Which materials can x rays pass through?

Answer 1

X rays are are able to penetrate less dense materials easily, such as muscle and skin tissue in medical situations or plastics and wood in other applications.

As the material becomes more dense, the x rays penetrate less easily.

Materials such as steel or bone in a medical setting are more dense along with such materials as lead and tungsten in engineering situations.

Answer 2

Simple answer: X-ray can pass all materials depending on the material layer thickness and the parameters of x-ray beam (energy and amount of photons).

In other words You can see through lead if the lead layer is thin enough.