Fluoroscopic pulmonary densiography.

Abstract

Kourilsky and MarchaP presented papers at the Fourth International Congress on Disease of the Chest which stated an accuracy of 90 and 95 per cent in the diagnosis of bronchogenic carcinoma by their technique of fluoroscopic densiography. They have also reported on the use of their methods as a means of differential pulmonary function study.2 This study was undertaken because their methods appeared to offer promise of recognition of localized pulmonary disease and areas of localized dysfunction. Method A photomultiplier tube with a sodium iodide crystal is exposed to the fluoroscopic beam after passage through the chest by means of an orifice 3/32 inch in diameter and 1/8 inch long. The system is centered on the x-ray tube and mounted on the patient side of the fluoroscopic screen. The output of the tube is filtered, the impedances matched, and recorded photographically by a mirror galvanometer. Improvements in the circuitry are being made so that presentation of details will be made at an appropriate stage in the work (Fig. 1). The direct current output is measured by a damped vacuum tube voltmeter both with and without the patient. The fluoroscopic density is the percentage drop in voltage between the output with and without the patient. The variation in the output is recorded as an indication of the volume change of the chest due to respiration. The fluoroscope is adjusted to 80 kilovolts and 1.5 milliamperes which delivers 1.5 roentgens per minute at the table top.