To trace the energy of an electron from the time it enters the x-ray circuit until it’s converted to light, start with a standard U.S. 60-HZ AC (alternating current) wall circuit with a nominal root mean square (rms) voltage of 220. An alternating current is created by, electrons moving in one direction and then reversing to move in the opposite direction. Because of this process in electron motion the AC is constantly establishing, collapsing, reestablishing, and re-collapsing its surrounding magnetic field. The incoming line current will supply power in the form of a three-phase power cycle to the main x-ray circuit and filament circuit. A generator, converting mechanical energy to electrical, provides three-phase power. This creates the …show more content…
It is within the x-ray tube x-ray photons are created. As a result of electrons moving from cathode to anode, x-rays are produced. The cathode end of the tube is considered the negative side of the x-ray tube. The main purpose of the cathode is to produce the thermionic cloud, otherwise known as thermionic emission. The cathode filament, which is set inside the focusing cup, must produce sufficient resistance to the flow of electrons to create enough heat to form the thermionic cloud. This is the process that takes place when ejected electrons from the surface of the filament wire increase in heat causing the cloud. The filament circuit and the high voltage main circuit come together at the cathode end of the tube providing the high voltage necessary for x-ray as well as the correct amperage. When the exposure switch and rotor button are held down simultaneously the thermionic cloud of electrons is driven toward the anode target where x-ray photons are produced. At this point some electrons are vaporized, some reach the anode, and some are changed to photons. The anode is the positive side of the x-ray tube. The anode is where electrons become photons, it conducts the high voltage from the cathode back into the x-ray generator circuitry, and serves as the primary thermal conductor. The anode assembly consists of a rotor, stator, and for general diagnostic x-ray a …show more content…
The photons that pass through the body unaffected will reach the image receptor to create the image. These photons create the contrast visible on the image. Absorption of the photons takes place due to the photoelectric interaction. Photoelectric absorption results in the primary photon being completely absorbed, which produces a secondary photon that gets quickly absorbed into surrounding tissues. Compton interactions are strong enough to be emitted by the patient and interact with the image receptor creating a decrease in contrast. Less scatter is produced in bone as opposed to soft tissue. A grid is used in radiographing larger body parts because of the amount of soft tissue being penetrated. Once the photons have been absorbed or passed through the grid they form the image in the image receptor. In a CR (computed radiography) system a reusable photostimulable phosphor image receptor is used. The photostimlulable phosphor plate (PSP) is a rigid sheet with many layers that are made to record and enhance the transmission of the image from a beam of ionizing radiation. The many layers that comprise a PSP are the protective layer, a phosphor layer, a support layer made of polyester, a conductive layer, and a light-shield layer. The phosphor layer of the PSP is the active layer where the photostimulable phosphor creates the latent image. The phosphor is made of
In dentistry there is a need for taking an x-ray, the x-ray is a way to help the dentist diagnose a patients oral hygiene and to see if there are any other areas in the mouth that may need to have any type of work. The dentist or the assistant will want to make sure that they can get all the teeth possible in the radiograph (x-ray) as possible to reduce the amount of exposure to the patient. Most people will have exposure to radiation just from standing outside in the sun for a long period of time, which is what we call “background exposure”.
All of the sources of current to the equipment should be isolated and signs need to be fixed to ensure that the nature of the equipment is known
These gamma rays, produced by the annihilation of a positron and an electron, leave the patient’s body and are detected by the PET scanner. The detection of positron-annihilation events forms the heart of any PET scanner. In most systems, the Gamma detector is a BGO (bismuth germinate oxide) crystal, a high-density scintillator. When it is combined with high performance photomultiplier tubes (PMTs), the detection of 511 KeV gamma rays is possible.
Zondy, David . "Tesla's Death Ray." davidszondy. 23 March 2011. Web. 10 Sept. 2011. .
on the primary beam is that it limits the x-ray beam field size. The beam restricting device alters
Driver, (2013), described the DEXA scanner as a machine that produces two x-ray beams of high and low energy levels. Much like fluoroscopy, the x-ray from the DEXA scanner comes from underneath the patient, and the scanner has a very low x-ray dose. Earlier versions of the DEXA scanner emitted radiation which required up to five minutes to scan an area of interest, but the more advanced machines can take as ...
...s in one direction to acquire a single image slice. For another slice to be imaged the x-ray tube would again rotate another 360 degrees but on opposite direction. However this has been changed over the years and has been implemented a Slip-Ring technology which replaced the old high tension cables. In this way the new CT scanner x-ray tube had the ability to rotate continuously around the patient and in the same time the table was moving through the gantry to acquire data in a form of a Spiral or Helical. Therefore the new generation of CT scanners is called Spiral or Helical CT. The advantages of the new scanners are that the volume data can be reconstructed in any other planes (sagittal, coronal and three dimensional images), also there is a short time scan therefore radiation to the patient is minimized and also the artefact caused by patient motion is reduced.
