The body (at least, the fleshy parts) isn't terribly opaque to X-ray wavelength light -- the point being that opacity depends on wavelength. If you've got a (w

The body (at least, the fleshy parts) isn't terribly opaque to X-ray wavelength light -- the point being that opacity depends on wavelength. If you've got a (white) flashlight handy, you can stick your fingertip in front of the front element. A healthy amount of red light will come through. Flesh, as it happens, is also relatively transparent to strong red light... just not as transparent as to x-rays.