What is radiopaque?

• A. Darker areas on an image; fewer x-rays absorbed, more transmitted.
• B. Lighter areas on an image; more x-rays absorbed, fewer transmitted.
• C. Areas that are invisible on x-rays.
• D. Regions of air in the mouth.

Answer: (B)

Radiopaque describes how a material interacts with X-rays: it attenuates the beam more, so more X-rays are absorbed and fewer reach the detector, making that area appear lighter on the image. This is why radiopaque areas show up as light or white on radiographs—they block or absorb more of the X-ray beam. In contrast, substances that permit X-rays to pass with less absorption appear darker (radiolucent). The option stating lighter areas on the image due to more X-ray absorption and less transmission captures this behavior most accurately.