PP-W Physics

  1. What is an atom?
    A fundamental unit of matter
  2. Atomic Structure of an Atom consists of
    • Central nucleus: Contains the protons (+) and neutrons (no charge) particles AND
    • Orbiting electrons: Contains negatively charged particles
  3. What is ionization?
    Process of converting an atom into ions
  4. An atom that gains or loses an electron and becomes electrically unbalanced is known as an _____.
  5. Ionization deals only with
  6. What is ionizing radiation?
    Radiation that is capable of producing ions by removing or adding an electron to an atom
  7. Ionizing Radiation is classified into what two groups
    • Particulate Radiation 
    • Electromagnetic Radiation
  8. What is particulate radiation?
    Tiny particles of matter that possess mass and travel in straight lines at high speeds.
  9. What is Electromagnetic radiation?
    • Propagation of wavelike energy(without mass) through space or matter
    • Man-made or occur naturally
  10. In particulate radiation Electrons are classified as
    beta or cathode rays
  11. Cathode rays are
    streams of high-speed electrons that originate in the x-ray tube
  12. Beta particles are
    fast moving electrons emitted from the nucleus of radioactive atoms
  13. What are some examples of electromagnetic radiation
    • Cosmic rays
    • Gamma rays
    • X-rays
    • Ultraviolet rays
    • Visible light
    • Infrared light
    • Radar waves
    • Microwaves
    • Radio waves
  14. Electromagnetic Radiation is arranged according to their energy in an
    Electromagnetic Spectrum
  15. Only the high energy radiations are capable of ionization such as
    cosmic, gamma, and xrays
  16. The particle concept Characterizes electromagnetic radiations as
    discrete bundles of energy called photons
  17. What are photons?
    • bundles of energy with no mass or weight
    • travel as waves at the speed of light- move thru space in a straight line
  18. The wave concept characterizes electromagnetic radiations as ________ and focuses on the properties of ________, _______, and _______
    • waves
    • velocity, wavelength, and frequency
  19. What is velocity
    speed of the wave
  20. What is the wavelength
    distance between the crests of the waves/determines the penetrating power of the radiation
  21. The shorter the distance between two crests, the shorter the wavelength, and the ______ the energy
  22. What is the Frequency
    Low frequency = _____ wavelength
    • The number of wavelengths that pass a given point in a certain amount of time
    • Long
  23. Low frequency=Long wavelength=_____ energy=______ penetrating power
    High frequency=Short wavelength=_____ energy=______ penetrating power
    • Low
    • Less
    • High
    • More
  24. What is x-radiation are what are some properties
    • High-energy, ionizing electromagnetic radiation
    • Possess properties of both waves and particles
    • Defined as weightless bundles of energy (photons) without an electrical charge that travel in waves with specific frequency at the speed of light
    • X-ray photons interact with the materials they penetrate causing ionization
  25. What is the appearance, mass, charge, speed , wavelength, path of travel and focusing capability of x-rays?
    • Invisible
    • No weight or mass
    • Have no charge
    • Short wavelengths, high frequency
    • Travel in waves; at the speed of sound through space in a straight line that can be deflected/scattered
    • Cannot be focused to a point, always diverge from a point
  26. What is the penetrating power, absorption, ionizing capability, fluorescence, effect on film and effect on tissue of x-rays?
    • Penetrates liquids, solids and gasses
    • Absorbed by matter
    • Causes ionization with materials they penetrate (process of converting an atom into ions)
    • Causes certain substances to fluoresce (Barium, Magnesium)
    • Can cause biological changes in living cells
    • Can produce an image on photographic film
  27. What are the components of an X-Ray Unit
    • Control Panel: On/Off switch and Control devices for time, kilovoltage and milliamperage
    • Extension Arm: Allows movement and positioning of tubehead, extends from control panel to tubehead and houses the electrical wires
    • Tubehead: Contains the xray tube where xrays are produced
  28. What are the components of the tube head
    • Metal housing
    • Insulating oil
    • Tubehead seal
    • X-ray tube
    • Transformer
    • Aluminum disks
    • Lead collilmator
    • PID (extends out from the tubehead)
