Which term describes a substance that does not allow x-rays to pass and appears white or light gray on film?

Which term describes a substance that does not allow x-rays to pass and appears white or light gray on film?

• A. Radiolucent
• B. Radiopaque
• C. Maximum Permissible Dose (MPD)
• D. Automatic Processor

Answer: (B)

In radiography, how a substance interacts with X-rays determines how it appears on film. A substance that blocks X-rays strongly prevents them from reaching the film, so it shows up as white or light gray. This property is radiopacity. Materials with high density or high atomic numbers, like bone or metal implants, are radiopaque. The opposite concept is radiolucent, which means X-rays pass through more easily and the material appears darker on the image. The other terms listed are not about image appearance—one refers to radiation exposure limits, and the other to film development equipment. So the correct term is radiopaque.

In radiography, how a substance interacts with X-rays determines how it appears on film. A substance that blocks X-rays strongly prevents them from reaching the film, so it shows up as white or light gray. This property is radiopacity. Materials with high density or high atomic numbers, like bone or metal implants, are radiopaque. The opposite concept is radiolucent, which means X-rays pass through more easily and the material appears darker on the image. The other terms listed are not about image appearance—one refers to radiation exposure limits, and the other to film development equipment. So the correct term is radiopaque.