For small lung nodules: (a common problem for many patients with lung nodules) 1, for mm level nodules, there are errors in measurement by different hospitals and doctors. The doctor’s measurement is a visual judgment of the edges. 2, morphological changes and your degree of inspiration and breath-holding each examination also have a relationship. Density measurement is even more error, only as a reference. 3, density changes are mainly for the grinding glass nodules, for solid nodules is not significant. 4, once every six months or once a year is enough to monitor the nodules. Review recommendations, the general equipment or conventional dose CT is better, low-dose high requirements for equipment. Low-dose CT is noisy and can detect nodules, but without the appropriate post-processing techniques, the details are slightly worse. If anxiety, you can also review once every six months. 5, the measurement error of CT value and size of tiny nodules will be large, do not be nervous first. Routine annual follow-up is enough.