Image Production and Evaluation NOTE: QA AND QC ARE USED INTERCHANGABLY IN APPLETON AND LANGE.
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Transcript of Image Production and Evaluation NOTE: QA AND QC ARE USED INTERCHANGABLY IN APPLETON AND LANGE.
Image Production and Evaluation
NOTE: QA AND QC ARE USED INTERCHANGABLY IN APPLETON AND LANGE
Intensifying screen(ref: pg 59 Mosby, 190 Bushong) Base Reflective layer Active Layer Protective layer
Intensifying.Screen: Detail and speed Thicker the active layer: less detail and
more speed Larger the phospher:less detail and
more speed Formula: old screen
new screen
Digital Imaging
PSP CRT ADC IP CR DR FOV field of view or
how much of the patient is included in the matrix
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 Actual Effective Large angle small angle anode heel
MAMMOGRAPHY
Use very low KVP 23-28 molybdenum targets High MAS
PROCESSINGPG. 62 MOSBY,180 Bushong
DEFINE
EXIT (REMNANT RADIATION) LATENT IMAGE MANIFEST IMAGE
Magnification: FOR EVERY 1” OF OID INCREASE, SID MUST INCREASE BY 7”WALLACE PG 27-33
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
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
Focal spot size Screen speed SID OID Motion artifact
CONTRAST
KVP GRID FIELD SIZE Filtration Anatomy and pathology HIGH, SHORT LOW, LONG
CHARACTERISTIC/H&D CURVE PG 58 MOSBY
Exposure error latitude
Contrast latitude speed of film base/fog processing
DIFFERENTIAL ABSORPTION & ATTENUATION
Difference between x-rays absorbed through photoelectric effect and those not absorbed at all.
Quantum Mottle
Mottled appearance (looking through a mist)
low mas-increase QM high speed film- increase QM
GRIDS
GRID RATIO: HEIGHT DIVIDED BY DISTANCE
AFFECT ON CONTRAST MULTIPLYING FACTOR GRID CUTOFF
FOCAL SPOT/ BLUR
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 BASE EMULSION
INTERACTIONS
CHARACTERISTIC COMPTON INFRARED CLASSICAL,
THOMSON, COHERENT
PHOTOELECTRIC BREMSTRAULING PAIR
PRODUCTION PHOTO-
DISINTEGRATION
Technique and Exposure