Why do muscle appears black on x-ray?

Muscle appears black on an x-ray because it is less dense than bone. X-rays are a form of electromagnetic radiation, and the amount of radiation absorbed by an object depends on its density. Denser objects, such as bone, absorb more radiation and appear white on an x-ray, while less dense objects, such as muscle, absorb less radiation and appear black. The density of muscle is also affected by its water content. Muscle that is dehydrated is less dense and appears blacker on an x-ray, while muscle that is well-hydrated is more dense and appears whiter.