  29. What is the function of the metal housing in the tube head
    Protects the x-ray tube and grounds the high voltage components
  30. What is the function of the insulating oil in the tube head
    Prevents overheating by absorbing the heat created by the production of x-rays
  31. What is the function of the tubehead seal in the tube head
    Seals the oil in the tubehead and acts as a filter to the x-ray beam
  32. What component of the tubehead is considered the heart of the x-ray generating system
    x-ray tube
  33. What is the function of transformer in the tube head
    Alters incoming electricity
  34. What is the function of aluminum disks in the tube head
    Filter out non-penetrating, longer wavelengths
  35. What is the function of the Lead collimator in the tube head
    Restricts the size of the x-ray beam
  36. Describe the PID
    Open-ended, lead-lined cylinder that aims and shapes the xray beam
  37. X-ray tube is a
    • glass vacuum-sealed tube
    • Critical in the production of x-rays
  38. What are the components of the x-ray tube?
    • Leaded Glass Housing
    • Negative Cathode
    • Positive Anode
  39. What is the function of the Leaded-Glass Housing (Tube) of the x-ray tube
    • Vacuum tube prevents x-rays from escaping in all directions
    • One central area has a window that permits xray beam to exit the tube
    • Directs beam toward the aluminum disks, lead collimator, and PID
  40. The cathode consist of:
    • Tungsten wire filament
    • Produces electrons when heated
    • Molybdenum (focusing) cup
    • Focuses the electrons into a narrow beam and directs it across the tube toward the tungsten target of the anode
  41. mA (milliamperage control) regulates the _______ transformer, the quantity of xrays produced and heating of the filament of the _______
    • step-down
    • cathode
  42. The anode consist of:
    • Consists of a wafer-thin tungsten plate embedded in a solid copper rod
    • Tungsten plate (target) serves as a focal spot where bombarding electrons are converted into xray photons
  43. Kilovoltage control(kVp) regulates ______ transformer, voltage between cath and anode, and ________
    • step-up
    • speed of electrons
  44. What is the function of the copper stem of the anode
    Dissipates the heat away from the tungsten target
  45. _____ is the energy used to make x-rays. Consists of a flow of electrons through a _______ . This flow is known as the _________
    • Electricity
    • conductor
    • electrical current
  46. The step down transformer is used to
    Decreases the voltage from the incoming 110 or 220 line voltage to 3 to 5 volts used by the filament circuit (Cathode)
  47. The step up transformer is used to
    increase the incoming 110 – 220 volts 65,000 to 100,000 volts
  48. The Autotransformer is the
    Voltage compensator that corrects for minor fluctuations in the current flowing through the xray machine
  49. What are the steps of x-ray production when the machine is turned on
    • 1. Electricity enters the control panel from the wall outlet
    • 2. Current travels from the control panel to the tubehead through the electrical wires in the extension arm
    • 3. Current is directed to the filament circuit and the step down transformer (110 or 220V to 3-5V) in the tubehead
    • 4. Filament circuit uses the 3-5volts to heat the tungsten filament in the cathode
    • 5. “Thermionic Emission” occurs: the release of electrons from the tungsten filament when the electrical current passes through it and heats the filament (“boiling-off” of electrons creates an electron cloud)
    • 6. Outer-shell electrons of the tungsten atom acquire enough energy to move away from the filament surface and an electron cloud forms 
    • 7. Electrons stay here until the high voltage circuit or step up transformer (110-220V to 65,000-100,000 V) is activated
  50. What are the steps of x-ray production when the exposure button is pressed
    • 1. When the exposure button is pushed, the high voltage circuit is activated (step-up transformer)
    • 2. Electrons produced at the cathode are accelerated across the xray tube to the anode
    • 3. Electrons strike the tungsten target and are converted to xray energy (<1%) and heat (>99%)
    • 4. A small number of xray photons exit through the unleaded glass window
    • 5. X-ray beam then travel to the tubehead seal, and the aluminum disc (filter).
