Pulmonary nodules refer to foci in the lung that are round or circular in diameter and do not exceed 3 cm, more than 3 cm is called an intrapulmonary mass, the nodule boundary is relatively clear, according to the density is divided into ground glass nodules, mixed nodules, solid nodules, taking beaten eggs as an example, ground glass nodules only have egg white, no egg yolk, through the egg white can be seen at the bottom of the disk pattern, indicating that there is a certain transparency of the nodule. The mixed nodules show transparent egg white around the nodules and mixed material in the middle; the solid nodules only have egg yolk and no egg white, and the pattern at the bottom of the plate cannot be observed through the egg yolk.