Physics Flashcards
1
Q
- X-RAY TUBE COMPONENTS CONSIST OF:
- WHERE ARE USEFUL PHOTONS EMITTED THROUGH?
- WHAT IS PURPOSE OF TUBE HOUSING
A
- PROTECTIVE HOUSING, CATHODE, ANODE & GLASS ENVELOPE
- WINDOW
- ANYWHERE ELSE IS LEAKAGE - REDUCE LEAKAGE RADIATION
2
Q
- ANY PHOTON PRODUCED ANYWHERE OTHER THAN TARGET IS CALLED:
- WHAT IS MAX LEAKAGE FOR TUBE HOUSING
- WHICH SIDE OF TUBE IS NEGATIVE
- POSITIVE?
A
- OFF FOCUS / STEM
- 100 mR/hr @ 1 meter from tube
- NEGATIVE = CATHODE
- ANODE = POSITIVE
3
Q
- WHEN DO YOU USE SMALL FILAMENT?
- LARGE?
- WHAT IS FILAMENT MADE OF?
- WHY? - EXPLAIN THERMIONIC EMISSION
A
- MORE DETAIL
- BIGGER BODY PARTS B/CB HIGHER KVP & MORE HEAT DISSIPATION - TUNGSTEN & THORIUM
- HIGH MELTING POINT - BOILING OF ELECTRONS IN FILAMENT CREATE CLOUD / SPACE CHARGE
4
Q
- WHAT IS SPACE CHARGE?
- WHAT SENDS ELECTRONS ACROSS TUBE?
- KNOWN AS? - TYPES ANODE:
- WHICH USED?
A
- EXCESS / ABUNDANCE OF ELECTRONS SURROUNDING FILAMENT
- CLOUD OF ELECTRONS
- VOLTAGE
- CURRENT - STATIONARY & ROTATING
– ROTATING B/C - BETER HEAT MANAGING
5
Q
- WHAT MATERIAL IS THE SURFACE OF ANODE
- WHAT MATERIAL IS THE BASE OF ANODE
- WHAT MATERIAL IS THE FILAMENT
- WHAT MATERIAL IS THE ROTOR MADE OF?
WHY ARE THESE USED
A
- TUNGSTEN & RHENIUM
- BASE = MOLYBDENUM
- TUNGSTEN & THORIUM
- COPPER
ALL B/C HEAT DISSIPATION / MANAGEMENT
6
Q
- WHAT IS SPEED OF ROTATING ANODE?
- WHAT IS SPEED OF ROTOR?
- WHAT IS SOURCE OF RADIATION IN X-RAY TUBE?
A
- 3,400 RPM
- SAME SPEED ANODE = 3,400 RPM
- FOCAL SPOT / FOCAL TRACK
7
Q
- HOW BIG IS SMALL FOCAL SPOT?
- SIZE OF
- TECHNIQUE USED - HOW BIG IS LARGE FOCAL SPOT?
- SIZE OF
- TECHNIQUE USED
A
- .1 - 1 mm
- SMALL FILAMENT = SMALL FOCAL SPOT = LOWER TECHNIQUE - .3 - 2 mm
- LARGE FILAMENT = LARGE FOCAL SPOT = HIGHER TECHNIQUE
8
Q
- FILAMENTS ARE LOCATED WHERE?
- FOCUSING CUP FUNCTION:
- HOW DOES IT WORK? - WHAT IS FOCUSING CUP MADE OF?
- CHARGE OF FOCUSING CUP?
A
- IN FOCUSING CUP ON CATHODE
- DIRECT ELECTRON STREAMS TO ANODE
- NEGATIVE CHARGE, ELECTRONS ARE NEGATIVE - MOLYBEDENUM OR NICKEL
- NEGATIVE CHARGE
9
Q
- WHAT IS THE LINE FOCUS PRINCIPLE STATE?
- WHY IMPORTANT? - DIAGNOSTIC X-RAY TUBE TARGET ANGLE IS:
- BASED ON ANODE HEEL EFFECT, WHERE IS INTENSITY STRONGER?
-WHERE IS ABSORPTION GREATER?
A
- REFER TO EFFECTIVE & ACTUAL FOCAL SPOT
- HOW TO PRODUCE GOOD X-RAY / HIGH DETAIL WITHOUT DAMAGING TUBE - 12*
(7-17 IS RANGE) - CATHODE END
FAT CAT- ANODE END (LESS INTENSE)
10
Q
- GOAL OF LINE FOCUS PRINCIPLE:
- RESULTS IN: - WHERE IS EFFECTIVE FOCAL SPOT LOCATED?
