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MRI Bill Faulkner > Chapter 5 - questions > Flashcards

Chapter 5 - questions Flashcards

1
Q

The external magnetic field is annotated as:
a. B1
b. B0
c. Z
d. B

A

b. B0

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2
Q

A field strength of 1.5 Tesla is equivalent to:
a. 10,000 G
b. 20,000 G
c. 15,000 mT
d. 15,000 G

A

d. 15,000 Gauss

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3
Q

Which of the following systems utilizes technology to create a magnetic field that cannot be removed (turned off)?
a. resistive
b. permanent
c. superconductive

A

b. permanent

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4
Q

Which of the following systems utilizes technology to create a magnetic field that can easily and routinely be removed (turned off)?
a. resistive
b. permanent
c. superconductive

A

a. resistive

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5
Q

Reducing the temperature of a conductor reduces
a. current
b. resistance
c. voltage
d. conductor life

A

b. resistance

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6
Q

The cryogen most commonly used to maintain the magnet coils at a superconducting temperature is
a. helium
b. hydrogen
c. oxygen
d. xenon

A

a. helium

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7
Q

the sudden loss of superconductivity and thus a loss of the magnetic field in a superconducting magnet is known as a
a. steady state
b. quench
c. ramp down

A

b. quench

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8
Q

which of the following is utilized to obtain very high magnetic fields
a. resistive
b. permanent
c. superconductive

A

c. superconductive

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9
Q

in a cylindrical magnet, the direction of the magnetic field is oriented along which axis of the patient’s body
a. X
b. Y
c. Z

A

c. Z

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10
Q

which of the following materials is commonly used for passive magnetic shielding within the walls of the MRI room
a. copper
b. iron
c. bismuth
d. lead

A

b. iron

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11
Q

For adults, what is current FDA guideline limit for exposure to a magnetic field?
a. 8 T
b. 4 T
c. 3 T
d. 7 T

A

a. 8 Tesla

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12
Q

The biologic effects which is seen as an elevation of the T-wave on ECG tracing when a patient is placed in 1.5 T cylindrical bore magnet is known as:
a. peripheral nerve stimulation
b. teratogenesis
c. magnetohydrodynamic effect
d. magnetophosphene stimulation

A

c. magnetohydrodynamic effect

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13
Q

rotation or torque forces are greatest
a. when one enters the scan room
b. at isocenter
c. at the foot of the table

A

b. at isocenter

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14
Q

which of the following materials is commonly used for RF shielding
a. lead
b. iron
c. bismuth
d. copper

A

d. copper

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15
Q

which of the following coil designs uses 2 elements to produce 2 waveforms 90 degress out of phase with each other
a. linear
b. quadrature
c. multi-channel (phased array)

A

b. quadrature

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16
Q

the FDA guideline limits SAR for the head to
a. 4.0 W/kg
b. 8.0 W/kg
c. 3.2 W/kg
d 2.0 W/kg

A

c. 3.2 W/kg

17
Q

the FDA guideline limits SAR averaged over the whole body
a. 4.0 W/kg
b. 8.0 W/kg
c. 3.2 W/kg
d 2.0 W/kg

A

a. 4.0 W/kg

18
Q

the normal operating mode with limit the whole-body SAR average to no greater than
a. 4.0 W/kg
b. 8.0 W/kg
c. 3.2 W/kg
d 2.0 W/kg

A

d 2.0 W/kg

19
Q

increasing the flip angle from 45 degrees to 90 will increase SAR by a factor of
a. 2
b. 4
c. 6
d. 8

A

b. 4

20
Q

which of the following sequences is of most concern with regard to SAR
a. fast spin echo
b. conventional spin echo
c. echo planar imaging (EPI)

A

a. fast spin echo

21
Q

patients can receive burns if their arms are touching the sides of the magnet bore
true or false

A

true

22
Q

the primary purpose of the gradient magnetic fields produced by the gradient fields is to
a. reduce SAR
b. reduce acoustic noise
c. spatial encode the MR signals

A

c. spatial encode the MR signals

23
Q

the gradient coil which varies the magnetic field along the head to foot direction of the body is annotated
a. x
b. y
c. z

A

c. z

24
Q

Slew rate is defined as
a. maximum amplitude plus rise time
b. maximum amplitude divided by rise time
c. rise time multiplied by max amplitude

A

b. maximum amplitude divided by rise time

25
Q

the FDA recommends hearing protection for sound levels above
a. >99 dB
b. >50 dB
c. >60 db

A

a. >99db

26
Q

the control room for an MRI system is considered to be within zone III
true or false

A

true

27
Q

any type of metallic device, if it can be brought into Zone IV will be labeled as
a. MR safe
b. MR conditional
c. MR unsafe

A

b. MR conditional

28
Q

who is responsible for the final safety determination to scan a patient
a. MR tech
b. Referring Physician
c. MR radiologist

A

c. MR Radiologist

29
Q

the accepted standard to screen for metal fragments in the eye is
a. thin slice CT
b. radiographs
c. split lamp exam

A

b. radiographs

MRI Bill Faulkner (12 decks)

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