IMAGE DISPLAY- WW, WL,

lower numbers assigned

black

higher numbers assigned

white

windowing

Method of manipulating CT numbers to fit the desired contrast

window width (ww) controls the

contrast

window level (wl) controls the

brightness

the range (quantity) of the CT numbers in the image that will be displayed

window width

udetermines the maximum number of shades of gray to be displayed on the CT monitor

window width

the midpoint or center of the range of CT numbers

window level

A large window width =

long grayscale

what is the maximum range of gray levels

-1000 to +1000

transition zone

ubetween the lower CT numbers as BLACK and the higher CT numbers as WHITE  will be large

narrow WW =

short transition zonezone from BLACK to WHITE

what does this image tell us

wide window width

The upper gray level value

WL + (WW/2)

The lower gray level value

WL – (WW/2)

Body scans are viewed at a window level of

0-+50 HU

what needs to be changed? why

WW, because there is not enough gray shades

is this a good body scan? why

yes, multiple shades of gray and can differentiate from different tissue

what kind of windowing is this

lung window

Lung window level of

►-500 to -750 HU

the lung parenchyma can be viewed in

low WL and a wide WW

WL AND WW? #

WL -600, WW 1500

what is the difference? and which is more disreable?

A has a wide WW and B has a narrow WW

Body scans are displayed at a WW of

350 HU to 600

what is the con when having a wider WW

lose a bit of image contrast

we want a x window width for the brain and liver

narrow

what is the window level for the brain

30 HU - 40 HU

why do we want that kind of WW for the brain

grey and white matter have very similar densities

WW of the brain

100 HU to 250 HU

To demonstrate the bony structures and trabeculae structures, we need a x WL and a x WW to get that low contrast image

higher / wide

mediastinal window width

+150 to -250 HU

why do we want that kind of WW for the liver

hepatic nodules are similar densities of the lung tissue

what changed? what is the WW?

WW level changed to 100-250 HU

bone window

soft tissue window

lung window

describe WW

narrow

describe WW

medium

describe WW

wide

what changed

narrowing WW

As the WL moves toward the higher CT numbers (white), more CT numbers with

lower values (black) are displayed

WL decreases, brightness x

increases

WL increases, brightness x

decreases

what is being changed here

WL

this has a x WL

lowS

this has a x WL

high