Karteikarten
Unit 3 - Image Quality
Karten in diesem Stapel (48)
- 1mAs influencesdensity
brightness
shades of black - 2kVp influencescontrast
shades of gray - 3higher kVp will producemore contrast and shades of gray
- 4short-scale contrasthigh contrast
few shades of gray
low kVp
_____________
finger, toe, femur, humerus, elbow, etc... - 5long-scale contrastlow contrast
many shades of gray
high kVp
_________________
abdomen, chest, fluoroscopy, etc.... - 6Densitythe quantity of photons reaching the IR
- 7—Insufficient Density
image appears too bright
(too many x-ray photons) - 8—Excessive Density
image appears too dark
(too few x-ray photons)
- 9Spatial ResolutionDetail
Sharpness - 10Which factors contribute to SIZE distortion?Far SID
Short OID - 11Which factors contribute to SHAPE distortion?tube angle
anatomical centering - 12What are 2 forms of distortion?distortion of size (magnification, foreshortening, elongation, etc.)
distortion of shape (centering, tube angle, tilted IR, etc.) - 13Window Levelchanges brightness
- 14if an image is too dark, you can increase brightness by ________ window levelincreasing
- 15if an image is too light, you can decrease brightness by _________ window leveldecreasing
- 16ContrastCombined result of the quality of the x-ray beam, quality of radiation, quality of the IR, and computer processing and display
- 17TRUE OR FALSE? elements of high anatomic numbers absorb radiation doseTRUE:
Ca+ in bones has a high atomic number, therefore it absorbs radiation and appears white on a radiograph - 18Subject Contrastradiation will be absorbed differently throughout the body for regions of high atomic numbers vs. regions of low atomic numbers
- 19—
- 20—
- 21A radiographic image that has a greater resolution minimizes the amount of __________ of the anatomic structural linesunsharpness
- 22Good diagnostic quality is achieved by _______ _________ and by _______ _____ .maximizing resolution
minimize distortion - 23TRUE OR FALSE? increasing the bit depth of digital pixels, will increase the shades of gray within each pixelTRUE
- 24TRUE OR FALSE? increasing the number of pixels in a matrix will decrease the image qualityFALSE
having more pixels increases potential for better contrast - 25TRUE OR FALSE? With DR, you can't overexpose the patient and have a good radiograph.FALSE.
Even if your image comes out overexposed you can postprocess the image by changing your window level and still create an acceptable radiograph without re-exposing the patient. - 26The exposure indicator provides a numeric value indicating the level of radiation exposure to the __________digital image receptor.
- 27Window level adjusts ________brightness
- 28Window width adjusts ________contrast
- 29wide window width will produce _________ and a narrow window width will produce ________low contrast
high contrast - 30Pixel Pitchdistance between two pixels where they come together in the middle
- 31Visibility of Recorded Details includes:-brightness
-density
-contrast - 32Sharpness of Recorded Details includes:- spatial resolution
- distortion - 33Brightnessamount of luminance
- 34Densityamount of blackness
- controlled by mAs - 35Contrastquality of radiation absorption within the body
- controlled by kVp - 36Low-Subject Contrast-similar tissue types
- similar shades of gray
*ABDOMEN* - 37High-Subject Contrast- varying tissue types
- varying shades of black -> gray -> white
*CHEST* - 38High contrast, with low kVp and few shades of gray describes _____ _____ contrastShort - Scale
- 39Low contrast, with high kVp and many shades of gray describes _____ ______ contrastLong - Scale
- 40Size Distortion is characterized by ______ and _______Magnification
OID/SID - 41Shape Distortion is characterized by _______ _______ and ______elongation
foreshortening
tube angle
patient positioning - 42Using a grid will ________ contrast and ________ density. Therefore, you should _______ _____ when using a gridincrease
decrease
increase mAs - 43What are 3 examples of decreasing exposure time?1. decreasing SID increases speed
2. increase mA, decrease time
3. increase kVp - 44The area of the anode surface which receives the beam of electroms from the cathode is known as _____ _____FOCAL SPOT
- 45As focal spot size decreases, _________ decreases, and ________ increasesunsharpness
recorded detail - 46Bit Depthhow the exit radiation is recorded
controls the pixel brightness - 47Matrixrows and columns of the image
- 48Pixeleach individual box in a matrix