Improved control of respiration during computed tomography by feedback monitoring.

The use of computed tomographic (CT) attenuation measurements to characterise lung pathology is hindered by the wide variations occurring with respiration. A simple strain-gauge has been used as a respiratory monitor with feedback to the patient giving a visual indication of chest expansion during CT. Significant improvement was achieved in reproducibility of mean attenuation values of nominally identical lung sections when the gauge was used as compared with control sections. Respiratory feedback monitoring has wide potential application in thoracic and upper abdominal CT.