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Ketering > PRE > Flashcards

PRE Flashcards

1
Q
  1. __________ - NUMBER PHOTONS IN BEAM
  2. __________ - BEAM PENETRABILITY / HOW MANY PHOTONS PENETRATE ANATOMY
  3. THESE TERMS DESCRIBE ___________
A
  1. QUANITY = #
  2. QUALITY = PENETRATING
  3. X-RAY BEAM
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2
Q
  1. WHAT IS X-RAY OUTPUT?
  2. WHAT AFFECTS QUALITY?
  3. WHAT AFFECTS QUANTITY?
A
  1. QUANTITY = OUTPUT, INTENSITY, EXPOSURE
  2. AFFECTED KVP AND FILTRATION
  3. MAS, KVP, DISTANCE & FILTRATION
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3
Q
  1. QUANTITY MEASURED IN:
  2. QUALITY MEASURED IN:
  3. WHAT IS INTENSITY OR EXPOSURE?
A
  1. ROENTEGENS
  2. HALF VALUE LAYER (HVL)
  3. QUANTITY
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4
Q
  1. __________ & ___________ EVALUATE QUALITY OF IMAGE RESOLUTION
  2. VISIBILITY OF DETAILS:
  3. HOW RECOGNIZABLE DETAILS ARE:
A
  1. PHOTOGRAPHIC & GEOMETRIC PROPERTIES
  2. PHOTOGRAPHIC
  3. GEOMETRIC
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5
Q
  1. PHOTOGRAPHIC PROPERTIES MEANS _____________
  2. PHOTOGRAPHIC REFERS TO __________ & __________*
  3. GEOMETRIC PROPERTIES MEANS _____________
  4. GEOMETRIC REFERS TO ________ & __________
A
  1. VISBILITY DETAIL
  2. IR EXPOSURE & CONTRAST
  3. HOW RECOGNIZABLE DETAILS ARE
  4. SPATIAL RESOLUTION & DISTORTION
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6
Q
  1. WHAT IS IR EXPOSURE?
  2. CONTROLLING FACTOR:
  3. INFLUENCING FACTORS (7)
A
  1. AMOUNT OF RADIATION REACHING IMAGE DETECTOR
  2. mAs
  3. KVP, DISTANCE, FILTRATION, ANODE HEEL EFFECT, BEAM RESTRICTION, ANATOMICAL PART & GRID
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7
Q
  1. WHEN ARE CONTROLLING FACTOR USED?
  2. HOW DO WE ASSES IMAGE QUALITY & IMPACT OF EXPOSURE REACHING IR?
  3. SPATIAL RESOLUTION IN DIGITAL CONTROLLING FACTOR:
A
  1. PRIMARY MEANS OF ADJUSTMENT
  2. LOOKING AT EI VALUES FOR ACCEPTANCE
  3. PIXEL SIZE & SMALL FOCAL SPOT SIZE
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8
Q
  1. WHAT IE EI?
    - ANOTHER TERM
  2. WHAT ARE DI VALUES?
  3. UNDER EXPOSURE = ___%
    - OVER EXPOSURE - _____%
A
  1. AMOUNT RADIATION REACHING IR
    - *NOT PATIENT DOSE **
    - S NUMBER
  2. DEVIATION INDEX
    - VARIANCE BETWEEN TARGET EI VALUE
  3. UNDER =20%
    OVER = 25%
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9
Q
  1. UNDER EXPOSURE RESULTS IN
  2. INADEQUATE EXPOSURE TO DETECTOR RESULTS IN
  3. EXTREME OVEREXPOSURE CAN RESULT IN
A
  1. UNDEREXP = NOISE
  2. INADEQU = PHOTON STARVATION
  3. EXTREME = DATA DROP (INCAPABLE OF RECOGNIZING HIGH ENERGY VALUES)
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10
Q
  1. IR EXPOSURE INCREASES WHEN:
    mAs -
    kVp -
    DISTANCE -
    FILTRATION -
    BEAM RESTRICTION -
    ANATOMICAL PART -
A

INC EXPOSURE BY:
INC. MAS
INC. KVP
DECR. DISTANCE
DECR. FILTER
INC. BEAM RESTRICTION
DEC. ANATOMICAL PART
DEC. GRID / GRID RATIO

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11
Q
  1. WHAT IS MAS & HOW DOES IT CONTROL IR EXPOSURE?
  2. mAs & IR EXPOSURE DIRECT OR INDIRECT
  3. QUANTITY AKA: (3)
  4. DOUBLE MAS = _________
    - HALVED MAS = ___________
A
  1. PRODUCT OF TUBE CURRENT (mA) & EXPOSURE TIME (s)
    - NUMBER OF ELECTRONS CROSSING TUBE FROM CATHODE TO ANODE PER SECOND
  • CONTROLS # OF XRAYS PRODUCED
  1. DIRECT : INC. MAS = INC IR EXPOSURE
  2. INTENSITY, OUTPUT & EXPOSURE RATE
  3. DBL = DBL EXP
    - HALVED = HALF EXPOSURE
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12
Q
  1. EXPLAIN RECIPROCITY LAW
  2. DOES mAs AFFECT CONTRAST?
    • 100 mA × ____s = 75 mAs
      - 300 mA × ____s = 15 mAs
      - ____mA × 300 ms = 60 mAs
      - ____ mA × 150 ms = 75 mAs
A
  1. IR EXPOSURE REMAINS SAME AS LONG AS mAs VALUES CONSTANT REGARDLESS OF mA AND TIME COMBINATION
  2. NO !!
  3. 0.75 s
    - 0.05 s
    - 200 mA
    - 500 mA
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13
Q
  1. kVp MEASURES:
  2. HOW DOES IT AFFECT IR EXPOSURE?
  3. WHAT ELSE DOES kVp CONTROL?
A
  1. MAXIMUM ELECTRICAL POTENTIAL ACROSS X-RAY TUBE
  2. CONTROLS ENERGY THEREFORE SPEED/FORCE OF ELECTRONS STRIKING TARGET
  3. PENETRABILITY (QUALITY) OF BEAM, SUBJECT CONTRAST & SCATTER
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14
Q
  1. INCREASING kVp = _______ IR EXPOSURE
  2. IS kVp EVER DOUBLED?
  3. HOW TO USE kVp TO CHANGE IR EXPOSURE?
A
  1. INC = INC EXP
  2. NO, USE 15% RULE
  3. 15% RULE
    - INCREASE 15% = DBL EXPOSURE
    - DECREASE 15% = HALVES EXPOSURE
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15
Q
  1. 15% RULE AFFECTS _________ (ALWAYS) & _________ (ONLY IF NO CHANGE TO mAs TO COMPENSATE)
  2. DECREASING KVP = _______ PATIENT DOSE
    - _________ MAS = INCREASED PT DOSE
  3. Calculate 15% increase in kVp, if original exposure was 75kVp @ 10mAs.
    - A. HOW IS IR EXPOSURE CHANGED?
    - B. SUBJECT CONTRAST?
A
  1. SUBJECT CONTRAST
    - IR EXPOSURE
  2. DECR. KVP = INC PT DOSE
    - INCR. MAS = INCR PT DOSE
  3. 86 KVP
    75 x 15% (.15) = 11.25
    75 + 11.25 = 86

