A large sample study abroad found that the detection rate of lung nodules by LDCT was 24.2%, that is, at least one person in five people could detect lung nodules, while other studies were even higher, up to 40%. The detection rate of nodules on chest radiograph is much lower. The detection rate of pulmonary nodules on ordinary X-ray chest films is about 0.09%-0.20%. Why is this?
It is well understood that CT is a tomography technology, which can look at the lung layer by layer. The thickness of the scanning layer is very thin, about 1mm, so you can see small nodules of several millimeters, which will not be blocked by bones or other tissues. Chest radiographs compress lung, bone, heart, mediastinum and other tissues into one piece, so small nodules are easy to be missed, especially in some special positions, such as behind ribs and mediastinum. Or some ground glass nodules are more likely to be missed.
Is lung nodule lung cancer detected by physical examination?
No, 96.4% of pulmonary nodules detected by LDCT are benign; 94.5% of the pulmonary nodules detected by chest X-ray were benign. Diameter ≤5 mm: malignant rate <1%; Diameter 5 ~10 mm: 6% ~ 28%; Diameter > 20 mm: 64% ~ 82%. As for how to judge whether the nodule is lung cancer? Size, shape and density analysis, further inspection and subsequent review involve too much professional knowledge. In short, listen to the radiologist's advice on how to deal with it.