1. The difference between electromagnetic and sound waves.
The difference between sound waves and electromagnetic waves in basically caused by their nature. Sound waves can be formed by the any sources that oscillates in elastic environment ( the frequency of the sound waves lies in the range between 20 Hz and 20000 Hz) , while electromagnetic can be only formed by oscillating electric charges. As it’s known from physics alternating electric field ( a kind of matter that exists around electric charges) also creates a magnetic field that also acquires to be alternating.
So if to stimulate with a help of oscillating electric charges alternating electromagnetic field, then in the surrounding space appears the order of mutual transformations of electric and magnetic fields, spreading form a point to point. This will be a periodical process in space and time and it’ll be considered to be a wave, an electromagnetic wave.

2. Electromagnetic spectrum and its members. Common properties of electromagnetic waves.

Electromagnetic waves can be grouped by their wavelengths or their frequencies (as one is inverse of another). The complete range of electromagnetic waves is called the electromagnetic spectrum or (EM). Basically electromagnetic wavers are divided into radiowaves, microwaves, infrared, visible light, ultraviolet, X-rays and Y-rays(gamma rays).

Frequency Wavelength

The spreading of the electromagnetic waves is also accompanied with transferring of energy and impulse.

Ultrasound.
Ultrasound are elastic waves with a frequency Hz . High frequency and short wavelength give the opportunity of directed spreading of ultrasound waves as well generation of high mechanical energies with a help of powerful ultrasound waves that has got a wide spreading in modern technology and medicine.
Ultrasound effect was discovered in 1880 by Curie brothers. They discovered that if to cause a pressure on the crystal of quartz, then on it’s sides there’ll appear electric charges. Now this property called piezoelectric effect is widely used in order to discover ultrasound. By shrinking and expanding the crystal generates alternating current, and vise verse if connect a crystal with the source of alternating current , it will generate ultrasound waves. Modern ultrasound generators are based on this technique.
Ultrasound had found a great spreading and usage in modern medicine both in diagnostics and treatment.
Diagnostics and ultrasound.
Ultrasound is used in the diagnostics of the following medical related issues: obstetrics and gynecology, cardiology and cancer detection. Themain advantage of ultrasound vs. Using x-rays that it doesn’t has dangerous radition and is done faster then X-rays examination. Here are the areas of using ultrasound in medicine:
Obstetrics and Gynecology :
Fetus size measuring, in order to determine due date Determination of the fetus position
Checking planceta’s position in order to see if there any abnormal deflexions
Determining the fetuses nuber in the uterus
Gender checking of the fetus
Checking the baby’ss growth rate, but periodical examinations
Checking if tthere are any life-threatening issues caused by pregnancy
Detecting the aount of amniotic fluid that curshes the fetus
Checking for tumors of the ovary and breast
Cardiology :
Checking the inside of the heart to determine if there any abnormal structures or functions
Determining and measuring blood flow through the heart and main blood vessels
Urology:
determining blood flow through the kidneis
checking for kidney stones
checking for early cases of prostata cancer

Ultrasound machine with various transducer probes

An ultrasound machine that is used for diagnostics consists of the following parts:
transducer probe – probe used for sending and receiving of the sound waves
central processing unit (CPU) -a computer that does needed calculations and makes the visible image of the subject of examination, connects to transducer trube and has power supplies,
transducer pulse controls – controls the frequency and amplitude of waves used for diagnostics
display – displays the image from the ultrasound data modeled and calculated by the CPU
keyboard/cursor – for inputting data and managing the process related to using the CPU
disk storage device (hard, floppy, CD) – stores got images and images related data
printer – used for printing images from the monitor. The function sof the major parts are quite clear so it’s important to identify the functions only of the transducer tube, which is the essential part of ultrasound machine.It’s functions are to make and recieve echoes.By the waves used the whole process of CPU and transducer tube allows to determine the fields of view of the examination subject,it’s shape, to determine how deep the sound waves penetrate and the resolution of the image. The transducer tube generates the waves, which are reflceted form the subject of the examination, then by comparing the waves sent and recieved the CPU models the image of the examuination subject which is then displayed on the monitor.
Ultrasound therapy
The regimes of ultrasound energy can be both continious and impulsive. In the regime of conttinuity ultrasound stream is directed on the body’s tissues. In impulsive regime the sending of energy is changing with pauses, with different tim eof both.
Ultrasound is making mechanical, physical, chemical and weak heat influence. Mechanical influence is stipulated by alternating acustic pressure, that causes microvibration and a unique kind of micromasage to tissues.Heat influence causes the growrth of temperature in tissues, promotes better blood circulation, as the result the tissue proccesses activate and the whole influence give uniflammatory action. Because ultrasound can be used selectively, it found its usage in such techniques as kidney stones or gall ball stones breaking.