-A. IR EXP DOUBLED
- B. CONTRAST DECREASED

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16
Q
  1. HOW CAN MAINTAIN EXPOSURE LEVEL WHEN INCREASING KVP 15%
  2. A radiograph of the elbow is produced using 4 mAs at 60 kVp. What kVp would be required to halve the exposure to the IR?
A
  1. mAs ADJUSTED
    - DEC. 15% = DOUBLE mAs
    - INCR. 15% = HALF mAs
  2. 15% of 60 kVp = 60 x 0.15 = 9 kVp
    60 kVp – 9 kVp = 51 kVp
    - REDUCING FROM 60 TO 51 WILL HALF EXPOSURE TO IR
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17
Q
  1. WHAT HAPPENS WITH EXPOSURE WHEN SID INCREASES?
    - RELATION?
  2. WHAT HAPPENS TO EXPOSURE / INTENSITY WHEN DISTANCE DOUBLED?
  3. EXPLAIN INVERSE SQUARE LAW & FORMULA
  4. EXPLAIN EXPOSURE MAINTENANCE & FORMULA
A
  1. EXPOSURE DECREASES
    - INVERSE / INDIRECT
  2. EXPOSURE DECREASES 4X
  3. QUANTITY OF XRAY PHOTONS INVERSELY PROPORTIONAL TO SQUARE OF DISTANCE
  4. WHEN mAs NEED BE ADJUSTED TO MAINTAIN IR EXPOSURE WHEN SID CHANGES
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18
Q
  1. An acceptable chest image results from an exposure taken using 8 mAs at 110 kVp at 72-inch SID. A second image must be taken supine at 36-inch SID. What new mAs will be required to maintain the same exposure at 36” SID?
  2. When changing your SID from 72” to 56”
    a. decrease your kVp by 15 percent.
    b. decrease your mAs by 50 percent.
    c. increase the mAs by a factor of 4.
    d. increase the kVp by 15 percent.

3.In the event of making a single exposure that is critical to the exam success,
most experienced technologists will

a. use slightly less mAs than necessary to prevent overexposure.
b. overexpose the IR slightly.
c. provide enough exposure to create an adequate histogram.
d. both b and c.

A
  1. Distance decreased by half – mAs must decrease 4 times (1/4 ORIGINAL)

Answer: 2 mAs will be required to use at 36” SID

  1. b. decrease your mAs by 50 percent.
    - ANYTIME 40 TO 56 = INCREASE MAS 50% OR 72 TO 56 = DECREASE MAS 50%
  2. B. & C
    - OVEREXPOSURE BETTER IN DIGITAL & PROVIDE ENOUGH EXPOSURE FOR ADEQUATE HISTOGRAM
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19
Q
  1. FILTRATION ELIMINATES ________
    - RELATION WITH IR EXPOSURE:
  2. ANODE HEEL EFFECT IR EXPOSURE GREATER AT ________ END
    - A. SIGNIFICANT WITH _______ ANODE
  3. HOW DOES BEAM COLLIMATION EFFECT IR EXPOSURE?
    - EXPLAIN!!
    - RELATION:
A
  1. ELIMINATES LOW ENERGY PHOTONS
    - INC FILTER = DECR. IR EXPOSURE
  2. GREATER AT CATHODE
    - A. SMALL ANODE ANGLE ( SMALL ANGLE = MORE ANODE HEEL EFFECT)
  3. COLLIMATING REDUCES SIZE OF PRIME BEAM & REDUCING SCATTER
    - REDUCING TOTAL # PHOTONS REACHING IR = LESS IR EXPOSURE
    - INC COLLIMATION = DECR. IR EXPOSURE
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20
Q
  1. HOW DO GRIDS AFFECT IR EXPOSURE?
    - EXPLAIN & RELATION
  2. ANATOMICAL PART REFERS TO: (5)
  3. HOW DO ANATOMICAL PARTS AFFECT IR EXPOSURE?
    - EXPLAIN & RELATION
A
  1. GRIDS ABSORB SCATTER & PHOTONS
    - DECREASING PHOTONS TO IR
    INCR. GRID RATIO = INCR. LEAD CONTENT = DECR. IR EXPOSURE
  2. TISSUE THICKNESS/DENSITY, ANATOMIC #, PATHOLOGICAL CONDITION, CASTS & CONTRAST
  3. INCREASE THICKNESS - INCREASES ATTENUATION DEPENDING ON THICKNESS / TYPE OF TISSUE BEING IMAGED
    - THIS WILL DECREASE IR EXPOSURE
    - INC. THICKNESS = DECR. EXPOSURE
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21
Q
  1. ATTENUATION FROM LEAST TO MOST:
    MUSCLE, AIR, BONE & FAT
  2. ADDITIVE DISEASES REQUIRE:
  3. DESTRUCTIVE DISEASES REQUIRE:
A
  1. AIR - FAT - MUSCLE - BONE
  2. INCREASE TECHNIQUE
  3. DECREASE TECHNIQUE
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22
Q

ADDITIVE CONDITIONS:

A

Ascites

Paget’s disease

Pneumonia

Atelectasis

Congestive heart failure

Edema

Tumors

Pleural effusion

Tuberculosis

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23
Q

EXAMPLES OF DESTRUCTIVE CONDITIONS

A

Osteoporosis

Osteomalacia (rickets)