-ACTUAL FOCAL SPOT? - HOW IS LINE-FOCUS SPOT PRINCIPLE ACHIEVED?
A
- SMALL EFFECTIVE SPOT
- LARGEST AREA ON TARGET (ACTUAL FOCAL SPOT)
- BETTER DETAIL & HEAT DISSIPATION - EFFECTIVE = ON PATIENT
- ACTUAL = ANODE - ADJUSTING ANODE ANGLE & FILAMENT SIZES
11
Q
- HOW IS ACTUAL FOCAL SPOT ADJUSTED?
- RELATION (DIRECT/INDIRECT)
- WHERE IS IT LOCATED? - HOW IS EFFECTIVE FOCAL SPOT ADJUSTED?
- RELATION (DIRECT/INDIRECT)
- WHERE IS IT LOCATED? - WHAT IS DESIRED?
A
- DETERMINED BY SIZE OF FILAMENT
*WIDER = LARGER FOCAL SPOT
- ON ANODE ANGLE IN X-RAY TUBE - CHANGING ANGLE OF ANODE
- LARGER ANGLE = LARGER FOCAL SPOT
- DIRECTED AT PATIENT - SMALLER ANODE ANGLE = SMALLER EFFECTIVE SPOT = INCREASED DETAIL
12
Q
- WHAT IS AN EXAMPLE OF WHEN ANODE HEEL EFFECT IS USED?
-WHY? - IN REGARDS TO X-RAY EMISSION, WHAT FACTOR EFFECTS CURRENT?
- IN REGARDS TO X-RAY EMISSION, WHAT FACTOR EFFECTS VOLTAGE?
- WHY DOES ANODE HEEL EFFECT OCCUR?
A
- AP T-SPINE, FEMUR
- BECAUSE ANATOMY IS THICKER AT ONE PART THAN OTHER - USING TUBE TO OUR ADVANTAGE FOR UNIFORM DETAIL - mAs
- kVp
- BECAUSE OF TARGET -
A. PHOTONS DIVERGE FROM SOURCE,
B. SOME ARE ABSORBED BY TARGET ON ANODE SIDE, BUT AT CATHODE THEY ARE EMITTED STRAIGHT DOWN / NOT ABSORBED
13
Q
- FILL IN THE CHART
- WHAT ARE THESE FACTORS EFFECT?
A
- SEE IMAGE
- 4 THINGS IMPACT EMISSION SPECTRUM (QUANTITY & QUALITY COMING FROM TUBE)
14
Q
- WHAT ARE THE PRIMARY FACTORS?
- WHAT IS QUALITY? AKA?
- WHAT IS QUANTITY? AKA?
A
- mAs, kVp & DISTANCE
- KVP - VOLTAGE
- MAS - CURRENT
15
Q
- WHY DOES FILTRATION DECREASE QUANTITY?
- HOW DOES KVP AFFECT QUANTITY?
- DO FILTRATION DECREASE AMOUNT OF PHOTONS CREATED?
A
- FILTERING OUT LOW ENERGY PHOTONS / DECREASES
- KVP ACCELERATES ELECTRONS FROM CATHODE TO ANODE
- HIGHER KVP = MORE ELECTRONS ACROSS TUBE = MORE HIT ANODE = MORE PHOTONS EMITTED - # PHOTONS COMING OUT OF TUBE NOT NUMBER PHOTONS PRODUCED
16
Q
- WHAT IS mA?
- WHAT IS mAs?
- RELATION BETWEEN ABOVE TWO - mAs PRIME CONTROLLER OF:
A
- TUBE CURRENT / NUMBER OF ELECTRONS TRAVELING TUBE
- CONTROLS # XRAYS PRODUCED (QUANTITY)
- INC. MAS = INC. TUBE CURRENT = INC. QUANTITY
- DENSITY (FILM) OR IR EXPOSURE (DIGITAL)
17
Q
- WHAT CONTROLS IR EXPOSURE IN DIGITAL?
- DIRECT OR INDIRECT RELATION?- INSUFFICIENT =
- EXCESSIVE =
- WHAT CONTROLS CONTRAST
A
- mAs
- DIRECT
- INSUFFICIENT = UNDEREXPOSED
- EXCESSIVE = OVEREXPOSED (TOO DARK)
18
Q
- WHAT DOES KVP AFFECT?
