Image Production and Evaluation
NOTE: QA AND QC ARE USED
INTERCHANGABLY IN
APPLETON AND LANGE
Intensifying screen
(ref: pg 59 Mosby, 190 Bushong)
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Base
Reflective layer
Active Layer
Protective layer
Intensifying.Screen: Detail and
speed
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Thicker the active layer: less detail and
more speed
Larger the phospher:less detail and
more speed
Formula: old screen
new screen
Digital Imaging
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PSP
CRT
ADC
IP
CR
DR
FOV field of view or
how much of the patient
is included in the matrix
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Matrix-rows and
columns of pixels (512
x512)
Pixel size
– As matrix increase, pixel
size decreases
– As FOV increases, pixel
size increases
– As pixel size increases,
resolutions decreases
TARGET ANGLE
LINE FOCUS PRINCIPLE
PG. 40 i-n, Mosby
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Actual
Effective
Large angle
small angle
anode heel
MAMMOGRAPHY
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Use very low KVP 23-28
molybdenum targets
High MAS
PROCESSING
PG. 62 MOSBY,180 Bushong
DEFINE
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EXIT (REMNANT RADIATION)
LATENT IMAGE
MANIFEST IMAGE
Magnification: FOR EVERY 1” OF OID
INCREASE, SID MUST INCREASE BY 7”
WALLACE PG 27-33
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Mag. Factor - SID
SOD
SOD ---SID - OID
IMAGE SIZE -image = SID
object SOD
% OF MAG- OID
SOD X 100
#s 25,45 57,87,93
DENSITY
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OD or Logarithm of opacity
Ratio of amount of light incident on film to the amount of light
transmitted thru film (Mosby, pg. 53)
Controlling factors
–
–
–
–
–
–
–
–
–
mAs
kVP
Distance
Film/screen
Grids
Collimation
Anatomy/pathology
Anode Heel
Filtration
Detail
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Focal spot size
Screen speed
SID
OID
Motion artifact
CONTRAST
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KVP
GRID
FIELD SIZE
Filtration
Anatomy and pathology
HIGH, SHORT
LOW, LONG
CHARACTERISTIC/H&D
CURVE PG 58 MOSBY
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Exposure error
latitude
Contrast latitude
speed of film
base/fog
processing
DIFFERENTIAL ABSORPTION &
ATTENUATION
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Difference between x-rays absorbed
through photoelectric effect and those
not absorbed at all.
Quantum Mottle
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Mottled appearance (looking through a
mist)
low mas-increase QM
high speed film- increase QM
GRIDS
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GRID RATIO: HEIGHT DIVIDED BY
DISTANCE
AFFECT ON CONTRAST
MULTIPLYING FACTOR
GRID CUTOFF
FOCAL SPOT/ BLUR
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Umbra/penumbra or focal spot blur
Small FS = less
Large FS = more
Increased SID = less
decreased SID = more
increased OID = more
decreased OID = less
FILM CONSTRUCTION (Pg.
166-167 Bushong)/Cassette
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BASE
EMULSION
INTERACTIONS
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CHARACTERISTIC
COMPTON
INFRARED
CLASSICAL,
THOMSON,
COHERENT
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PHOTOELECTRIC
BREMSTRAULING
PAIR
PRODUCTION
PHOTODISINTEGRATION
Technique and Exposure