Desktop micro-CT with a nanotube field emission x-ray source for high-resolution cardiac imaging

We have previously reported the development of a dynamic micro-CT scanner with a stationary mouse bed using a compact carbon nanotube (CNT) field emission x-ray tube and preliminary results on its utility for prospectively gated cardiac imaging. In this paper we report the recent progress in improving the performance characteristics of this scanner. Through optimization of the CNT cathode, the stable emission current has been increased. The output power of the CNT x-ray source has reached similar to 100W peak power at 100 mu m focal spot size. The higher flux enables improvement of the x-ray energy spectrum to minimize the beam hardening effect and increasing the system temporal resolution by using shorter x-ray exposure time. The scanner's temporal resolution has been increased to similar to 10 msec, which is sufficient for high-resolution micro-CT imaging of mouse heart and lung under free-breathing setting. The spatial resolution is maintained at 6.2 lp per mm at 10% system MTF. The nanotube micro-CT scanner's application in mouse cardiac imaging has been demonstrated with high-resolution (80 mu m and 15 msec) micro-CT of the mouse heart under free-breathing setting.