Pneumothorax

Bowel obstruction

Emphysema

Degenerative arthritis

Atrophy

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24
Q
  1. CONTRAST REFERS TO ________
  2. WHAT IS RADIOGRAPHIC CONTRAST?
  3. WHAT IS CONTRAST RESOLUTION?
    - DEPENDENT ON:
A
  1. GRAYSCALE
  2. DIFFERENCE BETWEEN ADJACENT IR EXPOSURES (DENSITIES)
  3. ABILITY OF DIGITAL SYSTEM TO DISPLAY SUBTLE CHANGES IN SHADES OF GRAY
    - RELATED TO PIXEL DEPTH
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25
Q
  1. WHEN DIFFERENCE BETWEEN ADJACENT IR EXPOSURES ARE GREAT, IMAGE HAS _____ CONTRAST = ______ GRAYSCALE & _____ SHADES OF GRAY
  2. WHEN DIFFERENCE BETWEEN ADJACENT IR EXPOSURES ARE MINIMAL, IMAGE HAS _____ CONTRAST = ______ GRAYSCALE & _____ SHADES OF GRAY
  3. CONTROLLING FACTOR OF CONTRAST RESOLUTION:
    - A. POSTPROCESSING ADJUSTMENT:
A
  1. GREAT = HIGH CONTRAST = SHORT SCALE = FEW SHADES
  2. MINIMAL = LOW CONTRAST = LONG GRAYSCALE = MANY GRAYS
  3. BIT DEPTH
    - WIDTH (INC WIDTH =
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26
Q
  1. CONTRAST/GRAYSCALE IS CONTROLLED BY _____
  2. ______ DETERMINES CONTRAST RESOLUTION/GRAYSCALE
  3. WHAT IS SUBJECT CONTRAST?
  4. WHAT CONTROLS SUBJECT CONTRAST?
A
  1. LUT & POST PROCESSING WINDOW
  2. BIT DEPTH
  3. RANGE OF DIFFERENCE INTENSITIES OF X-RAY BEAM AFTER ATTENUATED BY PATIENT
  4. kVp & TISSUE THICKNESS/TYPE
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27
Q
  1. ATTENUATION IS:
  2. HOW DOES kVp CONTROL SUBJECT CONTRAST
  3. HIGH KVP = ______ CONTRAST = ______ SCALE (____ SHADES)
  4. LOW KVP = ______ CONTRAST = ______ SCALE (____ SHADES)
A
  1. REDUCTION IN XXRAY INTENSITY AS RESULT OF ABSORPTION & SCATTER
  2. KVP CONTROLS ENERGY & PENETRATING POWER OF BEAM
    - KVP ALSO CONTROLS SCATTER

INC. KVP = INC COMPTON INTERACTION = INC. SCATTER = LONGER GRAYSCALE = LOWER CONTRAST

  1. HIGH KVP = LOW CONTRAST = LONG SCALE / LOTS GRAYS
  2. LOW KVP = HIGH CONTRAST = SHORT SCALE / LESS GRAYS
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28
Q
  1. HIGH CONTRAST DIRECTLY RELATED TO ________ INTERACTION
  2. LOW CONTRAST DIRECTLY RELATED TO ________ INTERACTION
  3. SUBJECT CONTRAST ALSO AFFECTED BY ________, ______ & _________
A
  1. HIGH = PHOTOELECTRIC
  2. LOW = COMPTON INTERACTION
  3. THICKNESS, TISSUE DENSITY & ATOMIC NUMBER
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29
Q
  1. THICKNESS OF BODY PART = ______ SUBJECT CONTRAST
  2. HIGHER ATOMIC # = _______ SUBJECT CONTRAST
  3. When there is great difference in the atomic numbers of adjacent material:
  4. When there is little difference in the atomic numbers of adjacent materials:
A
  1. THICK = DECREASED
  2. HIGHER = INCREASED
  3. When there is great difference in the atomic numbers of adjacent materials 🡪
    subject contrast increases (bone vs soft tissue)
  4. When there is little difference in the atomic numbers of adjacent materials 🡪
    subject contrast decreases (ex: soft tissue in abdomen)
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30
Q
  1. WE USE HIGH KVP IN DR BECAUSE:
  2. CONTRAST RESOLUTION IN DR GREAT AFFECTED BY:
  3. WHY IS TIGHT COLLIMATION IMPORTANT
  4. IS THERE A NUMERICAL INDICATOR TO QUANTIFY CONTRAST?
A
  1. DECREASE PT DOSE
  2. AMOUNT SCTATER
    - DR MORE SENSITIVE TO DR
  3. CONTROL SCATTER
  4. NO
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31
Q

CONTRAST/LUT
1. CONTROLLED BY:
2. DETERMINED BY:

SUBJECT CONTRAST
3. CONTROLLING FACTOR
4. ALSO INFLUENCED BY:

A
  1. LUT
  2. BIT DEPTH
  3. KVP
    PART THICKNESS, DENSITY & ATOMIC #
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32
Q
  1. Which of the following groups of exposure factors will produce the
    longest grayscale?
    (A) 200 mA, 1/20 second, 70 kV, 12:1 grid
    (B) 500 mA, 0.02 second, 80 kV, 16:1 grid
    (C) 300 mA, 30 msec, 90 kV, 8:1 grid
    (D) 600 mA, 15 msec, 70 kV, 8:1 grid
A
  1. (C) 300 mA, 30 msec, 90 kV, 8:1 grid
  • Long scale = lots of shades of gray = low contrast => more scatter => high kV
  • Lower grid ratio = Lower contrast
  • HIGH KVP & LOW GRID RATIO = LONG GRAYSCALE
  • IGNORE MAS B/C DOESNT AFFECT CONTRAST
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33
Q
  1. DEFINE SPATIAL RESOLUTION:
  2. OTHER TERMS FOR SPATIAL RESOLUTION (5)
  3. FIDELITY REFERS TO ________
    - XRAY FIDELTIY:
A
  1. ABILITY PERCEIVE SMALL STRUCTURES ON IMAGE AS SEPARATE AND DISTINCT
    - GEOMETRIC SHARPNESS OR ACCURACY OF STRUCTURAL LINES
  2. RECORDED DETAIL, DETAIL , DEFINITION, SHARPNESS & RESOLUTION
  3. TRUENESS OF IMAGE
    - XRAY ALWAY HAVE LESS RECORDED DETAIL THAN OBJECT ITSELF
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34
Q
  1. POOR SPATIAL RESOLUTION IS CAUSED BY:
  2. GEOMETRIC UNSHARPNESS IS CALLED _____
    - SHARPNESS CALLED _____
  3. FACTORS OF SPATIAL RESOLUTION:
A
  1. UNACCEPTABLE LEVEL OF PENUMBRA
  2. PENUMBRA (GEOMETRIC UNSHARPNESS)
    - UMBRA
  3. PIXEL/MATRIX SIZE
    - FOCAL SPOT SIZE, OID, SID, MOTION, PATIENT THICKNESS & MAGNIFCATION
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35
Q

SPATIAL RESOLUTION INCREASED BY:
- PIXEL/MATRIX SIZE:
- FOCAL SPOT SIZE:
- OID:
- SID:
- MOTION:
- PATIENT THICKNESS:
- MAGNIFICATION:

