Test 1: lecture 5 Flashcards
Technique charts for digital radiography are simple and are based on ___
patient thickness and charts
why is it easier to get a diagnostic radiograph with DR?
wide exposure latitude (wide range you can get a good picture with different kVP and mAs)
which one is overexposed
A is underexposed
B is properly exposed
C is overexposed
example of ___
overexposure
As exposure increases, noise ___ because more photons reach the pixels in the detector
decreases
underexposure= fuzzy image
what is each line?
wide ___ virtually eliminates need for repeating radiographs based on technique problems
exposure latitude
low slope means the contrast of digital starts ___
low contrast, computer fixes it to look better
film-screen has ___ different opacities
5 (metal, bone, soft tissue/fluid, fat, air)
Typical DR systems can have up to 4096 ___ or more!
shades of gray
what happens during pre-processing ?
corrects for dead pixels and detectors non-uniform response to the xray beam
calibration mask
what happens during processing?
- Processing refers to steps taken after exposure that change the raw data in the pixels
- Processing improves contrast resolution among other things
Unsharp mask filtering
Multiscale processing
pre processing and processing are ___
altering of raw data
calibration mask- fix dead pixels
unsharp mask filtering and multiscale processing- improves contrast
post processing
- There is no changing of the raw data – steps just change how an image is displayed
- Includes steps done at the time of, or right after, exposure (in radiograph acquisition room)
- Look-up table
- Also includes steps done at a workstation, where radiographs are formally viewed for diagnostic purposes
Windowing/Leveling
____ •Includes steps done at the time of, or right after, exposure (in radiograph acquisition room) such as the look-up table
post processing
look-up table
change the grey scale value in each pixel
increase contrast
different tablets for different body regions
