Hardware control Flashcards
High field scanners typically have field strengths greater than or equal to:
1.5 Tesla
Consistent room temperature of 65-75°F, humidity of 50-70%, and sufficient air flow in the MR scan room is recommended to
Make patients less vulnerable to the RF heating effects
In a cross sectional view of the MR magnet design, which coils are closest to the patient?
Radiofrequency coils
The liquid cryogens are cooled in a superconducting magnet at a temperature of
4° Kelvin
Which of the following is NOT a magnetic field associated with MR imaging?
Gravitational earth magnetic fields
The purpose of shimming the magnet is to
make the B0 field as homogenous as possible
The array processor is responsible for:
Reconstructing the images using the Fourier transform
: In order for energy to be efficiently transferred between a transmitter and receiver, the two must be at the same
Frequency
The _____ is located within an equipment room.
RF power amplifier
During a quench of the MR system, patients and employees should be evacuated from the scan room to avoid
A. Damage to tympanic membranes
B. Frostbite
C. Asphyxiation
D. All of the above
all of the above
Field strength at magnet isocenter is measured in units of:
Tesla
The unit of measurement of the magnetic field surrounding the periphery of the MR scanner is expressed as:
Gauss
The intensity limit for a static magnetic field in clinical use is limited by the Food and Drug Administration (FDA) to _____________?
4 Tesla
The patient image display with sequence parameter visualization is located in the
Scan control room
The local RF coil used to image a human brain is typically located/kept in the __________.
Magnet room
The CPU used to plot and adjust slices in an MR sequence is located:
Scan control room
Radiofrequency (RF) shielding can be achieved by lining the scanner room walls with
Copper
The location of the coils installed in the MRI scanner, from the inner point closest to the patient to the outer most edge, are
Radiofrequency coils, gradient coils, shim coils, main magnet
The liquid cryogens most often used to maintain field strength in a super conducting MR system are:
Helium
The coil construction in an MR system, from the innermost aspect to the outer:
Radiofrequency coils, gradient coils, shim coils, main magnet
Doubling the magnetic field strength will:
Yield an increase of double the SNR
: What type of magnet is used with most systems currently manufactured
Superconducting
: Image 78 is an example of what type of MR scanner?
Open magnet
Image 79 is an example of which MR system?
Superconducting magnet
The direction of the magnetic field in Image 79 is:
Horizontal
: Image 82 was acquired at what field strength?
1.5 Tesla
Passive shielding can be accomplished by lining the MR room with ___________.
Steel
Active shielding can be defined as:
Superconducting windings within the MR scanner, reducing the fringe magnetic field
_________ would be used to contain the RF in an MR magnet room.
Copper
___________ could be used to line the walls and/or floors of the MR magnet room to reduce the fringe field, and is defined as __________ shielding
Steel; passive
