X-rays have shorter wavelength than visible light. But that's hardly the reason that they're used for medical imaging. xrays have much higher frequencies then visible light which means they have much greater penetrating ability. with xrays you can see inside the body. you can't do that with a visible flashlight no matter how bright and powerful it is.
The moon would be the size of a raspberry. It would be as far a like 4 or 5 inches. The sun would be as big as an cantaloupe.The sun would be as far as 10 or 11 inches.