What Happens If You X-Ray Metal?

Metal appears as a bright area on an X-ray, blocking visibility of underlying structures. The reason you're asked to remove metal is to give the radiologist an unobstructed view of the area of interest. Basically, you remove metal because it blocks anatomy. If you have a metal implant, obviously you can't remove it for an X-ray. If the technician is aware of it, he may position you differently to get the best imaging results or take X-rays from multiple angles.

The reason metal appears bright on the X-ray image is that it is extremely dense, so X-radiation does not penetrate it as well as it does soft tissues. This is also why bones appear bright on an X-ray. Bones are denser than blood, cartilage, or soft organs.

Unless the metal item is directly in the path between the X-ray collimator and the image receptor, there's no issue with having metal objects in the same room as an X-ray machine. On the other hand, metal objects are not permitted in a room housing MRI equipment because the objects will be drawn toward the powerful magnets when the machine is turned on. Then, the problem isn't with the image; it's with the items, which could become hazardous projectiles, possibly injuring people or damaging equipment.