question

SAR

answer

Rate of energy that may be deposited in tissue

question

Zone 1

answer

Areas outside MR environment and accessible to general public

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Zone 2

answer

Are under supervision of MR staff where pts are screened and hx is taken

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Zone 3

answer

Restricted area strictly limited and controlled by MR personnel. Should be clearly marked as potentially hazardous.

question

Zone 4

answer

Room in which the MR scanner is housed and area that poses the most potential risk

question

Level 1 personnel

answer

Anyone who has completed basic MR training and is permitted in zones 1-3

question

Level 2 personnel

answer

Possesses comprehensive MR training and understand the potential for hazardous situations that may arise from a wide variety of risks associated with Zones 3 and 4

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MR personnel

answer

Qualified to perform screening process before permitting non-MR personnel into Zone 3

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90 dB

answer

Acoustic noise can reach up to:

question

MR-compatible

answer

Type of wires or leads that may be used during the scanning process

question

cross points

answer

cables that touch, loop over themselves, or come in contact with the RF coil

question

drug patches

answer

Delivers medication and may have metallic backing and are at risk for delivering burns during the scan process

question

SAR

answer

Determines energy needed to deliver a pulse, adds all pulses in sequence, divides by pulse TR to get the power. Total power is divided by pt's weight

question

mid-1977

answer

First human scanned in MR imaging

question

389, 2005, nine

answer

FDA reported ___________ incidents in ___________ and ___________ deaths. >70% were burns, and 10% were projectile-related

question

RF waves are nonionizing radiation

answer

Why MR is considered safer than radiology and CT

question

diamagnetic

answer

Reduces magnetic field. Ex: sheets, paper, plastic, equipment, or devide manufactured to be used in or around a magnetic field

question

310

answer

Between 2004 and 2008, accidents increased by _______________ percent.

question

paramagnetic

answer

Magnetic susceptibility of <1 Ex: gandolium-based contrast agents and rare earth metals such as lanthanide

question

superparamagnetic

answer

Ex: iron-containing contrast agent

question

ferromagnetic

answer

Magnetic susceptibility of >1 Ex: O2 tanks, stretchers, wheel chairs, IV poles, scissors, hemostats, floor buffers, mops, mop buckets

question

static magnetic field

answer

Main magnetic field (Bo)

question

Tesla (T)

answer

Measures magentic force and is used to describe MR magnet's field strength

question

0.2 to 3.0 T

answer

Bo ranges from:

question

30K

answer

1.5T has static field that is ___________ times stronger than earth's magnetic field

question

10K Gauss

answer

1T=

question

gauss

answer

Magnetic field around MR equipment may be measured in:

question

5-gauss line

answer

Perimeter around scanner defining where static field is potentially dangerous

question

4.0T

answer

If infant is 1 month or younger, maximum field strength is:

question

FDA

answer

_______ guidelines determine maximum field strength

question

8.0T

answer

Max field strength on humans >1 month old

question

all entrances to MR facility

answer

Warning sign should be posted on:

question

increase

answer

As magnetic field strength increases, safety risks _______________.

question

magnetic attraction or pulling force agains ferromagnetic objects

answer

Primary safety concern of static magnetic field

question

fringe field

answer

Invisible magnetic force that extends outside magnet

question

360-degree

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Magnetic fringe field is a ______________ perimeter around scanner

question

main magnet's field strength, amount of shielding inside MR scanner

answer

Factors that affect fringe field

question

passive shielding

answer

Iron beams used in room construction provide:

question

active shielding

answer

Consists of tightly wound magnetic coils that alternate electrical current to restrict magnetic field and reduce fringe exposure

question

strength of magnetic field, object's mass and distance from magnet

answer

Translational force of ferromagnetic object depends on:

question

aneurysm clips, pacemakers

answer

Examples of implanted devices

question

torque

answer

If pt with implanted device turns and walks out of room, the device could:

question

back pt out of room without turning

answer

If MR personnel discover a pt has an implanted device after he or she is taken into the scanner room, the technologist should:

question

handheld magnet, metal detector

answer

MR personnel can check to see if item is ferromagnetic using:

question

at least 10,000 gauss

answer

Strength of handheld magnet

question

RF waves

answer

Deposit energy into pt, which can increase tissue temperature

question

specific absorption rate (SAR)

