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Archived Articles about Health and Medical
Soy May Not Help With Hot Flashes By: Dr. Victor Marchione
Soy supplements may not be good for helping to maintain bone or relieving menopausal symptoms, according to a recent study.(read entire article)(posted on: 2011-08-15)
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Omega-3s Vs. Depression, Part 2 By: Dr. Victor Marchione
Can eating considerable amounts of fatty fish help protect you from depression? When you look at the facts, the picture becomes clearer. And it's pretty good news.(read entire article)(posted on: 2011-08-15)
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Strength Training For A Better You By: Samantha Dale
Strength Training for a Better You(read entire article)(posted on: 2011-08-15)
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Selecting The Child Care Hospital For Mother And Child By: Cadman
The word “hospital” looks a little alarming, and more so ever for a child. Environ of the hospital can be a little scary, with different patients carrying different diseases and with not so friendly atmosphere.(read entire article)(posted on: 2011-08-15)
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Four Tips To Be Certain You Are Using Your Lifepak 1000 Defibrillator In The Proper Way By: Andrew Bui
This defibrillator, the LIFEPAK 1000 is built to be an easy tool to use to save lives, however it is usually helpful to understand as much about this type of tool, before you use it.(read entire article)(posted on: 2011-08-15)
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Ehr Meaningful Use Increases Accuracy And Efficiency By: Andrew Bui
Environmentalists love EHR Meaningful Use because it saves massive amounts of paper and prevents many forests from having to be sacrificed.(read entire article)(posted on: 2011-08-15)
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The Most Commonly Used Methods To Disinfect Fruits By: Emma111
As we all know, fruits are the good foods to keep healthy and beautiful. The fruits purchased in the market are often good in appearance, but the surface peels are often stained with dust, pesticides and bacteria; if people do not clean and disinfect fruits to eat, it is easier to lead to diseases. In general, there are several methods that are most commonly used in cleaning and disinfection. They are as follows:(read entire article)(posted on: 2011-08-15)
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Physical Therapist Job Satisfaction Ratios (are They Really As Good As You Imagine?) By: Johnnie Irwin
Physical therapy is a distinctive occupation for several different reasons, but one reason stands above all others. It is in reality one of the highest rating occupations in terms of job satisfaction from actual people within the profession. This really is phenomenal, as it shows that these individuals don't merely like what they do, but also get compensated for doing it in a variety of different ways. Find out more about the career satisfaction associated with physical therapists on this page.(read entire article)(posted on: 2011-08-15)
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X-ray Equipment From A-z By: Linday Miller
The Evolution of X-Ray
The electromagnetic nature of x-rays became plain when it was found that crystals bent their path in the same way as gratings bent visible light: the orderly rows of atoms in the crystal acted like the grooves of a grating. X-rays are able to penetrate some depth of matter. Medical x-rays are produced by letting a stream of fast electrons come to a sudden stop at a metal plate. It is believed that X-rays emitted by the sun or stars also come from fast electrons.
The images produced by X-rays are due to the different absorption rates of different tissues. Calcium in bones absorbs X-rays the most, so bones look white on a film recording of the X-ray image, which is called a radiograph. Fat and other soft tissues absorb less, and look gray. Air absorbs the least, so lungs look black on a radiograph.
Wilhelm Conrad Röntgen discovered an image cast from his cathode ray generator, projected far beyond possible range of the cathode rays. Further investigation showed that the rays were generated at the point of contact of the cathode ray beam on the interior of the vacuum tube, that they were not deflected by magnetic fields, and they penetrated many kinds of matter.
A week after his discovery, in 1895, Rontgen took an X-ray photograph of his wife's hand which clearly revealed her wedding ring and her bones. The photograph electrified the general public and aroused great scientific interest in the new form of radiation. Röntgen named the new form of radiation "X-radiation", therefore the term X-rays.
What is X-Ray?
X-rays are waves of electromagnetic energy. They behave in much the same way as light rays, but at much shorter wavelengths. When directed at a target, X-rays can often pass through the substance uninterrupted, especially when it is of low density. Higher density targets (like the human body) will reflect or absorb the X-rays. They do this because there is less space between the atoms for the short waves to pass through. Thus, an X-ray image shows dark areas where the rays traveled completely through the target (such as with flesh). It shows light areas where the rays were blocked by dense material (such as bone).
X-Ray Applications
The most important application of the X-ray has been its use in medicine. This importance was recognized almost immediately after Roentgen's findings were published in 1895. Within weeks of its first demonstration, an X-ray machine was used in America to diagnose bone fractures.
