The health of the lungs can be measured by a variety of tests, including pulmonary function tests (PFTs), chest X-rays, and CT scans. PFTs measure lung function by measuring the amount of air that can be inhaled and exhaled, and the rate at which it can be done. Chest X-rays and CT scans are used to detect any abnormalities or changes in the lungs, such as tumors or fluid buildup.