MRI physics Final Exam 2024/2025(Questions With 100% Correct Answers)A+ Graded Verified
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Course
MRI physics
Institution
MRI Physics
What type of nonionizing electromagnetic radiation does MRI utilize? - ANSWER Radio Frequency
Preventing potential serious injury or death from strong magnetic field strengths requires:
1. a knowledgeable and mindful MR technologist
2. Controlled access to the magnetic field
3. a detaile...
MRI physics Final Exam 2024/2025(Questions With
100% Correct Answers)A+ Graded Verified
What type of nonionizing electromagnetic radiation does MRI utilize? - ANSWER Radio
Frequency
Preventing potential serious injury or death from strong magnetic field strengths
requires:
1. a knowledgeable and mindful MR technologist
2. Controlled access to the magnetic field
3. a detailed medical history of anyone entering the room - ANSWER 1, 2, and 3
When protons spin in place within an atom, they create:
a. a small magnetic field
b. an electrical charge
c. pressure on the electrons
d. a small hydrogen moment - ANSWER a. a small magnetic field
The process of producing voltage using magnetic fields is called:
a. static electricity production
b. non-magnetic generation
c. electromagnetic induction
d. the Larmar equation - ANSWER c. electromagnetic induction
The steepness of the gradient slope or the power of the gradient is termed the:
a. gradient direction
b. gradient amplitude
c. gradient rise time
d. gradient slew rate - ANSWER B. gradient amplitude
1 Tesla is equal to _________ Gauss. - ANSWER 10,000
The static magnetic field of a permanent magnet generally follows which direction?
a. Vertically from the ceiling to the floor
b. horizontally from the inner bore to the wall
c. horizontally along the long axis of the patients body in the bore
d. in a straight line from the inner bore to the wall perpendicular to the bore - ANSWER
a. vertically from the ceiling to the floor
Precessional frequency is determined by the ___________ equation.
a. Precessional
b. Magnetic Frequency
c. Larmor
,d. Faraday - ANSWER c. Larmor
Adding additional electrical coils to maintain magnetic field homogeneity is called:
a. active shimming
b. active shielding
c. passive shimming
d. gross adjustments - ANSWER a. active shimming
The ________ line is a perimeter around the scanner defining where the static field is
potentially hazardous (near the foot end of tabletop)
a. 3.0 T line
b. 3-gauss circle
c. 1.5 T circle
d. 5-gauss line - ANSWER d. 5-gauss line
The rapid loss of voltage induced within the coil after the RF excitation due to relaxation
is called:
a. longitudinal precession
b. transverse magnetization
c. repetition time
d. free induction decay - ANSWER free induction decay
A superconducting magnetic field generally flows:
a. horizontally through the bore of the magnet
b. from the inner bore to the floor
c. in a diagonal line from the bore to the floor
d. vertically from the ceiling to the floor - ANSWER horizontally through the bore of
the magnet
what is used to cool the wires of superconducting magnets?
a. solid hydrogen blocks
b. special electrical fans
c. liquid cryogens
d. synthetic antifreeze - ANSWER liquid cryogens
Why are hydrogen protons predominately used to create MR images?
1. they have an odd number of protons
2. they are abundant in the human body
3. they are negatively charged - ANSWER 1 and 2
More hydrogen protons are aligned parallel to the main magnetic field in the ________
energy state.
a. high
b. medium
,c. average
d. low - ANSWER low
T/F If working with a magnetically shielded MR system, one does not have to be as
careful about bringing ferrous objects around the magnet. - ANSWER False
Which of the following statements is true regarding resistive magnets?
a. resistive magnets have higher field strengths than Superconducting Magnets
b. They are commonly used in trauma hospitals
c. they tend to inexpensive to operate
d. resistive magnets can be shut off easily by discontinuing the power - ANSWER
resistive magnets can be shut off easily by discontinuing the power
In a well-known accident that occurred in July 2001, __________ flew through the
scanner room, striking and killing a 6-year-old boy.
a. an emergency crash cart
b. a set of forceps
c. a wheelchair
d. an oxygen tank - ANSWER d. an oxygen tank
What is the absorption rate averaged over the entire body or over a small sample volume
termed?
a. RF absorption rate
b. specific absorption rate
c. global absorption rate
d. total RF absorption rate - ANSWER b. Specific Absorption Rate
Coils used within the MR imaging process typically are used to:
a. return signal
b. alter signal
c. receive signal
d. validate signal measurements - ANSWER receive signal
The gradient field can potentially stimulate a patient's _________.
a. dreams
b. skin temperature
c. peripheral nerves
d. eyesight - ANSWER peripheral nerves
SAR is an abbreviation for: - ANSWER Specific Absorption Rate
Which of the zones established by the ACR regarding MR safely, houses the actual
magnet? - ANSWER Zone 4
, According to ACR safety guidelines, Level 1 MR personnel have :
a. been thoroughly trained in MR safety
b. extensively trained MR safety and in full control of the Zones
c. participated in minimal MR safety educational programs
d. no training - ANSWER participated in minimal MR safety educational programs
T/F Parents who enter the MR scanning room with their children do NOT need to go
through the entire safety screening process. - ANSWER false
Which magnet field involved in MRI imaging is a TVMF?
a. gradient magnet
b. RF magnet
c. main magnet
d. shim magnet - ANSWER gradient magnet
The strength and direction of a magnetic field may be symbolized as:
a. a sine wave
b. a gyro-magnetic ratio
c. a vector
d. a set of coordinate axes - ANSWER a vector
What is the function of shim coils?
a. they act a RF receivers
b. they produce magnetic field gradients
c. they maintain the magnetic field homogeneity
d. they transmit RF pulses - ANSWER they maintain the magnetic field homogeneity
The sensitive volume size (sensitivity profile) extends to the _________ of the coil and to
the depth into the patient equal to _______ % of the diameter of the coil. - ANSWER
diameter, 75
The angle at which the NMV is moved by the RF pulse in relation to B0 is called the
__________? - ANSWER Flip angle
Long term biological effects associated with the main magnetic field include:
a. there are no known long-term effects
b. magneto-phoshenes
c. peripheral nerve stimulation
d. magnet hemo-dynamic effects - ANSWER there are no known long-term effects
Safety considerations associated with RF fields include:
a. ferrous attraction
b. peripheral nerve stimulation
c. acoustic noise
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