A
  • PIXEL/MATRIX SIZE: DECR. PIXEL / INCR. MATRIX
  • FOCAL SPOT SIZE: DECR. FSS (SMALL FSS)
  • OID: DECR. OID
  • SID: INCR. SID
  • MOTION: NO MOTION
  • PATIENT THICKNESS: DECR. THICKNESS
  • MAGNIFICATION: DECR. MAG
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36
Q
  1. HOW DOES FOCAL SPOT SIZE AFFECT SPATIAL RESOLUTION?
  2. HOW DOES OID AFFECT SPATIAL RESOLUTION?
  3. HOW DOES SID AFFECT SPATIAL RESOLUTION?
  4. DESIRED FOR EACH:
A
  1. DECREASE FOCAL SPOT SIZE = DECREASES PENUMBRA = INCREASES SPATIAL RESOLUTION
  2. DECR. OID = DECR. PENUMBRA (BC MAGNIFICATION DECREASEED) = INCR. SPATIAL RES.
  3. INCR. SID = DECR PENUMBRA / MAGNIFICATION = INCR. SPATIAL RES.
  4. SMALL FOCAL SPOT, LARGE MATRIX
    - SMALL OID
    - LARGE SIDE
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37
Q
  1. SPATIAL RESOLUTION MEASURED IN
  2. HIGH SPATIAL FREQUENCY = ______ SPATIAL RESOLUTION
  3. WHAT IS MTF?
  4. DOES NOISE MEASURE SPATIAL RES?
A
  1. LINE PAIR PER MILLIMETER (LP / MM)
    - LINE PAIR = ONE LINE & ONE INTERSPACE
  2. HIGH SPATIAL FREW = HIGH SPATIAL RES.
  3. MODULAR TRANSFER FUNCTION
    - NEVER 100& / 1 B/C NEVER PERFECT
  4. YES
38
Q
  1. HIGH SPATIAL FREQUENCY REPRESENTS PAIRS OF LINES THAT ARE _________
  2. WHAT IS NOISE?
  3. TYPES:
A
  1. CLOSE TOGETHER
  2. ANYTHING INTERFERES WITH IMAGE & DIMINISHES VISIBILITY OF DETAIL
  3. SCATTER, QUANTUM, ARTIFACTS & SYSTEM OISE
39
Q
  1. RELATION BETWEEN SNR & SCATTER?
  2. WHAT AFFECTS NOISE / SNR?
  3. SNR HIGHEST WITH ______ GRID
  4. DOES SOD AFFECT SPATIAL RESOLUTION?
    - WHAT IS DESIRED?
A
  1. INC SCATTER = DECR. SNR
  2. ANYTHING PREVENT PHOTONS FROM REACHING IR WILL CAUSE NOISE & LOW SNR
  3. NO GRID / LOW GRID
  4. YES
    - LONG SOD DESIRED
39
Q
  1. FOCAL SPOT SIZE CAPABILITIES:
  2. WHAT IS DISTORTION?
  3. WHAT TYPES OF SIZE DISTORTION IN XRAY?
  4. WHAT ARE TYPES OF SHAPE DISTORTION IN XRAY?
A
  1. CAN ONLY IMAGE STRUCTURE LARGER THAN THEIR SIZE
    (.3 mm can not visualize .1 mm structure)
  2. MISREPRESENTATION OF SIZE & SHAPE OF STRUCTURES
  3. SIZE = MAGNIFICATION
  4. SHAPE = ELONGATION & FORESHORTENING
40
Q
  1. WHY DOES MAGNIFICATION OCCUR?
  2. WHAT TYPE OF DISTORTION IS IT?
  3. HOW DOES IT EFFECT SPATIAL RES?
  4. WHEN DOES ELONGATION OCCUR?
  5. WHEN DOES FORESHORTENING OCCUR?
  6. WHAT TYPE OF DISTORTION ARE THESE?
A
  1. DIVERGENCE OF XRAY BEAM (SID & OID)
  2. SIZE DISTORT.
  3. DECREASES SPATIAL RES.
  4. ELONGATED = TUBE/CR OR IR MISALIGNED
  5. FORESHORTENING = PART INCLINED
  6. SHAPE DISTORTION
41
Q
  1. HOW DOES SID AFFECT MAGNIFICATION?
  2. HOW DOES OID?
  3. WHAT ABOUT SOD?
  4. RULE OF THUMB FOR OID/SID?
  5. WHAT PATIENT FACTORS AFFECT MAGNIFICATION?
A
  1. DECREASED MAGNIFICATION BY INCREASING SID
  2. DECREASED MAGNIFICATION BY DECREASING OID
  3. SMALLER SOD = GREATER MAG = INCREASED ENTRANCE SKIN EXPOSURE
  4. DECR. OID BY INCR. SID
    EVERY 1IN OID = INCR. SID BY 7in
  5. PATIENT THICKNESS & POSITION OF ANATOMIA STRUCTURES IN BODY
42
Q
  1. MISALIGNED CR TO IR, CR TO PART, OR IR TO PART =
  2. ANGULATION OF CR RESULT IN=

3, IF PART NOT PARALLEL TO IR (IF PART ANGLED / AWAY) =

A
  1. ELONGATION
  2. SHAPE DISTORTION (ELONGATED OR FORESHORTENED)
  3. FORESHORTENING
43
Q
  1. FORMULA FOR MAGNIFICATION
A
  1. M = SID / SOD
    OR: M = IS / OS

