Radiology is the process of working and viewing inside the human body without breaking the skin. By using radiant energy, which may take the form of x-rays or other types of radiation, we are able to diagnose and treat many diseases and injuries. Both diagnostic and therapeutic radiology involve the use of ionizing radiation (Beta, Alpha, Gamma, and x-rays), with the exception of the MRI, which uses a magnetic field rather than radiation.
Radiology is classified as being either diagnostic or therapeutic. Diagnostic radiology is an evaluation of the body, by means of static or dynamic images or anatomy, physiology, and alterations caused by injury or disease. A majority of these pictures are formed by passing a low or high level of x-rays through the part of the body being examined, producing the static image on film. This image is called a radiograph or x-ray picture. The image itself may have many forms. It could be a common radiograph, such as a chest x-ray; a tomography, greek for "section", which is a radiograph obtained by timing the x-ray exposure to correspond with the movement of the x-ray tube and film in opposite directions around the plane of the body; or, finally, a computerized axial tomography (CAT or CT) scan. Which is a computer analysis of a sharply limited, thin x-ray beam passed circumferentially through an area of the body, giving the doctor of Technician a cross-sectional image; much like that of slicing a loaf of bread into sections.
Other images may be obtained by using ultrasound or MRI, or by recording the activity of isotopes internally administered and deposited in certain parts of our body. This practice is called nuclear radiology or nuclear medicine. This includes such techniques as a PET scan, or positron emission tomography, which uses patterns of the positron decaying to study metabolism reactions in the body. PET requires a cyclotron as an on-site source of short-lived, positron-emitting isotopes. The isotopes are injected into the patient along with a glucose related compound, and the positrons collide with the electrons in the body to produce photons. The photons are then tracked by a tomographic scintillation counter, and the information is processed by a computer to provide both image and data on blood flow and metabolic processes within bodily tissues. PET scans are particularly useful for diagnosing brain tumor and the effects of strokes on the brain, along with various mental illnesses. They are also used in brain research and in mapping of brain functions.
Another form of imaging is ultrasound. Ultrasound, which uses very high frequency sound, is directed into the body. And because the tissue interference?s reflect sound, doctors are able to produce, by use of a computer, a photograph or moving image on a television. Ultrasound has many application uses on the body, but is more commonly used in examinations of the fetus during pregnancy, because use of radiation may affect the outcome of the baby. Some other practices for ultrasound include examination of the arteries, heart, pancreas, urinary system, ovaries, brain, and spinal cord. And because sound travels well through fluids it is a very useful technique for diagnosing cysts, which are filled with fluid, and fluid filled structures such as the bladder. Since sound is absorbed by air and bone it is impossible to use a ultrasound on bones or lungs.
The sound waves are produced by a random oscillating crystal, and are inaudible to humans. An instrument called a transducer is used...