Safety Term Quiz Part 1/2

all areas freely accessible to the public

MRI zone 1

patients and guests are under the supervision of MR personnel

MRI Zone 2

typically considered the control room or technologist console area

MRI Zone 3

typically contains the 5 gauss line

MRI Zone 4

contains the MRI scanner

MRI Zone 4

An item that poses no known hazards in all MR imaging environments.

MR Safe

An item that poses no known risk in specific static fields with specific spatial gradients or RF fields.

MR Conditional

An item that is known to pose hazards in all MR environments.

MR UNsafe

An item that has a deflection greater than 45 degrees in the presence of a magnetic field.

MR UNsafe

What are some things that fall under the Static Magnetic field?

Magnetophosphenes, Magnetohydrodynamic, and Magnetohemodynamic, Translation Effects (Projectiles), and Rotational Forces (Torque)

what are some things that fall under Radiofrequency Magnetic Fields?

Thermal issues (SAR), Focal burns (burns), and Resonant circuitry

What are some things that fall under the Gradient Magnetic Fields?

Peripheral nerve stimulation and Auditory safety consideration

Non-MR Personnal

An individual that has not received safety training within the last 12 months and requires supervision in the MR environment. Ex. Patient or firefighter

Level 1 MR Personnel

An individual that has received MR safety training within the last 12 months. Ex. Tech aid or assistant- only responsible for themselves

Level 2 MR Personnel

An individual who has received extensive MR safety training within the last 12 months. Ex. MR technolgist or MRSO

What is Magnetophosphenes and what are the effects?

Flashes of light caused by direct stimulation of the optic nerve- IN/OUT of the MRI scanner

What is magnetohydrodynamic and what are the effects?

Bodily fluids (e.g. blood vessels) perpendicular to the static

magnetic field can act as a conductor

What is magnetohemodynamic and what are the effects?

Increased amplitude of T wave causes confusion with MRI cardiac gating computer software

Lenz Law?

induced voltage will generate a secondary magnetic field that will act against the primary field. Ex: Pacemaker may move inside patient - opposing magnet

Specific absorption rates (SAR)?

The number of Watts of RF energy per kilogram of body weight in an imaging sequence

Screening

In zone 11 and must be screened prior to entering zone 1v

Can pregnant people get an MRI?

Yes, but don’t like to do it in 1st trimester and no gadolinium/contrast

All patients must be monitored ___ and ___

visually and verbally

Res ipa loquitur

Respondeat superior

what is Cryogens?

Keep the magnet cold and used in superconducting system-relate to liquid helium or liquid nitrogen

Quenching

a sudden loss of cryogens/superconductivity

What is dB/dx

change in magnet / change in distance

What is dB/dt

Change in magnet/ change in time

What can stop a headache and fatigue in a 2.0 T static field?

Taking them away from the Static field

what is the ambient zone temperature?

67 degrees Freiheit

1.5 T can have WHAT LENGTH enter the MRI?

25cm-30cm

3 T can have WHAT LENGTH enter the MRI?

12cm- 15cm

What can cryogen do?

can displace oxygen creating an asphyxiation hazard

What is a fringe field?

Magnetic field extending outside the MRI magnet/ the further you go, the weaker it becomes