X-rays are a form of high frequency, high energy electromagnetic radiation which since their discovery in 1895, have been used increasingly in medicine both for diagnosis and treatment (Bruland, 2007). Wavelength for x-rays is from about 10-8m to about 10-11m or from less than a billionth of an inch to less than a trillionth of an inch. The corresponding frequency range is from about 3x1016HZ to about 3x1019HZ. (1HZ = ICPS). X-rays can be used to produce images of bones, organs and internal tissues. Low doses of x-rays are passed through the tissue and cast images-essentially shadows on to film or onto a florescent screen (Lam, 2007).
x-rays have the potential to damage living cells, especially those that are dividing rapidly. Because cancer cells divide rapidly, high doses of x-rays are used for treating cancer. Each of the body’s tissues absorbs x-rays in a predictable way. Bones, which are dense and contain calcium absorbs x-rays well (Connell, 2009).
In contrast, soft tissues – skin, fat tissue, blood and muscle, absorb x-rays to a lesser extent. Thus when an arm is placed in the path of an x-ray beam, the x-rays pass readily through the soft tissues but penetrate the bones much less easily. As a result, the arm casts a shadow on to film or on a fluorescent screen with the bone appearing white and the tissues dark gray.
(Veldeman 2008) says that hollow or fluid filled parts of the body often do not show up well on x-ray film unless they first have a contrast medium introduce into them. X-rays can be used to obtain an image of “slice”. Through an organ or part of the body by a technique known as tomography. More detailed and accurate images of a body slice are produced by combining tomography with the capabilities of a computer to give computed tomography scanning (CT or CAT scanning).
X-rays are produced in a highly evacuated glass bulb called an x-ray tube that contains essentially two electrodes-an anode made of platinum, tungsten or another heavy metal of high melting point and a cathode. The fast moving electrons is allowed to bombard metals, the fast moving electrons knock electrons out of the inner shells of the metal atoms. The dislodged electrons are replaced by electrons moving in from the outer shells. Thus movement of electron is accompanied by the omission of x-ray (Ababio, 2003).
X-rays can penetrate easily through most solid substances which are opaque to visible light such as metal foils, flesh, wood and paper.
When electron hits the target, x-rays are created by two different atomic processes: