all things contrast :)

Question 1

what is subject contrast?

Answer 1

is the degree of density difference
between two areas on a radiograph.
● Ex: Liver vs. Lung
Contrast makes it easier to distinguish features of
interest, such as defects, from the surrounding area.
Described as Gray Scales:
● Short Scale of Contrast (Short Gray Scale)
○ High Contrast
● Long Scale of Contrast (Long Gray Scale)
○ Low Contrast

Question 2

What is digital image contrast

Answer 2

is controlled by the Look-up-Table (LUT)!!!!!
The LUT is a processing algorithm built
into the equipment that the
technologist does NOT control.

NOT controlled by kVp

Question 3

short scale of contrast is what?

Answer 3

-Short scale radiographs have only a few shades of gray. -They are mostly black and white in appearance.
-Low kVp examinations penetrate fewer thicknesses and have only a few steps between black and white. (50-70 kVp)
-Low kVp demonstrates fine bone markings and fractures better than high kVp. Think extremity work! Small Focal Spot
Lower kVp settings use
● A long wavelength
● Lower Energy
● Lower Penetrating ability
● Less chance of scatter radiation

Considered High Contrast
“short black and white penguin likes to get high”

Question 4

long scale of contrast is what?

Answer 4

-Long scale radiographs have many shades of gray in between black and white.
-Multiple shades of gray.
-High kVp examinations penetrate thicker and more dense areas of anatomy.
High kVp is used for contrast (barium) 110 kVp.
-Large Focal Spot
High kVp settings use
● A short wavelength
● Higher Energy
● Higher Penetrating ability
● Higher chance of scatter radiation
○ Decreases image quality
○ Increases patient dose
○ Increases tech dose

-Considered Low Contrast
-think of a long grey elephant