Hardware Control quiz

High field scanners typically have field strengths greater than or equal to:

1.5 tesla

During a quench of the MR system, patients and employees should be evacuated from the scan room to avoid:

• asphyxiation

• Frostbite

• Ruptured eardrums

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 FDA for infants up to one month of age 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

To prevent outside radiofrequency signals from causing artifacts on the MR images, the scan room is lined with what material?

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:

1. Radiofrequency coils

2. Gradient coils

3. Shim coils

4. Main magnet

The liquid cryogens most often used to maintain field strength in a super conducting MR system are:

Helium

Consistent room temperature of 65-75 degrees Fahrenheit, humidity of 50-70% and sufficient airflow in the MR scan room is recommended to:

Make patients less vulnerable to the RF hearing effects

The coil construction in an MR system, from the innermost aspect to the outer:

1. Radiofrequency coils

2. Gradient coils

3. Shim coils

4. Main magnet

If a facility upgrades its scanner from a 1.5T to a 3T system, what is the expected impact on the available SNR?

Yield an increase of double the SNR

What type of magnet is used with most systems currently manufactured?

Superconducting

What type of MR scanner?

Open magnet

Example of which MR system?

Superconducting magnet

The direction of the magnetic field 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

In a cross sectional view of the MR magnet design, which coils are closest to the patient?

Radiofrequency coils

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

Referring to the SAR impact on the patient, all of the following parameter changes negatively impact pulse duty cycle

1. Increasing the number of slices

2. Using fat suppression

3. Decreasing TR

4. Increasing echo train length

Doubling field strength will result in what impact on SAR potential, if any?

Quadruple SAR

In acquiring ACR OA data, image 210 is used to evaluate for what quality measure?

High contrast spatial resolution

In acquiring ACR QA data, image 211 is used to evaluate for what quality measure?

Geometric accuracy- X/Y gradients

In acquiring ACR QA data, image 212 is used to evaluate for what quality measure?

Geometric accuracy - Z gradient

In acquiring ACR QA data, image 213 is used in evaluating what quality measure?

Low contrast spatial resolution

When acquiring ACR QA data, the slice correlating to image 213 requires what visual discernment?

10 visible spokes of 3 discs each

Transmit gain is a quality measure evaluating for:

Accuracy of flip angles

What is the daily/ weekly QA/QC indicator testing for the accuracy of the magnetic field in determining coil tuning and consistent magnetic field strength?

Center frequency

The liquid cryogens are cooled in a superconducting magnet at a temperature of ______?

4 kelvin

The duty cycle can be viewed as the:

Active gradient time

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