Radio waves –MRI imagining
MRI imagining is based on the generating of strong magnetic fields and radio waves instead of x-rays that allows producing very clear images of all body parts. MRI is nearly the only one means of providing soft tissue clear and contrast examination.
Basically MRI unit consists of a large cylindrical magnet, generators and receivers of radio waves and a computer, that allows getting an understandable image of the examination.
The strong magnetic fields that are generated by the MRI unit prepare human’s body to emit radio waves. The magnetic field makes nuclei in atoms inside of the certain tissue of human body to line up after that the radio waves are directed at the nuclei. In the case when the frequency of the radio waves equals to the frequency of radio waves emitted by the atom, a condition of resonance takes place. The condition of resonance allows the atom to absorb th energy of the radio waves and lately when the wave stimulation will stop, the nuclei of atoms will aspire to the initial state (a well known law of inertia, from kinematics) and so they’ll return the weak radio signals and return to their initial condition. The strength and wavelength of the radio waves emitted the nuclei of atoms will be produced into a computer image, after the computer will make needed calculations and builds a model. As it’s obvious abnormal cells have different structure from those that are healthy and they’ll emit waves of different wavelengths from normal cells that will be identified clearly on the resulting image.

MRI technology:
Known advantages of using MRI: it’s an important diagnostic tool because of its abilities that help the physicians to identify any type of abnormal tissues in the human body without the usage of x-rays or diagnostic operation, used before as the only way of examination. MRI is both safe and painless, and has no known side effects, typical for other means of diagnostics.
Infrared waves-heat lamps.
Infrared light or infrared radiation is invisible electromagnetic radiation with frequencies in the range from 0.74 microns to 1mm.Any heated body can be the source of infrared radiation. Many objects that are pure for usual visible light don’t let infrared radiation pass. For example a water layer several millimeters wide is not pure for infrared lights, while a piece of black paper is pure for infrared red.
Infrared light is used in the medical diagnostics because it allows taking the temperature map of the human’s body and judging one’s health by this data.
The most simple transformer of infrared light to visible light is a device that has double glass walls and double bottom with no air in. On the inner side of the bottom there is partly transparent photo cathode and on the other side of the wall there is a luminescent screen. With a help of special lenses the image in infrared lights is projected on photo cathode. By the influence of infrared beams photo cathode begins to emit electrons, moreover the intensity varies as the brightness of infrared beams varies as well. Because of the high potential difference caused by high voltage applied between the screen and the cathode, the electrons accelerate and bombard the screen at the same time causing it’s luminary state. The intensity of the luminescence of the separate dots on the screen depends on the stream of electrons density, as the result appears visible image of the testing object.
Red Light and infrared Light Therapy
As the research shows over 40 years the testing of red-light therapy and treatment had proved that it positively influenced human tissues on the cell level. Either visible red (400nm – 700nm) or invisible infrared light (700nm – 2000nm) appeared to show aproximately 24 different positive cell changes. Visible red light, with a wavelength near 660 nm , penetrates into human tissue cells as deep as about 8-9 mm. It really helps curing skin problems among which are :wounds, cuts, scars, trigger points, or acupuncture points. It’s also an effective mean of infections treatment. Infrared light penetrates as deep as 30-40 mm which makes it very effective for treatment ofbones, joints, deep muscles, etc. Even though that ifrared light and red light penetrate to the different level of depth their influence and way of treatment are basically similar…

Wavelength cause and direct photobiochemical reactions occur on the cell level and are refered to such processes as vision, photosynthesis, tanning and metabolism of Vitamin D . From this point of view red-light and infra red light therapy play one of the important roles in modern methods of light treatment along with other methods as lasers and ultraviolet.

Lasers and their use in medicine
Laser or “Light Amplification by Stimulated Emission of Radiation” is a relatively new source of light that was introduced only in 1960th.
The basic scheme of the laser is quite simple: active element, located between two mutually parallel mirrors. Mirrors form so called optical resonator; one of the mirrors is made only partly mirrored, a laser beam is coming through this mirror out of the resonator. In order to begin generation of the laser radiation, it’s necessary to transform energy to the active element from some kind of energy source.
Let’s look on the example of laser with garnet and neodymium as an active element. Garnet is a pure crystal with admixture of neodymium ions. Those ions are so called active centers. Absorbing the radiation of special gas-discharge lamp, ions of neodymium get excited and later return into the initial state but emitting a photon of definite frequency.(it’s explained by Bohr’s postulates which state that when excited electrons return back from higher energy level to a lower energy level they emit photons.)
This photon can stimulate the returning into the initial state of many other excited ions of gas and in that case an avalanche of photons with the same frequency will be formed, moving in the same direction (the phenomenon of forced light emitting). But another variant can also take place- photon is absorbing by another resting ion (the phenomenon of resonant absorbing). It’s important that forced emitting of photons dominated on the resonant absorbing of photons. In order this to happen, it’s necessary to perform new energy transmission to the active element, so that the number of excited ions will be more then the number of resting.
But it’s not all. It’s necessary as well, that the processes of forced emitting of

