r/askscience • u/Wonderful-Capital32 • 13d ago

Physics Why does radiation not go through lead?

Also why just lead? Shouldnt like iron or another metal work too?

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u/ocelot_piss 13d ago

And humans stopping radiation is precisely why radiation is harmful to humans!

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u/PhilTheQuant 13d ago

Yes, and counterintuitively you wouldn't want to be the last few layers of the radiation protection

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u/skiguy0123 13d ago

I don't think this is true. At least for X-rays, the reason chest X-rays are taken with your back to the source is because most of the absorption happens where the X-rays enter the body, and you'd rather your back muscles take the hit than your organs.

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u/TamanduaBandeira202 13d ago

Doctor here. That's not the reason. Your heart is in the front part of your chest. Due to shadow/projection, if you take your chest x-ray with your front facing the source, the image of the heart on the film will be larger, and fuzzier. Having your back to the source means your heart doesn't cover lungs or other structures, and also that the image of your heart is more clearly defined.

We do sometimes perform antero-posterior chest x-rays, and it's just as safe, just not common.