Thin layer CT refers to the selection of the CT reconstruction method to display images in thin layers, which means that the minimum thickness of the scanned layer is below 1mm. This situation is equivalent to the same as cutting a watermelon, when cutting very thinly it is not easy to miss the lesion and can detect nodules below 1mm. If you choose a thicker reconstruction layer, such as 7.5 mm, you may miss the lesion and some tiny nodules in the lung may not be easily detected. Therefore, it is better to choose a thin layer CT scan when scanning, which can clearly and completely display the lesions in the lung and not easily miss them.