Fluoroscopic Pulmonary Densiography

A preliminary report is presented of fluoroscopic densiography as a method of pulmonary function study which approaches measurements of pulmonary ventilation over small areas of the lungs. After passage through the chest, the x-ray beam is transferred into electrical energy, modified and recorded on a strip chart. Fluoroscopic density is expressed as a percentage of the x-ray absorption. Respiratory fluctuation in an area is expressed as a percentage of the transmitted x-ray by the chest in that area. The fluctuation may be expressed as a percentage of the total fluctuation of one lung. The total fluctuation of one lung may be expressed as a percentage of the total of both lungs. These densities and fluctuations are altered in disease. Time relations between air flow at the mouth and the respiratory fluctuations show phase relationships varying from normals of zero to lags as high as 140 degrees in obstructive pulmonary emphysema and the opposite of lesser degree in bronchogenic carcinoma. This preliminary study suggests that fluoroscopic densiography may offer a valuable addition to pulmonary function studies in normal and disease states and may contribute diagnostic criteria.