It would seem that X-rays have been studied and described so fully that something new, interesting, all the more mysterious is out of the question. But, oddly enough, they are still mysterious invisibles, although they have been investigated since 1895. In the world of stars and atoms, cells and organisms - everywhere there is a place for searches designed to solve questions, or even puzzling equations with many unknowns related to X-ray radiation. This is the leitmotif of the book of the doctor of medical sciences P. Vlasov.