Radiotherapy is an integral part of oncotherapy, usually used in combination with surgical therapy and/or chemotherapy in order to enhance the overall effect. Anti-cancer drugs have been continuously developed parallel with the widening of our molecular understanding of cancer biology. The substitution of current conventional agents used in everyday practice to modern radio enhancers is one of the main objectives is clinical oncology. At the present time these newer radiosensitisers such as metal-oxide nanoparticles, compounds with wide cross-section for neutron capture, hypothetical hybrid particles and gadolinium-based agents are being used particularly in preclinical or early-clinical studies.