FREE MRSO Static Magnetic Field Safety Questions and Answers

Question 1

An MR technologist is moving a patient into the bore of a 7T MRI scanner.
The patient suddenly reports a strong sensation of vertigo and dizziness.
What is the most likely physiological mechanism responsible for this effect?

Accepted Answer

Lorentz forces acting on ionic currents within the endolymph of the vestibular system.

Answer

Interaction of the static magnetic field with the time-varying gradient fields causing peripheral nerve stimulation.

Answer

Acoustic energy from the gradient coils stimulating the auditory system.

Answer

Radiofrequency energy causing a slight temperature increase in the inner ear.

Question 2

Which of the following forces, exerted by the static magnetic field (B0), poses the most significant risk for projectile accidents in the MR environment?

Accepted Answer

Translational force

Answer

Rotational force (torque)

Answer

Gravitational force

Answer

Lenz force

Question 3

According to the American College of Radiology (ACR) Manual on MR Safety, what is the recommended controlled access area demarcation for the general public concerning the static magnetic field's fringe field?

Accepted Answer

The 5 Gauss (0.5 mT) line

Answer

The 10 Gauss line

Answer

The 1 Tesla line

Answer

The isocenter of the magnet bore

Question 4

A patient with an MR Conditional implant is scheduled for an MRI. The implant's labeling specifies it is safe for use in 1.5T scanners only. The MRSO is asked if the scan can be performed on the facility's 3T scanner, with the reasoning that a higher field strength is not necessarily more dangerous. What is the most appropriate response?

Accepted Answer

No, the conditions for safe use are specific to the static magnetic field strength tested, and safety cannot be assumed at different field strengths.

Answer

Yes, as long as the scan time is reduced by 50% to minimize exposure.

Answer

Yes, but only if a ferromagnetic detection system clears the patient before entry into the scan room.

Answer

No, because the rotational forces (torque) would double, making the implant unsafe.

Question 5

Which of the following describes the translational force exerted by the static magnetic field on a ferromagnetic object?

Accepted Answer

The force is proportional to the product of the magnetic field strength and the spatial gradient of the field.

Answer

The force is uniform throughout the entire magnet room.

Answer

The force is strongest at the magnet's isocenter.

Answer

The force is zero outside of the 5 Gauss line.

Question 6

An MRI staff member who frequently moves around the scanner during patient setup reports experiencing transient symptoms like a metallic taste and occasional headaches. These are recognized as potential biological effects of exposure to what?

Accepted Answer

Movement through the static magnetic field.

Answer

The cryogen boil-off from the magnet.

Answer

The radiofrequency (RF) field during active scanning.

Answer

Acoustic noise from the gradient coils.

An MR technologist is moving a patient into the bore of a 7T MRI scanner.The patient suddenly reports a strong sensation of vertigo and dizziness.What is the most likely physiological mechanism responsible for this effect?

An MR technologist is moving a patient into the bore of a 7T MRI scanner.
The patient suddenly reports a strong sensation of vertigo and dizziness.
What is the most likely physiological mechanism responsible for this effect?