Mutations are caused by DNA damage and genetic alterations that may occur spontaneously at a very low rate. The frequency of these mutations can be increased by using special agents called mutagens. Ionizing radiation was the first mutagen that efficiently and reproducibly induced mutations in a multicellular organism. Direct damage to the cell nucleus is believed to be responsible for both mutations and other radiation mediated genotoxic effects like chromosomal aberrations and lethality. Free radicals generated by irradiation of the cytoplasm are also believed to induce gene mutations even in the non-irradiated nucleus.

There are many kinds of radiations that can increase mutations. Radiation is often classified as ionizing or non-ionizing depending on whether ions are emitted in the penetrated tissues or not. X rays, gamma rays (&ggr;), beta particle radiation (), and alpha particle () radiation (also known as alpha rays) are ionizing form of radiation. On...