IMAGE SIZE ALWAYS LARGER

44
Q
  1. WHEN X-RAYS INTERACT WITH PATIENTS THEY:
  2. SCATTER PRODUCED BY _________,
    - INTERACTION INCREASES WITH _____ KVP.
    - HIGH KVP _______ SUBJECT CONTRAST
  3. WHAT FACTORS CONTRIBUTE TO INCREASE OF SCATTER?
A
  1. SCATTER, ABSORB, TRANSMIT W/O INTERACTION OR SCATTER WITHIN PATIENT
  2. COMPTON
    - HIGHER KVP / INCREASED
    - HIGH KVP DECREASE SUBJ. CONTRAST
  3. KVP, PATIENT THICK, COLLIMATION & ATOMIC NUMBER
45
Q
  1. HOW CAN WE CONTROL SCATTER?(4)
  2. HOW DOES SCATTER AFFECT CONTRAST AND IR EXPOSURE?
  3. MAIN FUNCTIONS OF GRID (2)
A
  1. LOWER KVP
    - INCREASED COLLIMATION (DEC. FIELD SIZE)
    - COMPRESSED ANATOMY
    - BREAM RESTRICTORS & GRIDS (OR AIR GAP)
  2. INCR. SCATTER = DECR. CONTRAST = INCR. IR EXPOSURE
  3. SCATTER CLEANUP & INCREASE / IMPROVE CONTRAST
46
Q
  1. GRIDS ARE MADE OF:
  2. GRID RATIO:
  3. If the lead strips are 3mm high and are separated by an interspace of 0.25 mm, what is the grid ratio?
A
  1. ALTERNATING RADIOPAQUE GRID STRIPS (LEAD) & RADIOLUCENT INTERSPACE MATERIAL (ALUMINUM)
  2. HEIGH LEAD STRIP TO WIDTH OF INTERSPACE
  3. GR = 3 / .25 = 12:1
47
Q
  1. IR EXPOSURE ______ WHEN GRIDS ARE USED.
    - WHAT NEEDS TO BE ADJUSTED?
  2. GRID CONVERSION FORMULA:
  3. GRID CONVERSIONS FOR:
    - NONE:
    - 5:1
    - 6:1
    - 8:1
    - 10:1
    - 12:1
    - 16:1
A
  1. IR EXPOSURE DECREASES
    - MAY NEED TO INCR. mAs TO MAINTAIN EXPOSURE TO IR
  2. MAS1 / MAS2 = GCF1 / GCF2
    • NONE: 1
      - 5:1 = 2
      - 6:1 = 3
      - 8:1 = 4
      - 10:1 = 5
      - 12:1 = 5
      - 16:1 = 6
48
Q
  1. WHEN ARE GRIDS USED?
  2. WHAT HAPPENS TO PATIENT DOSE WHEN GRIDS USED?
  3. An 8:1 grid is used with 20 mAs at 85 kV and produces a sufficient exposure. If exposure is to be repeated using a 12:1 grid, what mAs is required?
A
  1. BODY THICKER THAN 10 cm
    - kVp HIGHER 60
  2. INCREASED
  3. 25 mAs
49
Q
  1. COMMON FOCUS GRID ERROR:
  2. WHAT IS OFF LEVEL GRID ERROR?
  3. WHAT IS OFF CENTER GRID ERROR?
  4. WHAT IS OFF FOCUS GRID ERROR?
  5. WHAT IS UPSIDE DOWN GRID ERROR?
A
  1. TUBE MUST BE CENTERED TO GRID & ALIGNED CORRECT DISTANCE (FOCUS GRID HAS TUBE SIDE)
      1. IMAGE:
50
Q
  1. IMPROPER ALIGNMENT BETWEEN X-RAY & GRID RESULT IN:
  2. WHAT IS CUT OFF?
  3. WHAT ERROR IS IMAGED?
A
  1. CUTOFF
  2. DECREASE IN NUMBER OF PHOTONS REACH IR B/C MISALIGNMENT OF GRID
  3. UPSIDE DOWN GRID (SEVERE GRID CUTOFF / LOSS EXPOSURE ALONG PERIPHERY/EDGE OF IMAGE)
51
Q
  1. GRID REPLACEMENT SOFTWARE IS:
    - INTENDED FOR:
    - NOT INTENDED FOR:
  2. GRID SUPPRESSION SOFTWARE IS:
  3. WHAT DOES AIR GAP & GRIDS DO?
A
  1. PROGRAM DESIGNED PRODUCE GRID LIKE IMAGE W/O GRID
    - INTENDED TO DECR. DOSE, IMPROVE IMAGE QUALITY & EFFICIENCY
    - NOT INTENDED FOR ALL GRID EXAMS
  2. REMOVES GRID LINES FROM IMAGE TAKEN W GRID
  3. DECREASE SCATTER, INCREASE CONTRAST & REDUCE IR EXPOSURE
52
Q
  1. HIGH GRID RATIOS HAVE _____ CENTERING LATITUDE WHILE LOW GRID RATIOS HAVE _______ CENTERING LATITUDE
  2. ANGULING ACROSS LONG AXIS OF LINEAR GRID CAUSE:
  3. FOCUS GRID VS PARALLEL GRID
A
  1. HIGH = LESS CENTERING LATITUDE / NEED PRECISE
    LOW = MORE CENTERING LATITUDE
  2. ACROSS = HITTING LEAD = GRID CUTOFF
    - LINEAR GRID = WANT TO GO LONG AXIS / SAME WAY AS LINES PARALLEL
  3. FOCUS GRID = GRID LINES MATCH BEAM DIVERGENCE, ALIGNMENT VERY IMPORTANT
  • PARALLEL = JUST STRAIGHT LINES
53
Q
  1. WHY ARE EXPOSURE SYSTEMS IMPORTANT?
  2. WHAT TYPE OF TECHNIQUE SYSTEMS ARE THERE?
  3. WHEN DO TECHNIQUE SYSTEMS FUNCTION BEST?
A
  1. PROVIDE METHOD OF CONSISTENT QUALITY IMAGE PRODUCTION
    - ASSURE CORRECT EXPOSURE FACTORS SELECTED
    - DELIVER EI WITHIN ACCEPTABLE RANGE
  2. FIXED KVP
    - VARIABLE KVP
    - ANATOMICALLY PROGRAMMED RAD. SYSTEM (APR)
  3. WHEN LARGE NUMBER VARIABLES CAN BE HELD CONSTANT WHILE SINGLE FACTOR PERMITTED TO VARY
54
Q
  1. EXPLAIN FIXED KVP SYSTEM
    - ALSO KNOWN AS:
  2. WHAT ARE DISADVANTAGE OF FIXED?
  3. WHAT ARE ADVANTAGES OF FIXED?
A
  1. SYSTEM USES FIXED KVP (OPTIMAL/MAX/HIGH) FOR EACH BODY PART AND VARIABLE MAS
    - mAs CHART SYSTEM
  2. LOWER CONTRAST & MORE SCATTER
  3. DECREASED PT DOSE (KVP ALWAYS HIGH)
    - INCR. CONSISTENCY (KV CONSTANT)
    - LOWERED TUBE HEATING (B/C MAS DECREASED)
    - DECREASED TIME (REDUCE MOTION)
55
Q
  1. HOW DOES FIXED KVP SYSTEM WORK (MAS/KVP)?
  2. IS FIXED OR VARIABLE MORE USED?
    - WHICH BETTER IN DIGITAL?
  3. IS KVP HIGHER IN FIXED OR VARIABLE?
A
  1. MAS IS ADJUSTED AND VARIES ACCORDING TO THICKNESS OF PATIENT
    - EVERY 5CM THICKNESS = DOUBLE OR HALF mAs
  2. FIXED USED MORE
    - FIXED BETTER FOR DIGITAL
  3. HIGHER IN FIXED
56
Q
  1. EXPLAIN VARIABLE KVP SYSTEM
    - ALSO KNOWN AS:
  2. WHAT ARE DISADVANTAGE OF VARIABLE?
  3. WHAT ARE ADVANTAGES OF VARIABLE?
A
  1. USES FIXED mAs AND kVp VARIES ACCORDING TO THICKNESS & PART
    - FIXED mAs SYSTEM
  2. HIGHER PATIENT DOSE
    - LESS CONSISTENCY IN CONTRAST
  3. ASSURES ADEQUATE PENETRATION OF PART
57
Q
  1. HOW DOES VARIABLE SYSTEM WORK (MAS/KVP)
  2. MAIN DIFFERENCE BETWEEN FIXED & VARIABLE:
  3. CONSOLE HAS _____ SYSTEM
A
  1. KVP DETERMINED BY CALIPER MEASURE THICKNESS
    - ADJUST KVP 2 per cm PART THICKNESS
  2. FIXED = HIGH KVP, MAS ADJUSTED
    - VARIABLE = FIXED MAS, KVP ADJUSTED
  3. CONSOLE = FIXED
58
Q
  1. EXPLAIN APR SYSTEM:
  2. WHAT IS USED WITH APR?
  3. APR SHOULD BE USED AS ______ & YOU MUST _______________
A
  1. PRE - PROGRAMMED TECHNIQUES IN COMPUTER BASED OFF CHART
  2. AEC
  3. STARTING POINT AND ADJUSTED AS NEEDED FOR BEST QUALITY
59
Q
  1. RELATION BETWEEN SNR & SCATTER?
  2. WHAT AFFECTS NOISE / SNR?
  3. SNR HIGHEST WITH ______ GRID
  4. DOES SOD AFFECT SPATIAL RESOLUTION?
    - WHAT IS DESIRED?
A
  1. INC SCATTER = DECR. SNR
  2. ANYTHING PREVENT PHOTONS FROM REACHING IR WILL CAUSE NOISE & LOW SNR
  3. NO GRID / LOW GRID
  4. YES
    - LONG SOD DESIRED
60
Q
  1. WHAT IS AEC?
  2. WHAT DOES IT CONTROL?
  3. WHAT IS IT REFERRED TO AS?
  4. WHY AEC USED?
A
  1. SYSTEM MEASURE PRESET QUANTITY OF RADIATION REACHING IR AND TERMINATED EXPOSURE WHEN SUFFICIENT AMOUNT REACHED
  2. EXPOSURE TIME AND THEREFORE TITAL EXPOSURE
  3. PHOTOTIMING
  4. IMPROVE CONSISTENCY IN IMAGE QUALITY / INCR. REPRODUCIBILITY
61
Q
  1. PROCESS AEC:
  2. CRITICAL FACTORS OF AEC:
  3. WHICH TECHNICAL FACTOR CAN BE ADJUSTED IN AEC?
  4. FIRST GEN AEC USED:
A
  1. AIR IONIZED - ELECTRICAL CHARGE CREATED - TIMER TRIPPED - EXPOSURE TERMINATED
  2. ANATOMY POSITION OVER SELECTED DETECTOR
    - PRECISE POSITIONING
  3. MA & KVP
  4. PHOTOMULTIPLIER TUBE & PHOTODIODES
62
Q
  1. TODAY AEC USES:
  2. IONIZATION CHAMBERS LOCATED
    - MEASURED:
  3. CONFIGURATION OF AEC:
  4. TECH LOSES CONTROL OF ____ & ____ IN AEC
A
  1. IONIZATION CHAMBER
  2. ABOVE IR AND MEASURE EXPOSURE TO IR
    BETWEEN PATIENT & IR
  3. ONE CENTER CELL & 2 HIGHER CELLS TO R & L (CELLS, CHAMBERS, DETECTORS)
  4. TIME & mAs (ELIMINATE NEED SET TIME, AND AS RESULT mAs)
63
Q
  1. WHAT IS CRITICAL IN AEC?
  2. IF PATIENT HAS PNEUMONECTOMY ON RIGHT SIDE, WHICH CHAMBER SELECTED?
    - HIP BONES? ALA?
  3. HOW CAN EXPOSURE RATE BE ADJUSTED WITH AEC?
A
  1. POSITIONING
  2. LEFT ONLY (SELECT SIDE THAT HAS SOMETHING TO MEASURE, RIGHT SIDE HSA NOTHING TO MEASURE)
    - ALL 3, BUT ALA IS ONLY TOP 2
  3. DENSITY CONTROL (EXPOSURE DIALS)
64
Q
  1. DENSITY CONTROL ADJUSTS AMOUNT OF RADIATION IN INCREMENTS OF ______
    - USED WITH:
  2. WHAT SHOULDN’T DENSITY CONTROL BE USED FOR?
  3. WHAT IS ITS PURPOSE/ USED FOR?
A
  1. 25-30% (-3, -2,-1,0+1,+2,+3)
    - AEC
    - +2 = 50% INCREASED
    - -3 - 75% DECREASED
  2. NOT COMPENSATE FOR PART THICKNESS OR KVP CHANGES
  3. PROPERLY USED TO COMPENSATE WHEN POSITION OF DETECTOR CANNOT BE ADAPTED TO PART INTEREST
65
Q
  1. RELATION BETWEEN SNR & SCATTER?
  2. WHAT AFFECTS NOISE / SNR?
  3. SNR HIGHEST WITH ______ GRID
  4. DOES SOD AFFECT SPATIAL RESOLUTION?
    - WHAT IS DESIRED?
A
  1. INC SCATTER = DECR. SNR
  2. ANYTHING PREVENT PHOTONS FROM REACHING IR WILL CAUSE NOISE & LOW SNR
  3. NO GRID / LOW GRID
  4. YES
    - LONG SOD DESIRED
66
Q
  1. What is determined by the minimum length of time necessary for the AEC to respond to the radiation and for the generator to terminate the exposure?
  2. WHAT HAPPENS IF EXPOSURE TIME NEEDED FOR EXAM IS SHORTER THAN MRT OF AEC?
    - WHAT IS RULE OF THUMB?

