Radiography, Midterm Exam

50 QUESTIONS: Ch. 2 = 3, Ch. 3 = 6, Ch. 4 = 9, Ch. 5 = 7, Ch. 6 = 5, Ch. 7 = 5, Ch. 8 = 3, Ch. 12 = 6, Ch. 13 = 3, Ch. 15 = 3

30 cards   |   Total Attempts: 188
  

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Cards In This Set

Front Back
Purpose of having proper horizontal angulation?
To have open contacts between teeth
How is the central ray supposed to be in relation to the image receptor?
Perpendicular
Which ERRORS are produced by Vertical angulation in paralleling & bitewing technique?
PARALLELING TECHNIQUE
  • Excessive = cutting off incisals/occlusals
  • Inadequate = cutting off apices
BITEWING TECHNIQUE
  • Unequal distribution
Which errors are produced by vertical angulation in bisecting technique?
  • Excessive = foreshortening
  • Inadequate = elongation
Where do you find the degrees for vertical angulation? Correct angulation for bitewings?
On tube head. +10 degrees
Which exposure factor controls wavelength? How does it affect the x-ray beam?
KVp = penetration (quality)
What is frequency?
The number of times per second that a wave rises and falls to its trough. (higher frequency = more waves)
What are the 2 types of radiation?
  1. General/bremsstrahlung - most radiation, it is stopped or slowed down by tungsten atoms
  2. Characteristic - collide with K shell e- of tungsten target
What are 4 possible ways for an x-ray beam to pass through matter?
  1. No interaction - the x-ray photon passes through an atom unchanged
  2. Coherent scattering - incoming x-ray photon causes an electron to vibrate, and radiates a new unmodified x-ray photon that is scattered
  3. Photoelectric effect - incoming x-ray photon collides w/ an orbital e- and imparts electromagnetic energy to the e- in the form of kinetic energy, causing e- to fly from its orbit (creating an ion pair)
  4. Compton scattering (60% of interactions) - incoming x-ray photon collides with an orbital e- and ejects it. But, only a part of the x-ray energy is transferred to the e-, and a new, weaker x-ray photon is formed & scattered away
What is the difference between Somatic and Genetic effect?
  1. Somatic - when change or damage occurs in the irradiated individual, not offspring.
  2. Genetic - offspring
Explain Direct and Indirect theory of radiation injury
  1. Direct (1/3) - hit DNA of a cell (critical targets), collide with important cell molecules causing ionization
  2. Indirect (2/3) - ionize water & form toxins
What examinations comprise a typical FMX?
14 PA's (anterior and posterior), 4 bitewings. Therefore, no occlusal or panoramic
Explain the 2-point contact for exposing maxillary PAs using the paralleling technique
Line up tooth and sensor parallel, central ray perpendicular, 2-point contact on Maxillary ONLY, palate and occlusals
What are some advantages of digital vs. film?
Gray scale resolution, less radiation, faster, manipulation, no darkroom
How is direct digital imaging different from film?
Immediate. Film= latent image, the x-rays strike and ionize some of the silver halide crystals on the film.