Radiodensity
（重定向自Radiopacity）
Radiodensity (or radiopacity) refers to the relative inability of electromagnetic radiation, particularly X-rays, to pass through a particular material. Radiolucency indicates greater transparency or "transradiancy" to X-ray photons. Materials that inhibit the passage of electromagnetic radiation are called radiodense or radiopaque, while those that allow radiation to pass more freely are referred to as radiolucent. The term refers to the relatively opaque white appearance of dense materials or substances on radiographic imaging studies, compared with the relatively darker appearance of less dense materials.