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 are a form of electromagnetic energy just light-rays and micro-waves are. X-rays have more energy than light-rays so they can penetrate and travel through materials that light-rays cannot. Film is sensitive to x-rays in the same way that it is to light-rays, so X-rays can be used produce images. X-rays that are sent through an object can produce an image on a piece of film placed on the opposite side of the object.