I was reading How Do Sodium Iodide (Scintillation) Detectors Work?

https://www.ntanet.net/how-do-sodium-iodide-scintillation-detectors-work

To quote ”The basic principle is the same for every scintillation-type detector: when radiation strikes the scintillator it causes it to give off photons of visible light (that’s the scintillation part).”

When radiation strikes the scintillator it does not cause it to give off photons of visible light. I think what is happening is that the radiation (which is an electromagnetic wave) is changed (ie. it’s wave is either compressed or elongated by the crystal) into a visible spectrum wave ie light.