Radiation is something that the naked eye cannot see, yet has the potential to save lives one treatment at a time or even one image at a time. Since the discovery of x-rays in 1895, it has branched out into numerous modalities each independently specializing in their own ways. X rays are used to aid in the diagnosis and treatments of patients on a case by case scenario. Sometimes doctors can make a diagnosis on the same day or conclude that a patient will require radiation therapy within weeks to follow. Whatever it may be, the importance of x rays and radiation itself is a crucial part of the medical field when it comes to saving lives. Initially it all started with the discovery of x rays but then three years later radiation therapy was introduced to aid with
It does seem that are world is almost always in a state of confusion and even more
Since physics actually means the physical world; Meta involves the non-material world, such as the mind and spiritual brief. According to Encarta Encyclopedia, “Metaphysics,” is a branch of philosophy that entails the "nature of ultimate reality" (p.1) According to the Hummingbird N Company’s, “The Metaphysical Sciences,” the dictionary defines this as “A mental philosophy dealing with the nature and causes of being and knowing” (p.1). H. J. Patton (1948), say’s in Immanuel Kent Ground Work of the Metaphysics of Morals, “so act that your will can regard itself at the same time universal law thought its maxim” (p.34). The interoperation was that the universal law was the human’s as rational beings. Therefore, act, as you will but at the same time having the rational beings at the maximum of self-value. Patton goes on to say the rational being is having universal law at is maxim, is giving ones self-supreme value (p. 35). Therefore, Patton feels making decisions should be based on maxims of the universal law (p. 108). Which means all decisions should be made rationally.
The CRT monitors work in a fashion similar to that of standard television sets. An electron gun is mounted at the back of the monitor. The gun fires a steam of electrons in a sweeping motion towards the front of the monitor. The electrons then pass through either an aperture grille, or a shadow mask. These items work to filter the electrons into focused beams onto the front plate. The grill does this via thin vertical wires, while the mask does this with a series of small holes. After passing through the filter, the electrons collide with the screen. The screen is covered with a serried of red, green and yellow phosphors that light up when hit by the electrons. By combining different intensities of the three colors, many different colors and images can be created.
Computer games have steadily become a form of mainstream entertainment ever since Pong was released back in 1958. Today, it is hard to find an electronics department in any store that doesn't carry some sort of computer game. "Big deal," you say, "Everyone knows about computer games. What does they have to do with physics?" Well, the technology for creating more powerful software is constantly advancing, and since games are a form of software, they too become more and more advanced. As games become more advanced, game developers aim to create games that offer a more realistic experience. The technology has advanced to such a stage that making the games look real is no problem, but making a truly immersive experience is something different. That's where physics comes in.
Tesla designed and invented the tesla coil in 1891. The tesla coil is used to transmit- high electricity and high frequency using the rotating magnetic field, and Alternating Current similar to the design he used for the rotating magnetic field. Tesla often experimented using two or sometimes three of the coils. He wanted to pursue these new devices to bring about innovations and discoveries. Tesla was also going to use them to help deliver free energy to the people. He envisioned and believed the Earth to be a big magnet of transmitting electricity. He thought the only thing missing from it was basically a receiver. But his tesla coils helped him bring about the invention of electrical lighting, his very used and widely-known x-ray, electrotherapy, and as I have previously stated, this was his first step at trying to receive energy from the earth. Today, the tesla coil is used for amusement and in some cases, they are used to identify leaks in a vacuum system. So how does the tesla coil work? They start off with a simple spark to set it off. Oscillators, I believe I mentioned them in the history of Tesla, they are basically used to help deliver an oscillating current. The oscillator helps the coils produce currents that can range anywhere from 50 kilovolts to several million volts of electricity. This is what your typical mad scientist use in things such as Frankenstein. Except for Tesla was a very real version of those mad scientists. The tesla coil also had a capacitor in it, they are used to store an electrical current that bursts out to help it create a stronger voltage. I have also read that there is something in it called a spark gap which is a switch in the coil to turn it on. Since I have let you know what the machine consists of, I will now discuss the operation cycle. First, the transformer sends high voltages up to the capacitor. There is something called a breakdown voltage there.
As x-rays exit the patient, they interact with a cesium iodide input phosphor which converts the x-ray energy into visible light. Cesium iodide crystals are a tightly packed layer of linear needles which help improve spatial resolution by allowing little light dispersion. Attached to the input phosphor is the photocathode. Bushong describes the photocathode as, “a thin metal layer usually composed of cesium and antinomy compounds that respond to stimulation of input phosphor light by the emission of electrons.” (Bushong, 2013, p. 405). This phenomenon of electron emission following light stimulation is called photoemission. The emission of just one electron through photoemission is dependent upon numerous light photons. The amount of electrons produced by the photocathode is directly proportional to how much light reaches it from the input phosphor, which is directly proportional to the intensity of the initial x-ray beam. These electrons will be accelerated to the anode where they will pass through a small hole to the output phosphor. The output phosphor, made of zinc cadmium sulfide, is where the electrons produced through photoemission will interact and produce light. It is extremely
Thermodynamics is the branch of science concerned with the nature of heat and its conversion to any form of energy. In thermodynamics, both the thermodynamic system and its environment are considered. A thermodynamic system, in general, is defined by its volume, pressure, temperature, and chemical make-up. In general, the environment will contain heat sources with unlimited heat capacity allowing it to give and receive heat without changing its temperature. Whenever the conditions change, the thermodynamic system will respond by changing its state; the temperature, volume, pressure, or chemical make-up will adjust accordingly in order to reach its original state of equilibrium. There are three laws of thermodynamics in which the changing system can follow in order to return to equilibrium.