Thomas Alva Edison invented an X-ray fluoroscope in 1896. American physiologist Walter Cannon used Edison's device to observe the movement of barium sulfate through the digestive system of animals and eventually, humans. In 1913, the first X-ray tube designed specifically for medical purpose was developed by American chemist William Coolidge. X-rays have since become the most reliable method for diagnosing internal problems.
What an X-Ray Tube is Comprised of
Inside the X-ray tube, as with any electronic vacuum tube, there is a cathode, which emits electrons into the vacuum and an anode to collect the electrons, thus establishing a flow of electrical current, knows as the beam, through the tube. A high voltage power source, 30 to 150 kilovolts (kV), is connected across cathode and anode to accelerate the electrons. The X-ray spectrum depends on the anode material and the accelerating voltage.
In many applications, the current flow, in the range 1mA to 1A, is able to be pulsed on for between about 1ms to 1s. This enables consistent doses of X-rays, and taking snapshots of motion.
Electrons from the cathode collide with the anode material, usually tungsten, molybdenum or copper, and accelerate other electrons, ions and nuclei within the anode material. About 1% of the energy generated is emitted/radiated, usually perpendicular to the path of the electron beam, as X-rays. The rest of the energy is released as heat. Over time, tungsten will be deposited from the target onto the interior surface of the tube, including the glass surface.
Eventually, the tungsten deposit may become sufficiently conductive that at high enough voltages, arcing occurs. The arc will jump from the cathode to the tungsten deposit, and then to the anode. This arcing causes an effect called "crazing" on the interior glass of the X-ray window. As time goes on, the tube becomes unstable even at lower voltages, and must be replaced. At this point, the tube assembly is removed from the X-ray system, and replaced with a new tube assembly. The old tube assembly is shipped to a company that reloads it with a new X-ray tube.
The range of photonic energies emitted by the system can be adjusted by changing the applied voltage, and installing aluminum filters of varying thicknesses. Aluminum filters are installed in the path of the X-ray beam to remove "soft" radiation. The number of emitted X-ray photons, or doses, is adjusted by controlling the current flow and exposure time.
Rotating Anode System
To avoid the order heating of a fixed point on the anode surface, a rotating anode system was introduced. The anode can then be rotated by electromagnetic induction from a series of stator windings outside the evacuated tube. Because the entire anode assembly has to be contained within the evacuated tube, heat removal is a serious problem, further exacerbated by the higher power rating available. Direct cooling by conduction or convection, as in the cooling tube, is difficult. In most tubes, the anode is suspended on ball bearings with silver powder lubrication which provide almost negligible cooling by conduction. A recent development has been liquid gallium lubricated fluid dynamic bearings which can withstand very high temperatures without contaminating the tube vacuum. The large bearing contact surface and metal lubricant provide an effective method for conduction of heat from the anode.
The anode must be constructed of high temperature materials. The focal spot temperature can reach 2,500 ºC during an exposure, and the anode assembly can reach 1,000 ºC following a series of large exposures. Typical materials are a tungsten-rhenium target on a molybdenum core, with graphite. The rhenium makes the tungsten more ductile and resistant to wear from the impact of the electron beams. The molybdenum conducts heat from the target. The graphite provides thermal storage for the anode, and minimizes the rotating mass of the anode.
Current High-Performance X-Ray Tubes
Increasing demand for high-performance computed tomography scanning and angiography systems has driven development of very high performance medical X-ray tubes. In these X-ray tubes power dissipation can be up to several KW'S.
MedWOW: An Excellent Source for X-Ray Tubes
MedWOW features X-Ray tubes from all of the major manufacturers including: Dunlee, Fischer Imaging, GE Healthcare, Philips, Picker, Raymed, Shimadzu, Siemens and Varian, with more being added all the time, so finding exactly what you need is efficient and simple for busy medical professionals. With dozens of types of x-ray tubes currently featured through MedWOW's comprehensive online catalogue ─ locating and buying your next x-ray tube is trouble- free and as thousands of medical professionals use the MedWOW portal on a daily basis, the prices are always competitive.(read entire article)(posted on: 2011-08-15)
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How To Prevent Heat Stroke In Summer By: tanya
Everybody knows that extreme heat can make us sick. People are dying from heat….there are thousands and thousands of people each day fighting against heat stroke.(read entire article)(posted on: 2011-08-15)
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