3.CAN YOU ALWAYS USE AEC WITH SMALL BODY PARTS?

A
  1. MINIMUM RESPONSE TIME (MRT)
    - 0.001 seconds
  2. OVEREXPOSURE
    - EXPOSURE TIME NEVER SHORTER THAN MRT
  3. NO - SOME PARTS TOO SMALL COMPLETELY COVER CELL & WILL TERM EXPOSURE PREMATURE = UNDEREXPOSED
67
Q
  1. HOW DOES OVER EXPOSURE OCCUR IN AEC?
    - UNDEREXPOSURE?
  2. WHAT IS BACK-UP TIME?
  3. WHAT ARE THEY SET AT?
A
  1. OVER = EXPOSURE TIME SHORTER THAN MRT
    - UNDER - CELL NOT COVERED
  2. MAXIMUM LENGTH OF TIME X-RAY EXPOSURE WILL CONTINUE IN AEC
  3. 150% OR 1.5 TIMES EXPECTED MANUAL EXPOSURE TIME OR mAs
68
Q
  1. If the manual technique for the knee is 8 mAs , what should be the backup mAs the radiographer should set for AEC?
  2. FUNCTION OF BACKUP TIMER?
  3. WHAT OCCURS IF BACKUP TIMER IS SHORTER THAN NEEDED EXPOSURE TIME?
A
  1. 8 mAs x 1.5 = 12mAs
  2. SAFETY MECHANISM PROTECT PATIENT & TUBE
  3. UNDEREXPOSED (EXPOSURE TERMINATED TOO SOON)
69
Q

IMAGE OVEREXPOSURE
1.
2.
3.
4.
5.
6.
7.

