MT Flashcards
3 planes and what they divide
coronal - A/P
sagittal - R/L
transverse - S/I
Common radiographic views
AP/PA
RAO/LAO/RPO/LPO
axial
lateral
Roentgen
unit of radiation intensity in air
coulomb/kg
Rad
radiation absorbed dose - quantity of radiation received by pt.
Rem
radiation equivalent man - quantity of radiation received by radiation worker
Gray =?
= 100 rad
Sv =?
= 100 rem
Which body substance has the least radiographic density? How would it appear?
Air. Dark.
Which body substance has the greatest radiographic density? How would it appear?
Metal/bone. Light/white.
What is attenuation?
Loss of energy of a beam of radiant energy because of absorption, scattering, and other causes as the beam propagates through a medium
How does pathology affect attenuation?
• Additive Condition
Increased Attenuation (blastic)
• Destructive Condition
Decreased Attenuation (lytic)How are attenuation and radiographic blackness related?
The more attenuation, the less blackness
Which body substance attenuates most? least?
air (least), fat, water/muscle, bone, metal (most)
What is radiographic density? What x-ray factor controls it?
amount of blackness on film.
mA controls.
(density = blackness)
When you double mA and leave everything else as is, what happens to your radiographic image?
What happens to your patient?
Image blackness increased
Patient exposure increased
When you double exposure time and leave everything else as is, what happens to your image?
What happens to your patient?
Image blackness increased
Patient exposure increased
Which will give greater radiographic density, 100 mA at 1 sec or 200 mA at 0.5 sec?
Which is more likely to have motion blur?
Same density
100 mA at 1 sec more likely to have motion blur
(Incr mA, incr speed of exposure both decr motion blur)
What Xray factor is primarily responsible for controlling contrast?
kVp
What is generally meant by improving contrast?
Increasing # of shades of gray
What is beam restriction?
reduces scatter, improves image quality and
greatly reduces patient exposure. Beam must always be restricted.
What is scatter? Good? Bad?
secondary radiation that occurs when the useful beam intercepts any object. patient is the most significant source of scatter. serves no good purpose.
How is scatter minimized?
beam restriction
What is the purpose of a radiographic grid?
Grids absorb scatter radiation as it
exits patient’s body. This reduces
radiation fog and improves contrast.
When should a radiographic grid be used?
Grids should be used with larger body
parts and higher kVp.
