Cosmic radiation is mainly protons and heavier nuclei. It's called radiation for legacy reasons, but it's a different beast from Earth's medical CT scans and X-

Cosmic radiation is mainly protons and heavier nuclei. It's called radiation for legacy reasons, but it's a different beast from Earth's medical CT scans and X-rays which are manly photons. Cosmic radiation hitting planes is also not the original cosmic protons and He nucleus etc, but secondary N and O nucleus hit by Cosmic particles creating a shower of neutrons, secondary and gamma protons, muons, pions, nuclear fragments... There's also a high dose of photons from these collisions, but proportionally it can be 500x less photons than a CT scan for a 10h USA-Europe flight. What's biologically significant for air crew are these secondary protons and neutrons, which punch above their weight in damage interactions, they are not comparable to X-rays in Sieve alone.