Question: Respected sir, i have heard that neutrinos have almost no interaction with matter . Can these take place of X-rays in medical sciences as these will be more safe?

Jack Miller answered on 19 Jun 2013:

Hi Arshdeep,

Great question! You’re right in that neutrinos don’t interact with matter very much — so little, in fact, that if you wanted to use a piece of lead to stop a neutrino, well, you’d probably need more lead than we have in our solar system. In fact, a neutrino of moderate energy could easily penetrate a thousand light-years(!) of lead. Actually detecting neutrinos is a huge challenge — involving simply vast numbers of neutrinos being fired at detectors the size of mines buried underground.

I can tell that the reason you think neutrinos might be a better thing to use is because X-rays interact quite a lot with the body, and can cause damage that might lead to cancer. Neutrinos definitely wouldn’t interact with your body at all — there are billions of them passing through you at the moment! This wouldn’t make for very good images at all. What you really want an imaging technology to do is interact with your body — so you can measure stuff about it — but not cause any damage. It turns out that MRI and ultrasound are the best ways of doing this at the moment, involving relatively intense but low-energy waves to probe what’s going on.

Hope this helps!

— Jack