Density & Contrast (Image Quality)

Contrast

density between two adjacent areas in a radiograph

Contrast

many black and white/light areas means you have high

Density

the overall blackness of the image is referred to as the

optical density

density is also known as

kvp, mas

Density’s controlling factor and influencing factor

kvp, grid ratio, beam restrictor, development time, image receptor speed, 

factors that influence contrast:

Beam restrictors

limit the area to be irradiated (field size) → done by collimation.

Development Time

Time when the radiographic film is submerged in the processing solution

Speed

the ability of an image receptor to respond to a low x-ray exposure is measured on its sensitivity, its ___

lower

faster IR speed produce images with (lower or higher) detail

lower

faster IR speed produce images with (lower or higher) patient exposure

lower

faster IR speed produce images with (lower or higher) image resolution

higher

faster IR speed produce images with (lower or higher) quantum noise appearance

mas, kvp

exposure factors of density:

higher

higher mAs leads to increased radiation exposure and (higher or lower) density

higher

higher kvp increases the penetration of the x-ray beam, resulting in (higher or lower) density

thickness and density of the subject, atomic number of the subject

subject factors of density:

denser

(denser or thin) tissue absorb more radiation, resulting in lower density

lower

thicker tissues absorb more radiation, resulting in (higher or lower) density

higher

tissues with (higher or lower) atomic number (e.g. bones) lowers density

film speed, processing condition, grid use, distance

film/receptor factors:

faster/higher sensitivity

(faster/higher sensitivity or lower) receptors produce higher density

higher

faster or higher sensitivity receptors produce (higher or lower) density

development time, temperature, and chemicals

what are the processing conditions that can affect the final density:

increases

longer time, higher temperature, stronger chemicals, density (decreases or increases)

grid use

reduces scatter radiation, improving (density or contrast) but reducing (density or contrast)

increasing

increasing or decreasing the SID decreasing density due to beam divergence