Apparatus for measuring xenon concentration in xenon cerebral blood-flow studies

摘要

Apparatus for measuring xenon concentration in xenon cerebral blood-flow studies operates under the control of a microprocessor which is used to monitor the patient's breathing cycle and to control a sampling pump in order to assure that only end-tidal gas is sampled. A xenon gas mixture is delivered to a patient by means of a mask assembly. At the end of each exhale cycle, the patient's end-tidal gas is held in a chamber on the exhale side of the mask assembly. At the start of the next inhale cycle, the microprocessor activates the sampling pump which draws end-tidal gas into a thermal conductivity detector. The output of the detector is transmitted through an A/D converter and the resultant value stored in the microprocessor memory along with the time of the sample. At the completion of a CT scan series, the accumulated data in the microprocessor is transferred to the CT-system-housed computer to be used in the reconstruction of cerebral blood-flow images using conventional techniques.