Most babies are able to begin sitting up when they reach the age of 4 months. However, some of them might need more time and start sitting independently when they become 7 months old. Until this time, the baby would definitely have learned how to roll and would be able to hold his head up too.
UV radiation, in the form of lasers, lamps, or a combination of these devices and topical medications that increase UV sensitivity, are sometimes used to treat patients with certain diseases who have not responded to other methods of therapy.
X-rays, gamma rays and beta particles are all used in medicine to treat internal organs. X-rays are produced by firing electrons at a metal target and gamma rays are emitted by the nucleus of radioactive atoms. Gamma rays are used to kill cancer cells, to sterilise medical equipment and in radioactive tracers.