Part D: Quality control Flashcards
1
Q
- If the slice thickness is reduced by a factor of 2, the factor by which the NSA must be increased to maintain the same SNR (all other factors remaining constant) is:
a. 8
b. 1.41
c. 4
d. 2
A
c. 4
2
Q
- If the slice thickness is increased by a factor of 2 (from 5 to 10mm thickness), the SNR (all other factors remaining constant):
a. Increases by the square root of two
b. increases by a factor of 2
c. Reduces by a factor of 2
d. Reduces by a factor of the square root of 2
A
b. increases by a factor of 2
3
Q
- If the slice thickness increases, SNR (all other factors remaining constant):
a. Increases
b. Decreases
c. Stays the same
d. Is not affected
A
a. Increases
4
Q
- If the slice thickness increases, the spatial resolution (all other factors remaining constant):
a. Increases
b. Decreases
c. Stays the same
d. Is not affected
A
b. Decreases
5
Q
- Changing the size of the voxel in the frequency direction will:
a. Double the scan time
b. Decrease the scan time
c. Have no effect on the scan time
d. Increase the scan time by a factor of 0.5
A
c. Have no effect on the scan time
6
Q
- Factors that affect contrast (contrast to noise or contrast resolution) include all of the following EXCEPT:
a. TR
b. TE
c. TI
d. Flip angle
e. Matrix
A
e. Matrix
7
Q
- SNR is a factor that is measured.
a. True
b. False
A
a. True
8
Q
- CNR is a factor that is measured.
a. True
b. False
A
b. False
9
Q
- Factors that affect spatial resolution (resolution in ‘space’ or detail) include all of the following EXCEPT:
a. FOV
b. Slice thickness
c. Flip angle
d. Matrix
A
c. Flip angle
10
Q
- Factors that affect SNR (signal to noise) include all of the following EXCEPT:
a. TR
b. Field strength
c. FOV
d. Matrix
e. Hour of the day
A
e. Hour of the day
11
Q
- Center frequency is a factor that determines the:
a. Frequency of RF used for excitation
b. Frequency of RF used for signal detection
c. a and b
d. Amplitude and/ or duration of the RF pulse (to determine flip angle)
A
c. a and b
12
Q
- Transmit gain is a factor that determines the:
a. Frequency of RF used for excitation
b. Frequency of RF used for signal detection
c. a and b
d. Amplitude and/ or duration of the RF pulse (to determine flip angle)
A
d. Amplitude and/ or duration of the RF pulse (to determine flip angle)
13
Q
- Geometric accuracy is determined by the:
a. RF system
b. Shim system
c. Gradient system
d. Main magnet system
A
c. Gradient system
14
Q
- During MR imaging, all equipment should be inspected prior to use to be sure that components are in proper working order. Components include:
a. RF coils and cables
b. RF coils and door seals
c. Cables and door seals
d. Quench system
e. All of the above
A
e. All of the above
15
Q
- Reducing the slice thickness by a factor of 2 will reduce the SNR (all other factors remaining constant) by a factor of:
a. 2
b. 1.41
c. 2.5
d. 1.5
A
a. 2
16
Q
- The methods for shimming the main magnetic field are:
a. Retroactive shimming
b. Active shimming
c. Passive shimming
d. b and c
e. a, b, and c
A
d. b and c
17
Q
- The purpose of shimming a magnet is to:
a. Make the B1 field as homogenous as possible
b. Make the B0 field as homogenous as possible
c. Make the scan times as short as possible
d. Correct for improperly tuned gradient coils
A
b. Make the B0 field as homogenous as possible