If an electron has enough energy, it will exhibit something called X-Ray Fluorescence (also known by its abbreviation XRF). This is when the x-ray causes an atom to become ionized and release its own x-rays, albeit at lower energy. Thus, the use of high powered x-rays can measure the strength and characteristics of building materials by measuring the resulting secondary x-ray energy. It's a very cheap alternative to measure the quantity of lead in paint and the quality of scrap metal.
Another thing about x-rays is that they can be used to see into things that are normally not visible. The calcium in bones will absorb x-rays differently than the surrounding tissue, so x-rays exposed through flesh against a photographic plate will reveal a glimpse of the bone structure - making the unseen visible.
But have you ever wondered what happens if you "x-ray" an image to see if there is anything hidden within? Now, there's a thought...
You can validate your puzzle solution with certitude.