When we get the report of chest CT or X-ray, we are often confused by the “visible calcified shadow” and “visible streak-like shadow”. In fact, simply speaking, the doctor is trying to tell you that the shadow is not a tumor and there is no need to worry about it. But medical terminology cannot describe it like this. Let’s start with calcification. If you have been to Jiuzhaigou, you will find ancient pines in the water that are calcified, and the beautiful Huanglong is also formed by the hardening of calcium salt deposits. The same happens in human tissues when calcium salts harden. For example, it is a normal physiological process for a soft child’s bone to become a hard adult bone through calcification. However, when the body is sick, such as with tuberculosis, the lesion is healed through exudation, fibroplasia, and finally calcification. Of course, all kinds of tissues in the body can calcify, from joints, tendons, heart, pericardium to blood vessels, etc., but only the lungs are often X-rayed, and therefore such foci of calcification that are impervious to X-ray are often found. Then there are the fibrous striae. After septic infection of the skin, necrotic tissue is shed as pus and new granulation grows, eventually forming scars. When this happens in the lungs, this scar, which is much denser than normal alveoli, shows up as a fibrous streak shadow on x-ray. In the future, you won’t have to worry about this when you see calcifications or striated shadows again.