Evaluation of frequency multiplexing radiography based on multi-pixel x-ray technology

摘要

We have recently demonstrated the feasibility of frequency multiplexing radiography (FMR) technique based on the frequency division multiplexing (FDM) principle and the carbon nanotube field emission x-ray technology. The key component of the FMR technique is a multi-pixel carbon nanotube field emission x-ray source. The prototype multi-pixel x-ray source has a linear array of nine field emission x-ray pixels. By programming the control electronics, the multi-pixel x-ray source can generate spatially and temporally modulated x-ray radiation. During the multiplexing imaging process, all the x-ray pixels were turned on simultaneously with each beam modulated at different frequency. The superimposed x-ray signals generated by the multi-pixel x-ray source were captured using a high speed flat panel x-ray detector over a certain period of time. The collected composite images were then demultiplexed using a Fourier transform based algorithm to recover the original nine projection images from different view angles. The FMR technique can in principle increase the imaging speed and reduce the x-ray peak workload for applications such as computed tomography (CT). In this paper we evaluated the performance of this new radiographic imaging technique based on our simulation and experiment results. Imaging artifacts caused by the cross-talk among different frequency subchannels have been studied and the importance of orthogonal frequency division multiplexing (OFDM) has been demonstrated.