hardware/instrumentation Flashcards

1
Q

a 6 in surface coil (linear coil) is able to receive signal how deep in pt?

A
3 in 
(SNR penetration depth=1/2 of coil diameter
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2
Q

permanent magnets with a vertical magnetic field use surface coils that are ___ because the secondary magnetic field (B1) created by RF coils must be perpendicular to orientation of B0

A

solenoids

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3
Q

what is another word for a circularly polarized transmission or receiver coil with two orthogonal transmission or receiver channels?

A

quadrature

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4
Q

The CPU (central processing unit) used to plot and adjust slices in in an MR sequence in the ___

A

scan control room

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5
Q

The array processor is responsible for reconstructing the collected MR images/data using the FT, and is located in the ___

A

MR equipment room

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6
Q

The RF power amplifier is located within the ___

A

equipment room

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7
Q

doubling the field strength will ___ SNR

A

double

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8
Q

the intensity limit for static magnetic fields in clinical use is limited by the FDA to___ field strength for all patients, but ___ for all patients over one month of age

A

4T and 8T

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9
Q

doubling field strength results in a ___ increase in SAR potential

A

fourfold

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10
Q

liquid cryogens are cooled in a superconducting magnet at a temp of ___ ___ ___

A

4 Kelvin
270 degrees C
-452 degrees F

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11
Q

What information is obtained from QA?

A
  • center frequency
  • transmit gain
  • SNR
  • geometric accuracy
  • low/high contrast spatial resolution
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12
Q

what does QA stand for and what goal does it stand for?

A
  • quality assurance

- maintaining a desired level of consistency and image quality requirements in radiology

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13
Q

what does QC stand for and what does it reflect?

A
  • Quality control

- the set of activities used to fulfill the requirements for quality.

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14
Q

what does SPT stand for?

A

system performance testing

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15
Q

What does PIQT stand for?

A

periodic image quality test

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16
Q

which temperature is desired in the scan room to reduce potential of patient burns due to SAR absorption?

A

65-75 degree F

17
Q

what is the humidity that is desired in the scan room to reduce potential of patient burns due to SAR absorption?

A

50-70%

18
Q

what is sagittal localizer of ACR Phantom used for?

A

ensuring geometric accuracy of Z gradient

19
Q

What is the axial view of ACR Phantom (slice with squares) used for?

A

ensuring geometric accuracy of X and Y gradients

20
Q

What is axial view of phantom with small dotted squares used for?

A

high contrast resolution

21
Q

what is the axial view of phantom with ten lines of spokes used for?

A

low contrast resolution

22
Q

10 mT/m =

A

1 G/cm

23
Q

1T/m =

A

100 G/cm

24
Q

Coils closest to patient to farthest away…

A

RF coils, gradient coils, shim coils, and main magnet

25
Q

which factors negatively affect that pulse duty cycle?

A
  • increase # of slices
  • emplyment of fat sat pulses (SPAIR requires higher TR compared to SPIR)
  • Utilization of pre-saturation slabs/bands
  • increased ETL