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MRI > MIDTERM-PT. 1 > Flashcards

MIDTERM-PT. 1 Flashcards

1
Q

WHAT ARE THE 3 PRINCIPAL TYPES OF MAGNETS:

A
  1. NATURAL
  2. PERMANENT
  3. ELECTROMAGNETS
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2
Q

MAGNET: EARTH

A

NATURAL

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3
Q

MAGNET: ARTIFICIALLY PRODUCED

A

PERMANENT

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4
Q

MAGNET: CONSIST OF WIRES

A

ELECTROMAGNETS

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5
Q

WHAT ARE THE INTERACTION WITH MATTER: (3)

A
  1. DIAMAGNETIC
  2. FERROMAGNETIC
  3. PARAMAGNETIC
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6
Q

MATERIALS THAT ARE UNAFFECTED WHEN BROUGHT INTO A MAGNETIC FIELD

A

DIAMAGENETIC

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7
Q

STRONGLY ATTRACTED BY A MAGNET; ALNICO

A

FERROMAGNETIC

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8
Q

AN ALLOY OF ALUMINUM, NICKEL AND COBALT (MOST USEFUL MAGNETS PRODUCED BY FERRIMAGNETIC MATERIAL)

A

ALNICO

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9
Q

MATERIALS THAT ARE BETWEEN THE CLASSIFICATION OF DIAMAGNETIC AND FERROMAGNETIC

A

PARAMAGENTIC

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10
Q

SLIGHTLY ATTRACTED TO A MAGNET AND LOOSELY INFLUENCED BY AN EXTERNAL MAGNETIC FIELD

A

PARAMAGNETIC

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11
Q

CONTRAST AGENTS USED IN MRI ARE _____

A

PARAMAGNETIC

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12
Q

THE SI UNIT OF MAGNETIC FIELD STRENGTH

A

TESLA

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13
Q

OLDER UNIT FOR MAGNETIC FIELD STRENGTH

A

GAUSS

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14
Q

1 TESLA= ______ GAUSS

A

10,000

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15
Q

THE EARTH’S MAGNETIC FIELD AT THE EQUATOR IS ____ uT

A

50

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16
Q

the EARTH’S MAGNETIC FIELD AT THE POLES IS ____ uT

A

100

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17
Q

LOWER TESLA = ___ QUALITY

A

LOWER

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18
Q

TYPICALLY COILS OF WIRE THROUGH WHICH A MAGNETIC FIELD IS INDUCED

A

RESISTIVE MAGNETS

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19
Q

ADVANTAGES: (MAGNET)
1. THEY ARE LIGHTER IN WEIGHT THAN PERMANENT MAGNETS
2. CAPITAL COSTS ARE LOW
3. DOES NOT REQUIRE CRYOGENS

A

RESISTIVE MAGNETS

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20
Q

A LIQUID HELIUM INSULATOR; MAINTAINS NORMAL TEMPERATURE

A

CRYOGENS

21
Q

DISADVANTAGES: (MAGNET)
1. HIGH COSTS
2. LARGE QUANTITIES OF POWER REQUIRED TO MAINTAIN THE MAGNETIC
THE MAXIMUM FIELD STRENGTH IN A SYSTEM OF THIS TYPE IS LESS THAN 0.3T DUE TO ITS EXCESSIVE POWER REQUIREMENTS
3. SCAN TIMES ARE LONGER
4. RESISTIVE SYSTEM IS SAFE; CAN BE EASILY TURNED OFF INSTANTANEOUSLY
3. CREATE SIGNIFICANT STRAY FRINGE MAGNETIC FIELDS

A

RESISTIVE MAGNETS

22
Q

MAGNET: FIELD STRENGTH IS LESS THAN 0.3T

A

RESISTIVE MAGNETS

23
Q

THE MOST COMMONLY USED MAGNET

A

PERMANENT MAGNENT

24
Q

_____ IS USED TO MAKE PERMANENT MAGNETS

A

ALNICO ALLOY

25
Q

ADVANTAGES: (MAGNET)
1. THEY HAVE AN OPEN DESIGN; (CHILDREN, OBESE, AND CLAUSTROPHOBIC PATIENTS ARE SCANNED WITH EASE)
3. INTERVENTIONAL AND DYNAMIC PROCEDURES ARE POSSIBLE
4. THEY REQUIRE NO POWER SUPPLY
5. LOW IN OPERATING COSTS

