FOR SEVERAL years various public health agencies have been carrying on mass chest x-ray surveys to ferret out persons with silent or incipient pulmonary tuberculosis in the campaign to eradicate this communicable disease. As expected, this search has brought to light many silent nontuberculous lesions, and the incidence has far exceeded anticipation. A significant number of these lesions are proving to be malignant tumors, discovered at a time when the prospect of cure by resection is most favorable. A larger number are benign tumors and other surgical lesions.
It should be pointed out that there exists in the chest a unique situation for the detection of silent disease. The air in the inflated lungs provides an excellent x-ray contrast medium, against which the abnormal tissue densities produced by disease are discernible before the lesions have advanced beyond a silent or incipient stage. Also certain lesions which are not directly visible