    • 6. Aluminum discs remove (filter) the ineffective low energy, non-penetrating longer wavelength xrays from the beam
    • 7. The size and shape of the xray beam is next restricted by the collimator and travels down the lead-lined PID (aims and shapes the xray beam) and exits the tubehead
  51. Kinetic energy of electrons convert to xray photons through what 2 mechanisms
    • General (Braking) Radiation 
    • 2) Characteristic Radiation
  52. General (Braking) Radiation is and produces what percentage of the x-ray energy produced at the anode
    • Speeding electrons slow down due to interaction with tungsten target in the anode (hits or near-misses nucleus of tungsten atom) thus producing xray photons
    • Braking Radiation=“Bremsstrahlung”(German term that means braking radiation)
    • 70%
  53. Characteristic Radiation is produced when
    • a high speed electron dislodges (ejects) an inner-shell electron from tungsten atom and causes ionization from that atom
    • Remaining electrons are rearranged to fill the vacancy, resulting in the production of an xray photon
    • Accounts for a very small part of xray production and only at 70 kVp and above
  54. Primary radiation (“useful beam”):
    x-ray beam that exits the PID
  55. Secondary radiation
    created when the xray beam interacts with matter (soft tissues, bones, teeth) Less penetrating than primary
  56. Scatter radiation
    a form of secondary radiation that results from an x-ray that has been deflected from its path due to interaction with matter. Deflects in all directions and is detrimental to pt. and operator
  57. What are the (4) Interactions of X-Radiation with Matter
    • X-ray photons can pass thru pt. w/ no interaction:   leaving atoms unchanged and producing densities/ images on receptors
    • Completely absorbed by pt. (photoelectric effect/ionization): 30%
    • Scattered (changes direction): most of scatter radiation is Compton scatter (ionization): 62%)
    • Coherent/unmodified scatter (photon is not modified and no ionization or change in the atom occurs; xray photon just changes direction : 8%)
  58. Describe Compton scatter radiation
    • X-ray photon collides with a loosely bound outer-shell electron and gives up part of its energy to eject the electron from its orbit
    • X-ray photon loses its energy and continues in a different direction at a lower energy level
    • Ionization occurs
    • Partial absorption occurs
  59. Describe the Photoelectric Effect (30%)
    • X-ray photon collides with a tightly bound inner-shell electron
    • Gives up all its energy to eject the electron from its orbit
    • All of the energy of the photon is absorbed
    • Ionization occurs
    • Total absorption occurs
  60. Describe Coherent Scatter (8%)
    • Path of a low-energy xray photon interacts with an outer-shell electron
    • No change in the atom occurs
    • No ionization occurs, xray photon just changes direction and is unmodified
  61. Ampere:
    Unit of measure to describe number of electrons (or current) passing through the cathode filament
  62. Milliamperage (mA) regulates the
    temperature of the cathode filament and the QUANTITY (#of xrays)
  63. When mA is increased, ________ must be decreased
    exposure time
  64. Increase in mA = ________ in density
    increase (darker image)
  65. Decrease in mA= __________ in density
    decrease (lighter image)
  66. Beam Quality is the
    penetrating ability of the x-ray beam
  67. Beam Quality or wavelength is controlled by
  68. Voltage determines the _______ of electrons that travel from cathode to anode
  69. Dental Radiography requires ____kV
    65 to 100kV
  70. Contrast is _____
    Low (65-70) kVp= _______ contrast
    High (over 90) kVp= _______ contrast
    • how sharply dark and light areas are differentiated or separated on an image
    • high contrast (few shades of gray, mostly black and white)
    • low contrast (many shades of gray)
  71. Exposure time is measured in _____
    __ impulses in 1 second
    • Impulses
    • 60
  72. When kVp is increased by 15, Exposure time is _______
    When kVp is decreasd by 15, Exposure time is
    • decreased by half
    • doubled
  73. INTENSITY of the xray beam is affected by
    kVp, mA, exposure time and distance
  74. _________ affects the # of xrays produced
    Exposure time (as with mA)
  75. Target-surface distance
    source of radiation to patient’s skin
  76. Longer PID’s result in
    • Less divergent xray beam
    • Decreased radiation exposure to pt
    • Less image magnification
  77. When PID goes from 8 to 16 inches, the resultant beam is __ as intense
  78. When PID goes from 16 to 8 inches, the resultant beam is ___ times as intense
  79. Aluminum filters increase the _________ of the beam while reducing the ________
    • penetrating capability
    • intensity
Card Set
PP-W Physics
PP-W Physics