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Humanity, constantly learning, growing, and facing more challenges each second

of the day. Whether the challenges are mental or purely physical. We have found more

efficient, safer, and easier ways of doing the tasks we may face. From moving cargo, to

sending information via the Internet. Probably the greatest accomplishments we have

made, are in the studies of medicine/treatment. And to be specific, the study of radiology.

Radiology, 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 then 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 it's self may have many forms. It could be a common radiograph, such as a chest x ray; a tomograph (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 include 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. And 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. A instrument called a transducer is used to transmit the sound waves and receive the echoes. The transducer must be in close contact with the skin, and a jelly like substance is used to improve the quality of the transmission.

And last of the diagnostic imaging tools is the MRI. MRI, which stands for Magnetic Resonance Imaging. Was a technique developed in the 1950's by Felix Bloch, and is the most versatile, powerful, and sensitive tool in use. The process of MRI was originally called NRI (Nuclear Resonance Imaging), but was found to be to confusing due to the fact that MRI's don't use radioactivity and ionizing radiation. The MRI generates a very powerful electromagnetic field, which allows the radiologist to generate thin-section images of any part of the body. Also it can take these images from any direction or angle, and is done without and surgical invasion. Another plus side to the MRI is The time it take to perform, where as a CAT scan may take 30-60 min. A MRI may only take 15 minutes max. The MRI also creates 'maps' of biochemical compounds within a cross-section of the body. These maps give basic biomedical and anatomical information that provides new knowledge and may allow early diagnosis of many diseases.

The MRI is possible in the human body because our bodies are filled with small biological 'magnets', the most abundant and responsive of these are the protons (in the nucleus of the hydrogen atom). The principal of the MRI, utilizes the random distribution of protons, which have basic magnetic properties. Once the patient is placed in the cylindrical magnet, the diagnosis process follows 3 steps. First, MRI creates a steady state of magnetism in the body, that is 30,000 time greater then that of the earth's own magnetic field. The rate of absorption in the body is measure in megahertz and gigahertz ranges. Then MRI stimulates the body with radio waves to change the steady-state orientation of the hydrogen protons. It then Stops the radio waves and 'listens' to the bodies electromagnetic transmissions at the selected frequency. The transmitted signal is used to create images much like those of the CAT scans, but are far more accurate and much easier to interpret.

In current practice, the MRI is preferred for diagnosing most diseases of the brain and central nervous system. And is the best diagnostic technique we know. It's images, information, and other vital information surpass that of its relatives the CAT scans, x rays, PET scans, etc. The MRI has yet another distinguishing feature it can determine between soft tissue in both normal and diseased states. The only



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