AUTOMATIC CONTROL SYSTEM FOR RADIOACTIVE REGIONAL VENTILATION STUDIES

摘要

A system for obtaining a permanent visual record of the air passages of the lungs by the introduction of a measured quantity of air mixed with a radioactive gas such as Xenon (Xe133) into the lungs of the subject. A conventional scintillation camera or other radioactive recording device is operated to produce a permanent visual record. A separate air reservoir provides non-tagged air to fill the breathing passages and confine the radioactive tagged air to the lungs. The apparatus operates in sequence to supply the desired quantity of radioactive tagged air from a reservoir, followed by the measured quantity of ordinary air from a second reservoir, and then prevents exhalation during the time period necessary for the radioactive recording device to operate. The supply of premeasured quantities of tagged air and additional air insure that the subject will take only a normal size breath. Ganged stepping switches and a timing device provide automatic sequencing. A modified form of the apparatus utilizes a flexible wall radioactive gas reservoir and an associated pivoted lever which drops down to actuate a microswitch and open the valve to the additional air when the radioactive gas reservoir is depleted. A method is described in which measured quantities of tagged air and additional air are sequentially applied to the subject, exhalation is prevented during the period in which the radioactive recording is made, and exhalation is thereafter permitted.