A

PERMANENT MAGNETS

26
Q

DISADVANTAGES: (MAGNET)
1. THEY ARE EXCESSIVELY HEAVY
2. ONLY LOW FIXED FIELD STRENGTHS (0.2- 0.3 T) CAN BE ACHIEVED
3. LONGER SCAN TIMES ARE NEEDED, DUE TO LOWER FIELD STRENGTHS
4. COST OF THE MAGNET
5. HEAVY SUPPORTING STRUCTURES

A

PERMANENT MAGNETS

27
Q

MAGNET: FIELD STRENGTH IS 0.2- 0.3 T

A

PERMANENT MAGNET

28
Q

MAGNET: CONSIST OF COIL MADE OF NIOBIUM-TITANIUM (Nb-Ti) ALLOY

A

SUPERCONDUCTING MAGNETS

29
Q

ADVANTAGES: (MAGNET)
1. IT GIVES MAGNETIC FIELD STRENGTH (0.5-3T) WITH LOW POWER REQUIREMENTS
2. LOW OPERATING COSTS
3. RESISTANCE IS VIRTUALLY ELIMINATED, THERE IS NO LONGER A MECHANISM TO DISSIPATE CURRENT
4. NO ADDITIONAL POWER INPUT IS REQUIRED TO MAINTAIN THE HIGH MAGNETIC FIELD STRENGTH
5. ADVANCED APPLICATIONS ARE POSSIBLE AND OPTIMUM IMAGE QUALITY IS OBTAINED

A

SUPERCONDUCTING MAGNETS

30
Q

MAGNET: FIELD STRENGTH IS 0.5- 3T

A

SUPERCONDUCTING MAGNETS

31
Q

____ HAS A SPECIAL COOLING AGENT CALLED ____ ARE USE TO PRODUCE LOW TEMPERATURE (4K)

A

SUPERCONDUCTOR MAGNETS
LIQUID CRYOGENS

32
Q

THE ELECTROMAGNETIC COILS ARE PLACED IN AN INSULATED CHAMBER CALLED ____ (CONTAINS HELIUM)

A

DEWAR/ CRYOSTAT

33
Q

THE PROCESS OF BRINGING THE SUPERCONDUCTING MAGNETS TO THE NECESSARY TEMPERATURE IS CALLED ____

A

RAMPING

34
Q

REFERS TO A MAGNET’S SUDDEN LOSS OF SUPERCONDUCTIVITY WITH SUBSEQUENT BREAKDOWN OF THE MAGNETIC FIELD; SUDDEN LOSS OF ABSOLUTE O TEMPERATURE

A

QUENCHING

35
Q

DEWAR: 2 TYPES OF CHAMBER

A
  1. OUTER CHAMBER
  2. INNER CHAMBER
36
Q

CONTAINS LIQUID NITROGEN

A

OUTER CHAMBER

37
Q

CONTAINS LIQUID HELIUM

A

INNER CHAMBER

38
Q

THIS RESULTS IN HELIUM ESCAPING FROM THE CRYOGEN BATH EXTREMELY RAPIDLY

A

QUENCHING

39
Q

63%; MAGNETIZATION

A

T1

40
Q

ANATOMY & SPIN (INTERACTION)

A

T2

41
Q

ARE BASED ON THE FACT THAT NUCLEI OF CERTAIN ELEMENTS HAVE A MAGNETIC MOMENT

A

MRI

42
Q

THE _____ IN MRI IS DUE TO THE ANGULAR MOMENT

A

PRECESSION

43
Q

ROTATION OF AN OBJECT AROUND THE DIRECTION OF A FORCE ACTING ON THAT OBJECT

A

PRECESSION

44
Q

USES THE SIGNAL FROM THE NUCLEI OF HYDROGEN ATOMS FOR IMAGE GENERATION

A

MRI

45
Q

PERTAINS TO ROTATION (CLOCKWISE/COUNTER CLOCKWISE)

A

ANGULAR MOMENT

46
Q

PERTAINS TO THE ALIGNMENT; PARALLEL/ ANTI-PARALLEL

A

MAGNETIC MOMENT

47
Q

NORMALLY PROTONS ARE ALIGNED IN RANDOM FASHION ALIGNMENT: (2)

A
  1. PARALLEL
  2. ANTI-PARALLEL
48
Q

TYPES OF SPIN: (ANGULAR MOMENT)

A
  1. CLOCKWISE
  2. COUNTERCLOCKWISE

MRI (5 decks)

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