Multiplexing technique has been widely used in telecommunication, magnetic resonance imaging (MRI) and
various spectroscopic applications to drastically increase system throughput. In the field of radiology, however, it was
just getting started to attract researchers' attention recently due to the development of multi-beam x-ray source
technology, especially the emergence of carbon nanotube (CNT) field emission based multi-beam x-ray source. The
CNT multi-beam x-ray source provides an ideal signal source for multiplexing x-ray imaging applications because of its
capability of modulating x-ray radiation waveforms. The feasibility of multiplexing x-ray radiography has been
successfully demonstrated experimentally using a CNT field emission enabled multi-beam x-ray imaging system. The
idea of applying multiplexing radiography in computed tomography (CT) to speed up scanning speed has also been
proposed. At the same time several simulation studies on the evaluation of multiplexing x-ray imaging performance have
been reported. In this study, we reported our recent investigation on the imaging quality assessment of multiplexing xray
radiography based on the simulation work stimulated by our previous experimental experience. A computer program was written to simulate the imaging process of the as-developed multi-beam x-ray imaging system. The impacts of different noise components on multiplexing imaging quality were studied. Our preliminary results indicated that the performance of multiplexing x-ray radiography is closely related to the noise environment and x-ray tube current stability. Under appropriate imaging conditions, multiplexing radiography has the potential to achieve higher imaging speed without significantly sacrificing the imaging quality.
As a widely adopted imaging modality for pre-clinical research, micro-CT is constantly facing the need of providing
better temporal as well as spatial resolution for a variety of imaging applications. Faster CT scanning speed is also
preferred for higher imaging throughput. We recently proposed a gantry-free multi-beam micro-CT (MBμCT) design
which has the potential to overcome some of the intrinsic limitations of current rotating-gantry CT technology. To
demonstrate its feasibility, we have constructed a testing system with a multi-beam field emission x-ray (MBFEX)
source array with a linear array of 20 individually controllable x-ray emitting pixels. Based on simulations of the electron
optics and preliminary experimental measurements the design of the MBFEX source has been further optimized. The
newly designed imaging system has been characterized and commissioned following our standard imaging protocol. It
has clearly shown improved system stability and enhanced imaging capability. As a result of reduced mechanical
rotation during imaging acquisition, we are expecting to achieve higher CT scanning speed without significantly
sacrificing imaging quality. This prototype MBμCT system, although still in its early development phase, has been
proved to be an ideal testing platform for the proposed gantry-free micro-CT scanner.
Current micro-CT scanners use either one or two x-ray tubes that are mechanically rotated around an object to
collect the projection images for CT reconstruction. The rotating gantry design hinders the performance of the micro-CT
scanner including the scanning speed. Based on the newly emerged carbon nanotube based distributed multi-beam x-ray
array technology, we have proposed to build a stationary gantry-free multi-beam micro-CT (MBμCT) scanner. To
investigate the feasibility of this concept, a prototype system using a source array with 20 individually controlled x-ray
beams has been designed and tested. The prototype CT scanner can generate a scanning x-ray beam to image an object
from different viewing angles (coverage of 36°) without any rotation. The electronics and software for system control
and data have been implemented. The projected performance of the prototype MBμCT imaging system was discussed
and some preliminary imaging results were presented.
A prototype physiologically gated micro-computed tomography (micro-CT) system based on a field emission
micro-focus x-ray source has been developed for in vivo imaging of small animal models. The novel x-ray
source can generate radiation with a programmable waveform that can be readily synchronized and gated with
non-periodic physiological signals. The system performance is evaluated using phantoms and sacrificed and
anesthetized mouse models. Prospective respiratory-gated CT images of anesthetized free-breathing mice are
collected using this scanner at 100msec temporal resolution and 10 lp/mm of 10% system MTF.
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