- EXPLAIN HOW ABOVE OCCURS:
(INCREASING KVP = ______________)
A
- QUANTITY & QUALITY
- INCREASE ENERGY OF ELECTRONS IN TUBE CURRENT
= INCREASE # PHOTONS PRODUCED
= INC. ENERGY OF XRAYS
= INCREASED PENTRABILITY
= INCREASED DENSITY / IR EXPOSURE
19
Q
1.HOW DOES KVP CONTROL CONTRAST?
- HIGH KVP = _______ CONTRAST
- LOW KVP = _________ CONTRAST
- FILL IN THE IMAGE
ARE THESE PRIME FACTORS?
A
- SCATTER
- INCREASE KVP = INCREASE SCATTER = FOGGY IMAGE (INCREASED DARKENING ON IMAGE) - HIGH KVP = LOW CONTRAST
- LOW KVP = HIGH CONTRAST
- HIGH KVP = LOW CONTRAST
- SEE IMAGE
- FILTRATION IS NOT** ONLY MAS, KVP & DISTANCE
20
Q
- DOES DISTANCE IMPACT QUALITY OF IMAGE?
- QUANTITY?
- WHY DOES OR DOESNT ABOVE AFFECT IT? (EXPLAIN EACH)
A
- NO - DOESNT CHANGE PENETRABILITY OR INCREASE/DECREASE AMOUNT X-RAYS
- YES! INVERSE SQUARE LAW, GREATER DISTANCE = LOWER EXPOSURE/QUANTITY - FURTHER TUBE FROM PATIENT
= MORE BEAM DIVERGENCE
= LESS PHOTONS HITTING PATIENT
= LESS HITTING IR
= DECREASED QUANTITY
21
Q
- LABEL THE IMAGE
- WHICH IS OUTSIDE ENVELOPE, THE STATOR OR ROTOR?
- 3 PARTS OF ANODE:
A
- SEE IMAGE
- STATOR OUTSIDE
- TARGET (ACTUAL FOCAL SPOT), STATOR & ROTOR
22
Q
- WHAT IS HERTZ?
-WHAT DOES IT MEASURE? - WHAT IS IMAGED?
- WHAT IS ONE CYCLE?
A
- 1 Hz = 1 CYCLE/SECOND
- FREQUENCY - SINE CURVE - ONE CYCLE
- STARTS 0 - GOES HIGH POINT - BACK TO 0 - GOES TO NEGATIVE THAN BACK 0
23
Q
- WHAT TERM IS LOW POINT OF CURVE?
- HIGHPOINT? - WHAT DOES HIGH AMPLITUDE MEAN?
- U.S. HERTZ =
- IN U.S, HOW MANY TIMES DOES CURRENT ALTERNATE & CHANGE DIRECTIONS?
A
- LOW POINT = TROUGH
HIGHPOINT = CREST - CREST (PEAK POINT) IS HIGH
- 60 HZ (60 CYCLES/SECOND)
- 120 TIMES (2X CYCLE/SECOND) ^
24
Q
- DIFFERENCE BETWEEN DIRECT & ALTERNATING CURRENT?
- WHICH DOES X-RAY CIRCUIT REQUIRE?
- WHAT CONVERTS AC TO DC?
A
- DIRECT = ONE DIRECTION,
- ONLY POSITIVE #S
- ALTERNATING = CHANGES DIRECTION,- POSITIVE & NEGATIVE #S
- ONLY POSITIVE #S
- DIRECT (XRAY TUBE) AND ALTERNATING (TRANSFORMER, GENERATOR, TIMING UNIT)
- RECTIFIER
25
Q
- X-RAY TUBE USES _______ CURRENT
- WHAT IS IMAGED?
- WHAT IS PURPOSE OF RECTIFIER?
A
- DIRECT CURRENT
- DIRECT CURRENT
- CONVERRT AC TO DC
26
Q
- WHAT IS SOLID-STATE DIODE REFER TO?
- WHAT IS RECTIFIER MATERIAL?
- WHAT CURRENT IS USED IN TRANSFORMER OR GENERATOR?
A
- RECTIFIER IN X-RAY
- SILICON
- ALTERNATING
27
Q
- N-TYPE SILICON:
A. CONTAINS _________
B. TYPE OF ATOM: ______
C. CHARGE: - WHAT IS N-TYPE REFERRING TO?
- HOW ARE RECTIFIERS TESTED?
A
- A. ARSENIC
B. DONOR ATOM (B/C HAS AN EXTRA ELECTRON)
C. NEGATIVE - SEMICONDUCTOR IN RECTIFIER
- SPIN-TOP TEST