the difference is ingesting radioactive particles and getting a dose of radiation like an xray. when you get a small particle inside you, it releases radiation to locallised tissue for an extended period and cause the dna and cells to change aka cancer. you don't eat the radioactive particles when you stand in the sun so comparing the 2 is bs.
if you are saying its all ok, go enjoy a class of milk before bed time. it will heat itself.