Measurement of Absolute Lung Density by Compton-Scatter Densitometry

The non-invasive determination of absolute lung density would be of great importance if it could be used in the evaluation of patients with pulmonary edema. To obtain this measurement, we have developed a a portable densitometer using CdTe room-temperature detectors, compact collimators made of tantalum tubes and a Gd-153 source. System response in the density range of 0.1 to 1 g/cm3 is linear. Variations in the absorption paths of up to 8 cm of lucite do not produce significant changes on measured density values.