Abstract
A four-channel magnetometer instrument is described. It has been developed to measure changes in diameters of the chest and abdomen during respiration. A linearisation correction allows for the magnetic field strength detected by the receiver being proportional to the inverse cube of the diameter being measured. Diameters and changes in diameter are measured to an accuracy of 4% (1 SD) over the working range (15-50 cm). The effects of non-ideal positioning and extraneous movements of the magnetometer coils, cross-channel interference and the influence of nearby metals are described. With minimal care in positioning the coils, these effects are negligible. The instrument has been in use for one year, assessing chest wall movement in patients with abnormal lung function. Recordings are presented illustrating typical normal and abnormal chest wall movements.
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Schedule a callMore From: Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics
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