Radiology is one of the modern science, just over a100 year and a specific since November 1895 when the physicist William Rontjn conduct some tests on the elevator and the landing pad during the experiments and he noted the presence of flash on the sensitive paper used for testing. Since that time, he began to think of something in unknown places and others were visible by X-X-RAY. Then he repeated the test many times and after eight weeks only, and specifically in 28/12/1895 he obtained on the first X-ray image of his wife’s hand on sensitive paper. Since it began, with his Group other researches focused on the physics of radiation and published research in March 1896 and May 1897. (Electromagnetic waves which have the characteristics of waves in terms of wavelength, speed, and the reluctance speed = frequency x wavelength )
These productions are of the effort there is a difference between the elevator and the landing pad in the vicious circle of tubes known as the air-tube X-ray and beyond in the form of cone-shaped package and then deployed in the circumference as directed waves.
After that, they discovered (booster panels) were that converted X rays
 to a light flash is more effective in the sensitive film, which receive the radiation. Continued scientific research and tested with known mediator of radio opaque materials are those that provide hardware and black members have been known as contrast media. Hence, the word began to circulate-radiations has become so much aware of radiation medicine taught in the medical schools starting in 1907. The events came one after another and used X-ray diagnostic imaging in America's war against Spain in 1906 where he was filming the bone and lead. Time known a priori that the human body contains three essential components: bone, soft tissue, and the air. The bones Weaken radiation waves and prevent it from reaching the sensitive and therefore is called "dark radiation”. Also soft tissue are weaken some of the frequencies of X ray and implemented some of the other waves of radiation that sensitive to the film and therefore called "dark half of the rays, but the air is not weakening the   radiation waves and implemented through the sensitive film  therefore called " non-polarized X-ray. "
We have a variety of materials for X-ray dark "dark mediator" for specialized organs of the body and each for the purpose of diagnosis, such as, for example:
Mediator of the dark digestive system (barium -gastrografin).
Dark median urinary system (mediator dark blood in the water soluble substance such as (iopamiro).
Circulatory system and blood vessels (an intermediate dark blood in the water soluble substance such as omnipaque).
The spinal cord and brain (intermediate opaque non-ionic melts in water, such as the article omnipaque ).
Lung and bronchial (dark intermediary such as an article hetrastate).
Uterine cavity and fallopian channels (mediator dark oily substance such as libidol).
Following the rapid development of the evolution of species-ray booster panels, as well as appropriate for the different catheter blood vessels. This was followed by successive use of film and movies, and especially for imaging the heart and blood vessels. In the late fifties login theoretical radiology examination “fluoroscopy" and then 2D dimensions is a real revolution in radiology.
Although the radiology considered as a modern ,develop knowledge  , however, it was enormous and served as a useful diagnostic medical revolutions of mankind and often helped in the diagnosis of unknown diseases, including:
Establishing of  CT scan ( computed tomography ) late seventies and early eighties.
Establishing of new imaging Methods, including radioactive isotopes such as imaging, "nuclear medicine", including non-radiological imaging such as (ultrasound) late seventies and magnetic resonance imaging (MRI) late eighties. The three are serving as last three revolutions in the Radiology (3D-CT), (ultrasound  Doppler), (MRI).
The ultrasound and MRI are not radioactive in nature, devoid of any damage to radiation exposure took place and therefore a rapid pace to reduce the use of X-ray imaging techniques and thus the radiation damage.
Although the X-ray is difficult to restrict them to many benefits, however, at the same time there is some damage was justified and unjustified, and divided the damages caused by medical radiation, as follows:
The type of radiation - a diagnostic or therapeutic.
The amount of radiation - radiation dose.
Place of exposure (type of TISSUE that exposed to radiation). The age of the patient exposed to to radiation.
In the area of diagnostic irradiation prevents outright prevent the fetus in its mother's womb, and especially during the first pregnancy, and then being allowed in very limited periods of pregnancy in the last, if necessary (the mother's life) to determine the type of the disease and then treatment. And after birth we advised to reduce exposure to radiation as children across the cells in the process of growth and possibly affected by radiation significantly. In adults, there are adult cells and tissues more sensitive to radiation than others, including: cells of the testes and ovaries, cells of the breast, red bone marrow in the ribs and the ends of bones and long bones, cells, and especially the eyes and lens of the eye cornea.
The danger of radiation exposure is to stop the growth of cells or changes in cytoplasma within cells and are dangerous here, where these cells are vulnerable to random growth that called cancers. To avoid such risks are special techniques to protect patients and workers from the dangers of radiation parameters such as the use of lead shields and protective measures and personal dose(TLD).