Absorption of energy by atom:
An atom is able to absorb energy of heat, light, or electricity. Electrons are able to move from a lower-energy orbits to the higher-energy orbits.

photons develop in the certain direction in space. Their common optical axle
determine the direction in which the laser light is formed.
Let’s imagine that the primary photon accidentally was born in the direction different from the direction of mirror’s axle resonator. It would force the appearance of a stream of other photons but all of them will soon leave the active element, and will leave the bounds of environment. Another thing if primary photon was accidentally born in the direction of resonator’s axle. Reflected from the mirror the stream of photons, formed by the first one will return back into the active element and will force the birth of new photons. So by the means of such processes, a huge stream of photons will be moving between the mirrors, quickly increasing as the result of forced emitting processes. Exiting from the resonator through one of the mirrors this stream will form a laser beam. This is the very brief description of laser’s physics.

Laser’s treatment.
The heat effect of lasers on human’s body tissue is a complicated process that is a result of basic three phenomena; transformation of light into heat, the heat transferring and tissue’s reaction on acting heat.
This mutual reaction causes the denaturation of a certain volume of tissue. The basic factors of these processes are the laser parameters such as wavelength, frequency, power, emission mode, and the size of the laser spot.
Laser’s treatment.
PRK is a type of refractive operation, that gently changes the shape of the cornea of eye, by the means of removement of microscopic amounts of tissue from the surface by a cool, controlled by computer ultraviolet beam .. The procedure of the surgery takes not more than few minutes, and patients usually return back home the same day the surgery was made.
Before the surgery the eye of the patient is exemineted and the model of the eye is being created by the laser’s computer. After it determines the shape problem the operation begins.
Since 1995, only several laser systems were approved by health authorities of the USA, because of a remaining risk to health.
Even so that laser based operations are considered to be very successful, at least 5% all patients who experienced these operation still had to need glasses.
LASIK is generally thought to be a more complicated surgery than PRK. It is made for all degrees of eyesight related problems. In LASIK a surgeon also uses a knife called a microkeratome for cutting a flap of corneal tissue, then he removes the tissue, he had targeted, with a help of laser, and after that he replaces the flap.
Laser is also used in urology, oncology and other branches oif medicine where it’s important to make very precise incisions on the hand with accuracy and sanitary.

Endoscopy
Endoscopy is a mean of internal body examination that allows physicians to penetrate and examine body organs, joints or cavities, by the usage of endoscope. Endoscope is basically a system of fiber optics and a system of powerful lens that provides enough lighting and visualization of the subject of examination. The part of the endoscope that is inserted into human’s body is very flexible so that it doesn’t injure the organs.
An endoscope’s working part is basically two fiber optic cables, one of them is for lighting the body’s cavities and another one carries back the image of the subject of examination to the physician’s lens. More advanced endoscopes can be equipped with camera or video recorder, or even a computer, for future data storage or analysis.

This image shows a rigid endoscope which is basically used for arthroscopy. The “image fiber” goes all the way from the ocular lens (eye piece) to the end of the scope. The “light fiber” is shown below and goes all the way from the light source to the working part (end) of the endoscope.
Optical fibers are based on the effect of total internal reflection. Optical fibers are thin curved fibers from the optical pure material. Fiber details are made of glass like fiber, the light conductive part of the cable is surrounded by the glass cover of another kind with less coefficient of refraction. Light, that is falling on the light conductor with the angles, that have a bigger a value than a critical one, feels the total reflection on the surface of division of conductive part and cover and then it’s expanded only by the light conductive “vein”.
By means of that it’s possible to distort anyhow the way of light beam. The diameter of such optic fibers varies from several microns to several millimeters. For the transmission of imagines usually multiple optic fibers are used.

