How x-rays damage

[O]n a fundamental level, x-rays damage atoms from the inside out: They typically kick out deeply bound electrons, punching a “core hole” into the atom. This unstable situation unleashes a cascade of electronic relaxation events that turn neutral atoms into ions, thus breaking chemical bonds in molecules or creating defects in solids. — Thomas Pfeifer, Science Magazine Vol. 369, Issue 6511, pp. 1568–1569

The end.