|MadSci Network: Medicine|
Thank you for this ineresting question.
Xray pictures are essentially shadowgrams, generated when xray light interacts with photographic emulsion after passing through the object of study. Our bodies are partially translucent to xrays; soft tissues somewhat transparent, bones fairly opaque. Imagine a body made of semi-transparent gelatine with opaque bone to get a crude visible light analogy. The big difference is that xrays don't reflect or refract easily, so making xray images with lenses or mirrors does not work.
Colour photographs depend on the ability of our eyes to discern visible light of different wavelengths. Since xrays have wavelengths way to short for any any eye to see, they do not come in different colours as does visible light.
I hope this helps answer your question.
Emory Lawrence, MD
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