Ground glass nodule foci become lighter in density is a sign of improvement. Milled glass nodule is an imaging concept, refers to the thin layer CT shows the density of cloudy material in the lung nodules, clinically most asymptomatic, and slow-growing, imaging according to the density of two categories, simple milled glass nodules and mixed milled glass nodules. Milled glass nodules may be caused by lung tumors, inflammation or specific infections. If the density of the milled glass nodule foci becomes lighter after treatment, it may be an inflammation of the lungs, with dissipation, absorption, and improvement. If the density of the milled glass nodule foci is less than 6mm, you can make a follow up plan with the help of your doctor, and review the milled glass nodules regularly. If there are other symptoms, go to the hospital in time to prevent delay.