I'm looking at why bone shows up white on a radiograph.
The only explanation I seem to get is the bone is dense and 'absorbs more x-rays'. This is all ok, but it still doesn't seem to explain why the bone appears white on the final image.
I'm wondering if the intensity received on the screen maps onto a greyscale image, showing less intense places as white by choice or if there is anything physical going on?
Best Answer
It's because they're showing you the negative film. The film starts as clear, and turns darker the more light it is exposed to. Because that became the convention in the days when film was all there was, we stick with it. So, you're seeing the shadow from the denser bone as white because it's a negative.
Edit: Saying "That's all they had" probably isn't quite right. We've been able to produce prints from negatives for a very long time - longer than we knew about x-rays. More likely, it saved costs to work with negatives (both time and materials), and working directly with the negative is a higher fidelity image than any print made from the negative.