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In order to extract the impedance information at different frequencies in our multi-frequency electrical impedance tomography (EIT) system, a digital demodulation method was employed. Theoretically, this method can improve the SNR by √(N/2) times, if we sampling N point per period. Moreover, as very little system resources been needed in this method, all the calculating operations can be finished...
An electrical impedance scanning (EIS) system was studied to meet the requirement of clinical breast screening. A quick examination, easy operation, safe electrical isolation and obvious diagnosis results are four main factors to a screening system. Basing on these considerations, a multi-frequency signal sampling system controlled by ARM chip was setup and the measuring data were transmitted to PC...
A new post-processing algorithm was developed for EIS image in order to improve the accuracy of diagnosis. This algorithm automatically analyzes data and recognizes the light region in the EIS image basing on the data process criterions. The threshold criterion and the modality criterion were derived from the ideal saline-tank phantom experiment. And the filter criterion came from the analysis of...
A 16-channel magnetic induction imaging system is introduced briefly. Highly precise phase and magnitude detecting method is applied to the information acquisition. The resolution of phase detecting is 0.003deg. The results of magnitude detecting also provide us with useful information. The characteristic curves are smoother than that of our previous system. One dimension results in different positions...
An image monitoring system using electrical impedance tomography (EIT) for intraperitoneal bleeding was designed (FMMU V3.5). It consists of a constant current driving source with frequency of 50 KHz, a high accuracy measurement module, a driving and measuring mode program-controlled circuits, a data acquisition card, an optoelectronic isolated digital I/O board, and a custom-specified linear power...
To seek a single source drive pattern that is more suitable for brain electrical impedance tomography (EIT), a comparison between adjacent, cross, polar and newly proposed quasi-polar drive patterns was made in aspects of boundary voltages dynamic range, independent measurement number, total boundary voltage changes and anti-noise performance based on an equivalent circuit of the brain resistivity...
It is found that electrical impedance tomography(EIT) is promising in its application to the clinical image monitoring and that the back-projection algorithm of EIT can meet the preliminary requirements of the real-time monitoring through our work. In order to improve the computed speed and the imaged resolution, different ways of completing the algorithm were tried in this paper. Moreover, it is...
Electrical impedance scanning (EIS) is a new adjunctive diagnostic method for women breast cancer examination. In clinic research, we found some influencing factors which can induce a bad EIS imaging results. In order to analyze the influencing factors on EIS imaging and find the solutions, we set up an EIS workbench which can simulate the influencing factors that may happen in a clinic. We studied...
To establish a high precision data acquisition system for multi-frequency electrical impedance tomography (EIT), a series of methods were introduced. Those methods include building a driving signal with up to four frequency components to diminish the effect of the dynamic change of tissues resistivity, extracting the impedance information by a digital demodulator that can improve the SNR by 8 times...
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