A
  1. WRONG BUCKY ACTIVATED
  2. EXPOSURE TIME LESS MRT
  3. DENSITY CONTROL TOO HIGH (LEFT ON HIGH)
  4. MALFUNCTION
  5. INCORRECT DETECTOR CELL CONFIGURATION )ACTIVATED CELL UNDER DENSER OR THICKER TISSUE THAN AREA OF INTEREST)
  6. RADIOPAQUE ARTIFACT (OR PROTHESIS)
  7. EXTERNAL RADIOPAQUE OBJECT (LEAD SHEETS, SANDBAGS, ETC..)
70
Q
  1. BEST TO USE MANUAL TECHNIQUE WITH _________ & __________.
  2. PROBLEMS WITH AEC OCCUR WHEN _____________ & __________
A
  1. CAN’T BE POSITIONED CORRECTLY OR CONTRAST STUDY
  2. HIGH MA STATION USED
    - SMALL ANATOMICAL PARTS IMAGED
71
Q

CAUSES OF UNDEREXPOSURE

A
  1. BACKUP TIMER SHORTER THAN NEEDED EXPOSURE (LARGE PATIENT)
  2. DENSITY CONTROL TOO LOW (LEFT ON MINUS)
  3. INADEQUATE COLLIMATION (EXCESSIVE SCATTER REACHES SENSORS)
  4. INCORRECT DETECTOR CELL CONFIGURATION (ACTIVATE CELL UNDER THINNER TISSUE)
  5. DETECTOR NOT FULLY COVERED (TOO PERIPHERAL, TOO SMALL OR POOR CENTERING)
72
Q
  1. The lateral coccyx image was made using AEC but is overexposed. This is most likely a result of
    A. Incorrect selection of small focal spot
    B. Insufficient backup time
    C. Selection of the center photocell
    D. Incorrect centering of the part
A

D. INCORRECT CENTERING

Focal spot doesn’t affect contrast or IR exposure

Insufficient back up time would cause underexposure

Selection of the center photocell is appropriate for the coccyx bc
you want the anatomy in the center of the image

If the part is not centered correctly – the actual center of the part is
over thicker anatomy in this case 🡪 that causes overexposure

73
Q
  1. STRUCTURE EYE FOR VISION: (2)
    - EXPLAIN EACH
  2. WHERE IS TUBE IN TYPICAL FLURO?
    - WHERE IS IMAGE INTENSIFIER?
  3. WHATS DIFFERENT ABOUT FLURO TUBE COMPARED TO XRAY
A
  1. RODS - DARM/DIM LIGHT (SCOTOPIC)
    - CONES - DAYLIGHT (PHOTOPIC)
  2. UNDER X-RAY TUBE
    - OVER PATIENT
  3. FLURO = OPERATE LONGER PERIODS TIME
    - MUCH LOWER mA
74
Q
  1. FLURO mA RANGE:
  2. WHY IS PATIENT DOSE HIGHER IN FLURO?
  3. FIXED FLURO SOD MINIMUM:
A
  1. .5 - 5 mA
  2. LONGER EXPOSURE TIMES
  3. 15 INCHES / 38 CM
75
Q
  1. WHAT DOES IMAGE INTENSIFIER CONVERT XRAYS TO?
  2. INPUT PHOSPHOR/SCREEN
    - THIN LAYER OF
    - RECEIVES:
    - CONVERTS:
  3. PHOTOCATHODE
    - MADE OF:
    - EMITS ______ WHEN _______(THIS IS CALLED_________)
A
  1. LIGHT

2/ CESIUM IODIDE
- PHOTONS EXITING PATIENT
- CONERT XRAY TO LIGHT

  1. PHOTOEMISSIVE MATERIAL (CESIUM)
    - EMIT ELECTRONS WHEN STRUCK BY LIGHT FROM INPUT SCREEN
    - PHOTOEMISSION
76
Q
  1. FUNCTION ELECTROSTATIC LENSES:
  2. OUTPUT PHOSPHOR/SCREEN
    - MADE OF:
    - EMIT _______ WHEN _______
  3. WHICH IS SMALLER INPUT OR OUTPUT SCREEN?
A
  1. CHARGED ELECTRODES FOCUS ELECTRONS
  2. OUTPUT:
    - ZINC CADMIUM FULDIDE PHOSPHOR
    - EMIT LIGHT WHEN STRUCK BY ELECTRONS FROM PHOTOCATHODE
  3. OUTPUT PHOSPHOR MUCH SMALLER THAN INPUT
77
Q

During fluoroscopic image intensification, the primary x-ray beam exits the patient and
strikes the ____1____ of the image intensifier.

The input phosphor converts _____2____ to _____3____.

The output phosphor converts ______4___ to ____5_____.

The photocathode absorbs ____6_____ and emits ___7______.

Electrostatic lenses are used to accelerate and focus _____8____.

