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Who discovered x-radiation? |
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| ___________ is a form of electromagnetic radiation. |
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| ____________ is energy passing through space as waves. |
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| ___________ consists of oscillating electric and magnetic fields moving through space at _____ angles to each other |
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| · Electromagnetic radiation consists of oscillating ______ and ______ fields moving through space at right angles to each other |
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| · Types of radiation differ in their properties and depend on ______ and _______. |
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| Velocity of the Wave= ? x ? |
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| What speed do x-rays travel at? |
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| For all forms of EM radiation, the velocity is the same. What is the velocity? |
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| · All EM radiations are forms of _____. |
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| The energy carried by the radiation |
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Compared to visible light, x-ray photons have greater velocity shorter wavelength lower frequencdy less energy |
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X-ray photons have shorter wavelength and higher frequency... so shorter wavelength |
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| The distance between seccessive peaks in a wave |
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| Number of waves that pass a point in a unit of time |
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| Mathematically, how is wavelentgh related to frequency? |
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| they are inversely proportional |
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| Proportional to frequency of wave, and inversely proportional to wavelength |
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| Radiation with enough enough energy to ionize atoms in absorbing material |
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| X-rays have no ____ and no _____. |
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| x-rays are waves passing thorugh spacee with very ____ wavelengths and _____frequencies |
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| X-rays have such great energy they behave like particles and can _______? |
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| A vaccuum glass tube with cat hode filament and anode target |
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1. Electroms emmitted from filament. 2. Electroms drawn across x-ray tube at high speed. 3. Electrons collide with target, converting kinetic energy into EM radiation. |
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| When xrays are produced, a filament is heated by an electric current to boil off electroms. What is this called? |
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| When x-rays are produced, what forms around the filament? |
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| electrons form a cloud/space charge |
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| Electrons are drawm across tube through the procudtion of (+) ____ with respect to the (-)______. This is called ________, and is measured in ____. |
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anode end, cathode end, potential difference, kilovolts |
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| Electroms moving across the tube from the cathode filament to the anode target produce the ____, measured in milliamperes. |
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| tube current, milliamperes. |
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| Where are electons focused at? |
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| the anode target/ focal spot |
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| 99% of electron interactions produce ____ , only 1 % produce _____. |
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| The length of time the electrons move across the tube is |
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| exposure time (measured in seconds/impulses) |
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| When voltage is changing, the anode is not always (+) with respect to the cathode. Electons move across tube only in half the cycle when anode is ____. |
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| x-rays are not procuced _____, but in _____. |
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| X-rays are ____ impulses per second. |
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| Whats in the nucleus during x-ray production? |
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| protons and neurtons, net (+) charge |
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| holds electrons in orbit around nucleus; greater in elements with more protons; greatest for all electrons in the K shell closest to nucleus |
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| Binding energy is greatest for electons in the ____ shell. |
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| Electrons encounter anode and interact in two ways: |
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| Brehmsstrahlung radiation, and characteristic radiation |
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| Brehmsstrahlung Radiation |
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| § Most attracted to positive charge of protons in nucleus § Approach nucleus, are slung around it, slow down § Some hit nucleus and stop § When slow down, converts kinetic energy into EM radiation § Electrons “put on brakes” = brehmsstrahlung (German) § 85-90% x-rays produced this way § X-rays are polyenergetic (multiple energy levels) § Slow down at various rates Range of kinetic energies due to varying kilovoltage
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| § Some electrons directly hit a K shell electron and ionize it § Vacancy in K shell so an L shell electron drawn into K shell due to greater binding energy of K shell § As electron moves it emits energy equal to difference in binding energies between L and K shells § Only tungsten, only K & L – x-ray produced, can occur with other shells but no x-ray is produced § Energy emitted is characteristic of the element, thus called characteristic radiation § Makes up 10-15% of all x-rays § Monoenergetic (one energy level) |
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An exposure time of.4 seconds is equal to how many impulses? .007 .4 4 24 40 |
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Which of the following controls the energy level of the x-ray photons? kVp mA esposure time position indicating device |
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At which part of the x-ray tube are x-rays made? filament focusing cup target added filtration |
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Which of the follwoing is true regarding brehmasstrahlung radiaion? a. makes up 85%-90 of xrays produced in the x-ray tube b. consists of x-rays with a single energy level c. results from interaction with k shell electrons in tungsten |
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Which components of the x-ray unit most directly control the energy level of the primary beam of x-rays? a. kVp and added filtration b. added filtration and exposure time c. exposure time and milliamperage d. milliamperage and kVp |
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The target of the x-ray tube is made of what material? |
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In a x-ray tube, 2 factors affect the Quantity of x-ray photons produced but no the quality of the photons. What 2 factors are they? a. milliamperage and exposure time b. exposure time and kilovoltage c. KVP and inherent filtration d. inherent filtration and milliamperage |
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| Thermionic emmission occurs at the ____ of the x-ray tube? |
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Brem. radiation a. is polyenergetic b. comprises most of the x-rays in the tube c. both d. neither |
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| We can control x-ray production by altering _____ and _____ |
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| exposure settings and collimation |
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| Difference in potential or electrical charge between the cathode and anode |
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| Voltage varies continuously bc of alternating current power supply; refer to |
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| Most radiation that we do is ____ wave radiation. |
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| electrons move fast, lots of kinetic energy |
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| elecrons move slowly, less kinetic energy |
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| Higher kVp causes a ___ image, low kVp causes a ____ image |
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| Determines the # of x-rays NOT the energy level |
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High mA make (more, less) _____ xrays? Low mA make -___ xrays? |
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High mA = ___ image low mA = _____ image |
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| Long exposure time cuases (more,less) xrays and a _____ image |
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| short exposure time causes ______ xrays, _______ image |
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mA - s= milliampere-seconds mA and exposure time control the smae thing so... mulitply them together to the # of photons in beam |
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| To keep # of photons contant, if mA is increased, time is_____ |
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| x-rays go in all directions but most are absorbed by the tube or tube head is a process called |
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| when x-rays exit tube head through diaphragm they become the |
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| Used to absorb low energy photons (weak photons are bad b/c they are absorbed in tissue) |
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| What is the added filtration at the opening of tubehead |
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| Filtration _____ the average energy of the x-ray but _____ # of photons |
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| Limits size of beam at patients tissue by absorbing divergent x-rays before they hit patient |
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| Position indicating device |
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circle, rectagle, pointed rectangular is best! PID long length is best! |
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| New exp time/old exp time= new PID length/old PID length |
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| short PID needs ____exp, long PID needs __exp |
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| three possible interaction of x-rays |
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| transmission, absorbtion, scatter |
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| hight E x-rays, low density of atoms, low thickness |
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| low E xrays, high density of atoms, high thickness |
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| high E xrays, greater electrom density |
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| Dark images have _______ radiographic density and light images have _____ radiographic density. |
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| _____ x-ray expsoure leades to _______ density |
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| Radiographic density is greater with |
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| Subject contrast, film contrast, viewing conditions |
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| x-rays transmitted though_______ tissues, absorbed through ___ tissues |
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High kVp= ____ contrast low kVp=____contrast |
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| x-rays produce many shades of grey between black and clear (high/low) kvP |
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