A multi-frequency EIT system design based on telecommunication signal processors.

Abstract:

:A multi-frequency electrical impedance tomography system for cardiopulmonary monitoring has been designed with specialized digital signal processors developed primarily for the telecommunications sector. The system consists of two modules: a scan-head and a base-station. The scan-head, located close to the patient's torso, contains front-end circuits for measuring transfer impedance with a 16-electrode array. The base-station, placed at the bedside, comprises 16 direct digital synthesizers, 32 digital down-converters, digital circuits to control the data acquisition sequence and a USB-2.0 microcontroller. At every step of the scan sequence, the system simultaneously measures four complex variables at eight frequencies. These variables are the potential difference between the selected pair of sense electrodes, the currents applied by the source and sink electrodes, and the current flowing through the ground electrode. Frequencies are programmable from 10 kHz to 2 MHz with a resolution of 2 mHz. Characterization tests were performed with a precision mesh phantom connected to the scan-head. For a 5 Hz frame rate, the mean signal-to-noise ratio and accuracy are, respectively, 43 dB and 95.4% for eight frequencies logarithmically spaced from 70 to 950 kHz. In vitro and in vivo time-difference images have been reconstructed.

journal_name

Physiol Meas

authors

Robitaille N,Guardo R,Maurice I,Hartinger AE,Gagnon H

doi

10.1088/0967-3334/30/6/S04

subject

Has Abstract

pub_date

2009-06-01 00:00:00

pages

S57-71

issue

6

eissn

0967-3334

issn

1361-6579

pii

S0967-3334(09)00941-1

journal_volume

30

pub_type

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