A
  1. INPUT PHOSPHOR
  2. X-RAY
  3. LIGHT
  4. LIGHT
  5. ELECTRONS
  6. ELECTRONS
  7. LIGHT
  8. ELECTRONS
78
Q
  1. WHAT IS BRIGHTNESS GAIN OF IMAGE INTENSIFIER?
  2. BRIGHTNESS GAIN FORMULA:
  3. WHAT IS MINIFICATION GAIN?
  4. MINIFICATION GAIN FORMULA:
A
  1. MEASUREMENT OF INCREASE IN IMAGE INTENSITY / BRIGHTNESS ACHIEVED BY II
    - ABILITY II INCREASE ILLUMINATION LEVEL OF IMAGE
    - PRODUCT OF MINIFICATION GAIN & FLUX
  2. BG = MINIFICATION X FLUX
  3. RATIO BETWEEN AREA INPUT AND OUTPUT SCREEN
    - INCREASE IN BRIGHTNESS FROM NARROWING THE FLOW OF ELECTRONS
  4. MINGAIN = INPUT DIAMETER^2 / OUTPUT DIAMETER^2
79
Q
  1. WHAT IS FLUX GAIN?
  2. FORMULA FOR FLUX GAIN:
  3. MAGNIFICATION IS FUNCTION OF ________ (WHAT DETERMINES IT.)
  4. EXPLAIN MAGNIFICATION MODE SEQUENCE OF EVENTS:
A
  1. RATIO OF XRAY INCIDENT ON INPUT TO LIGHT PHOTONS EXITING OUTPUT
    - INCREASE IN LIGHT DUE TO CONVERSION EFFICIENCY OF OUTPUT PHOSPHOR
  2. FLUX GAIN = # OUTPUT LIGHT
    PHOTONS / # INPUT XRAY PHOTONS
  3. MAG. FUNCTION OF INPUT PHOSPHOR SIZE
  4. SWITCH MAG MODE ON -> INPUT PHOSPHOR DECREASES -> ELECTROSTATIC LENSE VOLT INCREASED -> ELECTRONS FOCUS AT POINT CLOSER TO INPUT PHOSPHOR = MAGNIFICATION
80
Q
  1. THE SMALLER THE _________ THE MORE THE MAGNIFICATION
  2. HOW MUCH DOES PATIENT DOSE INCREASE WITH MAG?
  3. WHAT HAPPENS TO IMAGE QUALITY WHEN FLURO MAG MODE IS ON?
A
  1. SMALLER INPUT SIZE. = MORE MAG.
  2. 2-4 TIMES
  3. INCREASED SPATIAL RESOLUTION, INCREASED CONTRAST RESOLUTION
81
Q
  1. WHAT HAPPENS TO FOCAL POINT OF IMAGE INTENSIFIER IN MAGNIFICATION MODE?
  2. HOW IS MAGNIFICATION FACTOR DETERMINED?
  3. FORMULA:
A
  1. MOVES AWAY FROM OUTPUT PHOSPHOR
  2. MAG. FACTOR EQUAL TO RATIO OF DIAMETERS OF INPUT
  3. MAGNIFICATION = INPUT DIAMETER / DIAMETER INPUT USED IN MAG.
82
Q
  1. WHICH TUBE REPRESENTS MAGNIFICATION MODE?
  2. MAGNIFICATION ENLARGES _______ BUT DECREASES ________
A
  1. TUBE B
  2. ENLARGE ANATOMY, DECREASES AREA VIEWED
83
Q
  1. WHAT IS VIGNETTING?
  2. WHAT IS TUBE CURRENT IN FLURO?
    - XRAYS TUBE CURRENT?
  3. WHAT IS PULSED-PROGRESSIVE FLURO?
A
  1. EDGE DISTORTION PROBLEM ON PERIPHERY OF IMAGE IN INTENSIFICATION TUBES
    - PINCUSHION DISTORTION
  2. HUNDREDS OF mA
    - 50 TO 1200 mA
  3. AVOID OVERLOAD TUBE HAS TO OPERATE IN PULSATING MODE
    (GENERATOR TURNS ON/OFF)
84
Q
  1. WHAT IS INTERROGATION TIME IN PULSE FLURO?
  2. WHAT IS EXTINCTION TIME?
  3. WHAT IS SUBTRACTION?
A
  1. LENGTH TIME REQUIRED FOR GENERATOR TO COME ON AND REACH NEEDED KVP/MAS
  2. LENGTH TIME REQUIRED FOR GENERATOR TO SHUT DOWN IN PREP FOR NEXT PULSE
  3. BONE & SOFT TISSUE REMOVED FROM IMAGE
85
Q
  1. IN PULSE MODE, ____ PULSES = DECR. PATIENT DOSE
  2. MAXIMUM EXPOSURE RATE FLURO:
    -TYPICAL EXPOSURE RATE:
  3. C-ARM LOWEST EXPOSURE TO OPERATOR WHEN:
A
  1. LESS PULSES PER SECOND= LESS PT DOSE
  2. 10 R/min @ 1 meter
    - 1-3 R / min
  3. XRAY TUBE UNDER TABLE, II ON TOP & STANDING ON II SIDE
86
Q
  1. RELATION BETWEEN SNR & SCATTER?
  2. WHAT AFFECTS NOISE / SNR?
  3. SNR HIGHEST WITH ______ GRID
  4. DOES SOD AFFECT SPATIAL RESOLUTION?
    - WHAT IS DESIRED?
A
  1. INC SCATTER = DECR. SNR
  2. ANYTHING PREVENT PHOTONS FROM REACHING IR WILL CAUSE NOISE & LOW SNR
  3. NO GRID / LOW GRID
  4. YES
    - LONG SOD DESIRED
86
Q
  1. DOES AUTOMATIC BRIGHTNESS CONTROL DECREASE PATIENT DOSE?
  2. DECREASE PATIENT DOSE BY:
A
  1. YES
  2. LAST IMAGE HOLD,
    IMAGE INTENSIFIER CLOSE TO PATIENT
    - PULSE/INTERMITTENED FLURO
    - LESS PULSES PER SECOND
87
Q
  1. RELATION BETWEEN SNR & SCATTER?
  2. WHAT AFFECTS NOISE / SNR?
  3. SNR HIGHEST WITH ______ GRID
  4. DOES SOD AFFECT SPATIAL RESOLUTION?
    - WHAT IS DESIRED?
A
  1. INC SCATTER = DECR. SNR
  2. ANYTHING PREVENT PHOTONS FROM REACHING IR WILL CAUSE NOISE & LOW SNR
  3. NO GRID / LOW GRID
  4. YES
    - LONG SOD DESIRED
88
Q
  1. RELATION BETWEEN SNR & SCATTER?
  2. WHAT AFFECTS NOISE / SNR?
  3. SNR HIGHEST WITH ______ GRID
  4. DOES SOD AFFECT SPATIAL RESOLUTION?
    - WHAT IS DESIRED?
A
  1. INC SCATTER = DECR. SNR
  2. ANYTHING PREVENT PHOTONS FROM REACHING IR WILL CAUSE NOISE & LOW SNR
  3. NO GRID / LOW GRID
  4. YES
    - LONG SOD DESIRED
89
Q
  1. RELATION BETWEEN SNR & SCATTER?
  2. WHAT AFFECTS NOISE / SNR?
  3. SNR HIGHEST WITH ______ GRID
  4. DOES SOD AFFECT SPATIAL RESOLUTION?
    - WHAT IS DESIRED?
A
  1. INC SCATTER = DECR. SNR
  2. ANYTHING PREVENT PHOTONS FROM REACHING IR WILL CAUSE NOISE & LOW SNR
  3. NO GRID / LOW GRID
  4. YES
    - LONG SOD DESIRED

Ketering (13 decks)

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