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19 Cards in this Set
- Front
- Back
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WINDOW WIDTH
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ABSORPTION MEASUREMENT RANGE IN HU. MAX. # SHADES OF GRAY THAT CAN BE DISPLAYED ON MONITOR.
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WINDOW LEVEL
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CENTER OF RANGE OF CT #'S AND CAN BE POSITIONED ANYWHERE ON WW.
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CT # FOR BONE
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+1000
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CT # FOR AIR
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-1000
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CT # FOR WATER
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0
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5 THINGS THAT AFFECT IMAGE QUALITY
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SPATIAL RESOL., CONTRAST RESOL.,NOISE, RAD DOSE, IMAGE ARTIFACTS
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SPATIAL RESOLUTION
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DEGREE OF BLURRING ON IMAGE. MEASURE OF ABILITY TO DISCRIMINATE OBJECTS OF VARYING DENSITY IN A SMALL DISTANCE APART AGAINST UNIFORM BACKGROUND.
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FOCAL SPOT SIZE VS SPATIAL RESOL.
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FSS INCREASES, SR DECREASES. DETAILS IN OBJECT ARE SPREAD OUT OVER SEVERAL DETECTORS.
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APERTURE SIZE
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WIDTH OF APERTURE AT DETECTOR. HIGH SP WITH SMALL APERTURES
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PARTIAL VOL. EFFECT
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GETTING AN INCORRECT CT # (4MM OBJECT W/ SLICE THICKNESS OF 10MM SPREAD THE 4MM OVER ENTIRE SLICE THICKNESS)
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# OF PROJECTIONS VS. SP
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# OF PROJ INCREASES, SR INCREASES (MORE DATA FOR IMAGE RECON)
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IMAGE RECONSTRUCTION INVOLVES 2 MATH PROCEDURES
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CONVOLUTION AND BACK PROJECTION
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CONVOLUTION (KERNEL)
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AFFECTS APPEARANCE OF IMAGE STRUCTURES. HIGH-PASS FILTER.
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PIXEL SIZE =
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FOV/MATRIX SIZE
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LOW CONTRAST RESOLUTION
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ABILITY OF CT UNIT TO DEMONSTRATE SMALL CHANGES IN TISSUE CONTRAST.
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FACTORS AFFECTING LOW CONTRAST RESOLUTION
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PHOTON FLUX, SLICE THICKNESS, PT SIZE, DETECTOR SENSITIVITY, RECON ALGORITHM, IMAGE DISPLAY, IMAGE RECORDING, QUANTUM NOISE
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SOURCES OF NOISE
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QUANTUM NOISE(# OF DETECTED PHOTONS), MATRIX SIZE, SLICE THICKNESS, ALGORITHM, ELECTRONIC NOISE (DETECTOR ELECTRONICS), SCATTERED RADIATION, OBJECT SIZE
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TYPES OF IMAGE ARTIFACTS
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STREAKS, SHADING, RINGS AND BANDS
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RECORD PT DOSE
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IONIZATION CHAMBER (CTDI)
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