A portable x-ray source with a nanostructured Pt-coated silicon field emission cathode for absorption imaging of low-Z materials

被引:75
作者
Basu, Anirban [1 ]
Swanwick, Michael E. [1 ]
Fomani, Arash A. [1 ]
Velasquez-Garcia, Luis Fernando [1 ]
机构
[1] MIT, Microsyst Technol Labs, Cambridge, MA 02139 USA
关键词
field emission; medical imaging; silicon field emitter array; x-ray generation; CHEMICAL-VAPOR-DEPOSITION; COMPUTED-TOMOGRAPHY; EMITTER ARRAYS; MASSIVE ARRAYS; UNIFORM; ENERGY; CT; QUALITY;
D O I
10.1088/0022-3727/48/22/225501
中图分类号
O59 [应用物理学];
学科分类号
摘要
We report the design, fabrication, and characterization of a portable x-ray generator for imaging of low-atomic number materials such as biological soft tissue. The system uses a self-aligned, gated, Pt-coated silicon field emitter cathode with two arrays of 62 500 nano-sharp tips arranged in a square grid with 10 mu m emitter pitch, and a natural convection-cooled reflection anode composed of a Cu bar coated with a thin Mo film. Characterization of the field emitter array demonstrated continuous emission of 1 mA electron current (16 mA cm(-2)) with >95% current transmission at a 150 V gate-emitter bias voltage for over 20 h with no degradation. The emission of the x-ray source was characterized across a range of anode bias voltages to maximize the fraction of photons from the characteristic K-shell peaks of the Mo film to produce a quasi-monochromatic photon beam, which enables capturing high-contrast images of low-atomic number materials. The x-ray source operating at the optimum anode bias voltage, i.e. 35 kV, was used to image ex vivo and nonorganic samples in x-ray fluoroscopic mode while varying the tube current; the images resolve feature sizes as small as similar to 160 mu m.
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页数:11
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