Radioactive energy is released from?

All REF: Vasudevan sree kumari 3/e p. 402, CSDT 10th e p. 1256 Rays used in radiotherapy/Radiodiagnosis are of two broad types as per linear energy transfer (LET) Low LET High LET x-rays a paicles y-rays Neutrons /3-rays Protons electrons Heavy ions