Abstract:
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Purpose: The modern day x-ray tube has undergone little change since its invention in the early 1900's. It has been recently demonstrated that carbon nanotubes may serve as effective field emitters in a cold cathode x-ray source, with specific advantages including precise x-ray exposure control to potentially reduce x-ray exposure and increase system resolution. Furthermore, there is the potential to create micro-focus x-ray sources. Our goal was to develop a micro computed tomography CT system based on this new nanotube based x-ray source for applications in small animal imaging.
Methods and Materials: A carbon nanotube based x-ray source was implemented with a triode gating structure, tungsten target and beryllium window. Maximum tube voltage was 40 kV with a current range of 0 to 500 microamps. A Hamamatsu C7921 detector was fixed opposite the x-ray source, with 50 x 50 micron pixel resolution and 1056 by 1056 pixels. Normal C57BL/6 strain, eight-week-old mouse carcasses were imaged. The animal was rotated in this setup with a rotary stage connected to a computer controlled stepper motor. (CT) reconstructions were performed offline with a modified fan-beam algorithm on 480 x-ray transmission images at 36kVp and 100 microampere current.
Results: CT images were reconstructed for a 5 x 5 x 5 cm FOV. Images demonstrated good reproduction of fine bony structure such as the skull, ribs and forepaw digits. Focal spot size of the x-ray source for the acquisition was estimated to be at 200 microns by 1000 microns. Further refinements in the x-ray focal spot size are ongoing.
Conclusion: Cold cathode carbon nanotube based x-ray sources offer clear advantages over the traditional tungsten filaments, including precise control of the x-ray source for high-resolution imaging and no need for a mechanical shutter to reduce x-ray dose.
Questions about this event email: yueh@alum.mit.edu
Lee MD, PhD, Y,
Novel Micro-CT based on a Carbon Nanotube Field Emission X-ray Source. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3108078.html
