Ch.9 Radiography

• cephal/o


  head
• e-


  without
• graphy


  picture
• kilo-


  measurement, 1,000
• lamina

  layers
• lucent

  through
• metric


  measuring
• radio


  reception of signals
• volt


  unit of measure
• x-ray tube/vacuum tube


  produces x-rays
• cathode


  electrode in the X-ray tube that is the electron source
• filament

  tungsten coil in the cathode focusing cup that heats up to generate the electrons
• anode


  the target for the electron cloud that converts the electron force into photons
• focal spot


  target areas on the anode where rays are projected to make the primary beam, or central beam

  • smaller focal spot produces better image
• aluminum filter


  aluminum disks that are placed between the collimator attachment and the exit window of the tube to absorb weak radiation
• aperture


  opening in the lead collimator disk that regulates the size of the primary beam
• PID (position indicating device)


  has lined walls to assist collimation that is used by the operator to help align the X-ray beam with the beam alignment device
• milliampere control


  describes the quantity of the electrons that control the amount of X-rays produced for the primary beam
• kilovolt power


  the quality of the X-ray beam and controls the force that attracts the electrons to the anode
• exposure time


  duration of the interval during which current will pass through the X-ray tube; may be stated as fractions of a second or impulses
• target-film distance


  distance of the film surface from the source of radiation
• target-object distance


  distance between the anode target and the object to be radiographed
• film speed

  A (slowest) to F (fastest) speed

  • faster speed film requires less radiation exposure time for the patient
• types of X-ray radiation

  • primary radiation
  • secondary radiation
  • scattered radiation
  • leakage radiation
• primary radiation

  central ray of radiation emitting form the tube head and PID

  • the desired radiation and is used to expose radiographic film
• secondary radiation


  once the primary beam interacts with matter
• scattered radiation


  radiation deflected from its path during its passage through matter; may be deflected or diffused in all directions
• leakage radiation


  any radiation other than the useful beam produced from the tube head
• ion


  a particle that carries an electrical charge
• sensitivity


  ability of X-rays to penetrate and possibly ionize
• cumulative effect


  long-term outcome of radiation
• latent period


  time interval between exposure and the effect or detection
• mutation effect


  abnormal growth or development due to radiation causing a genetic change
• types of radiation exposure that will damage body cells

  • acute radiation exposure
  • chronic radiation exposure
• acute radiation exposure


  radiation occurring from a massive short-term ionizing dose, such as an accidental exposure or explosion of radiation material
• chronic radiation exposure

  accumulated radiation cell damage from continual or frequent small exposures absorbed over a period of time
• Roentgen (R)


  basic unit of exposure to radiation; the amount of X-radiation or gamma radiation needed to ionize 1 cc of air
• rad (radiation absorbed dose)


  basic unit of absorbed radiation dose equal to 100 ergs
• rem (roentgen equivalent in man)


  unit of ionizing radiation needed to produce that same biological effect as 1 roentgen
• rbe (relative biological effectiveness)


  unit of measurement used to determine amount of biological absorption effects on body tissues by different types of radiation energy