signals were acquired. Conclusion The results show that application of the gating technique has greatly improved the resolution of the image for the free breathing small animals.