十万个为什么·科学启蒙30篇（4）

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为什么X光能穿透软组织成像

X-rays are high-energy electromagnetic waves that can pass through many materials.
Soft tissues like muscle and fat absorb only a small portion of these rays.
Denser materials such as bones and teeth absorb much more X-ray energy.
A detector behind the body captures how many X-rays make it through each area.
Areas where more rays pass through appear darker on the final image, like soft tissue.
Regions where fewer rays get through—like bone—show up as bright white patches.
This contrast lets doctors spot fractures, tumors, or other hidden structures clearly.
Modern digital X-ray machines adjust exposure to minimize radiation dose safely.
Lead aprons protect unaffected body parts because lead absorbs X-rays completely.
The whole process relies on differences in material density—not color or light.