Ultraviolet waves – skintreatment
Ultraviolet waves or ultraviolet radiation is ways with wavelength in the range from 400 nonometers to 10 nonometers, which is taking the most short-wave part of optical spectrum. Natural sources of ultraviolet radiation are stars, Sun, and other space objects; artificial are gas-discharge lamps, laser systems.
Treatment by means of ultraviolet uses a definite range of the nonvisible light spectrum to cure psoriasis and a set of other skin diseases. Ultraviolet treatment can be used along or in the combination with other kinds of treatment..
UV-B, from 280 nm to 315 nm as well as UV-A, from 315 nm to 400 nm(but rarely)
is used in psoriasis treatment. It kills abnormal skill cells or also can alter and stimulate immune system in skin tissues.
UV-C, from 100 nanometers (nm) to 280 nm is used to deactivate the DNA of such biologicaly dangerous species for human as bacteria, viruses and other pathogens. In particular, UV-C light is the reason of damaging the nucleic acids of microorganisms by forming covalent bonds between certain adjacent bases in the DNA of that kind of microorganism. It makes unable a microorganism to reproduce, actually when it’s trying to reproduce it dies.
The construction scheme of ultraviolet bulb

The most of the ultraviolet lamps produced by nowadays industry use mercury vapor tubes with low pressure that as the result emit ultraviolet waves that are mortal to micro-organisms as viruses and bacterias.. Nearly 95% of the ultraviolet wave’s energy created lies at the mercury resonance of 253 nanometers

X Ray-CT/CAT scans
CAT scanning is used by physicians to examine the body organs on the subject of different abnormalities. Nuclear medicine also allows non invasive diagnostics to the patients without any kind of surgical penetration into human body. Nuclear medicine methods give doctors more abilities to examine and look inside the human body. These methods unite the usage of computers, detectors and radioactive substances.
Basically nuclear medicine examination is helpful for distinguishing:
Cancer tumors
aneurysms (weak spots that are usually detected on blood vessel walls)
abnormal blood flow to different types of tissues
blood cell abnormalities and disorders in functioning of organs, for example thyroid or pulmonary function deficiencies.
Computed Tomography (CT) is based on the x-ray radiation principals: as x-ray passes through it is absorbed at differing levels so that it creates a matrix or profile of x-ray beams of different kind of its strength. The x-ray profile is the registered on film, so creating an image.
During the procedure of CT scan, the patient is aired by a radioactive substance, placed on the table that is moving through a “doughnut”-looking housing. This housing shaped equipment has a circular gamma radiation detector system, which is formed by a system of scintillation crystals, which are all connected to the photomultiplier tube. These crystals transform the gamma ray radiation which is emitted from the examinee, to the photons of light, and then photomultiplier tubes transform intensify the photons to electrical signals(the concept of photo effect. To be more specific the photo effect is based in the following: under the influence of gamma radiation, atom absorbs gamma quant of energy and emits electron. Because the emitted electron is exiting from his energetic level this vacant place is taken by the other electrons from higher orbits, so photo effect is followed by roentgen radiation. Photo effect can take place only on united electrons, because a free electron can not absorb gamma quant, on the other hand this process will not answer the basic physics laws of energy and momentum conservation. ). As the table is moving the entire process is repeated again and again, and as a result the series of small images of the whole body over the are of the examination form the whole picture of what is happening. By the means of computer modeling these images can be converted into three dimensional pictures.
CT is considered to be one of the most reliable instruments for checking the lungs and abdomen. CT is of a great value tool in the cancer diagnostics and is often the most widely used method for lungs, liver and pancreas cancer diagnostics. The abilities that CT gives for imaging and angiography are becoming more popular are in the ditinguishing, detecting and curing of different forms of heart diseases, stroke and vascular system diseases, which can cause stroke, as well as gangrene or kidney deseases . In addition, CT can also be used for measuring of bone mineral density for the test on osteoporosis.

Gamma rays. Gamma ray camera, radiotherapy.
Radiotherapy, with another name radiation therapy, is the treatmenof cancer and cancer related deseases by means of ionizing radiation. This kind of radiation contains energy which destroys or deadly influences the cells in the treating area. (the “target tissue”) By damaging their DNA, radiation makes impossible continity growrth of these cells. Even though that radiation demages cancer cells along with healthy normal cells, still the last are able to grow and regenerate.. Radiotherapy can be used for treatment of different kinds of tumours, especially in the cases when surgery is not desirable.
Gamma rays are used on the hand with X-rays in cancer treatment. They are a form of photons that is used in radion therapy. Gamma rays are produced spontaneously as a result that certain radiactive elements (for example radium or uranium, or cobalt 60) emit radiation as they decay. Each particular element decays at his own particular rate and releases energy which is gamma rays with other particles. Generally both x-rays and gamma rays have the same influence of the cells.

How laser works
1. A laser in it’s initial state(non excited )
2. The flash tube starts working and excites the ions of gass.
3. As a result some of these atoms start emitting photons.
4. And at least monochromatic light leaves the half mirror-laser light

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