The main aim of radiation therapy is used to reduce the cancer pain which is caused by a variety of factors. Alpha, beta, and gamma radiations these are the three types of radiation are used to killing the cancer cell. The exact mechanism of pain relief through radiation therapy is not known. In case of metastatic bone pain management if there are multiple bony lesions causing pain at multiple sites, then hemibody external RT is given. Oral or IV administration of isotope therapy is an alternative to hemibody radiation. The mechanism action of isotope therapy is to localize around the metastatic sites and selectively deliver radiation to all metastatic sites simultaneously. The external RT relieves hepatic pain, the isotope tagged targeted therapy is gaining acceptance. The severe headache due to the compressive effect of brain tumor can be relieved through external RT. peripheral nerve producing severe pain and it involved the growth of a tumor. Brachytherapy are sealed radiation sources which in the form of pellet. The beta rays kill tumor cells resulting in tumor reduction and alleviation of a pain.