answer

Measure of amout of RF energy absorbed by body

question

watts per kilogram

answer

SAR is measured in:

question

global specific absorption rate

answer

Absorption rate averaged over entire body or over a small sample volume (between 1g and 10g)

question

International Electrotechnical Commission and FDA

answer

Sets limits for whole-body and localized tissue heating

question

oscillating magnetic field

answer

RF coil produces:

question

RF pulses

answer

Transmitted into pt and excite tissues to produce signal that can be converted into image

question

manufacturer-approved MR padding

answer

Helps prevent pt's body from touching the inside wall of MR bore

question

closed-loop connection

answer

Crossing arms or legs would create a:

question

silver and silver chloride

answer

MR-approved ECG leads are made of:

question

thermal burns

answer

Imaging coils, ecg leads, looped wires, and unplugged coils can cause:

question

Pacemakers and ICDs, neurostimulation systems, halo vests and cervical fixation devices, transdermal medication patches, damaged ecg leads, pulse oximeters

answer

Implanted devices that can cause excessive heating

question

metalling object (even if it is nonferrous)

answer

RF waves can heat any:

question

permanent makeup, tattoo ink

answer

_________________ and _______________ can contain metallic flakes, and pts should be warned of skin irritation

question

gradients

answer

Used to change static magnetic field of MR scanner to produce the parameters required for various MR exams

question

three

answer

There are ____________ pairs of gradient coils

question

acoustic noise and peripheral nerve stimulation

answer

Safety concerns specific to gradients

question

acoustic noise

answer

Loud noises and vibrations created with gradient coils are turned on and off

question

FDA

answer

____________________ established guidelines on acceptable noise levels for MR scanning

question

29 dB

answer

Hearing protection devices must provide at least ____________ of attenuation

question

ACR, Guidance Document for Safe MR Practices: 2007

answer

________________ issued important MR safety information called _______________________.

question

Zones 1 through 4

answer

Guidance Document for Safe MR Practices breaks down areas of MR facility into ___________________ according to safety relative to the magnetic field.

question

Non-MR personnel

answer

Pts, visitors, staff who have not been trained

question

MR department office staff, patient aides

answer

Examples of Level 1 MR personnel

question

MR techs, radiologists, radiology dept nursing staff

answer

Examples of Level 2 MR personnel

question

detailed safety screening sheet

answer

Each person who enters the MR scanning suite must complete:

question

metalling objects on body, metallic medicinal patches, metalling or mechanical implants

answer

MR technologists must screen people for:

question

blood, urea and nitrogen, creatinine, estimated glomerular filtration rate levels

answer

If contrast is needed, pt may require lab tests to check for:

question

cancer hx, prior chemo/radiation, surgeries, pregnancy, breast-feeding, Rx allergies, MR exams, other dx exams

answer

Examples of questions on questionnaire

question

follow facility's policies and procedures

answer

If woman is pregnant or breast-feeding and contrast is ordered, tech should:

question

ACR

answer

_____________ provides guidelines on contrast media injection into pregnant pts

question

1. Remove pt from room 2. Close and lock MR scanner room 3. Activate emergency response

answer

Steps during an emergency

question

Faraday's law of induction

answer

States a changing magnetic field induces electrical voltage in any conducting medium

question

4K, -269 degrees C, -450 degrees F

answer

Cryogen temp

question

mid-1980s

answer

MRI has been used clinically since the:

question

2001

answer

When child was killed by O2 tank

question

the White Paper on MRI safety, 2002

answer

ACR Guidance Document for Safe MR Practices is known as ______________________ and was published for the first time in __________________.

question

ASTM, 2005

answer

New Terminology with Regard to MRI and Implants and Devices was published by __________________ in _____________.

question

mrisafety.com

answer

MRI safety webside by Dr. Frank Shellock

question

MR safe

answer

Item that poses no hazards in all MRI environments

question

MR unsafe

answer

Item that is known to pose hazards in all MRI environments

question

MR conditional

answer

Item that has been demonstrated to pose no known hazards in a specified MRI environment

question

static magnetic field strength, RF, gradient

answer

Item must be tested under ALL the following components for safety:

question

SAR, W/kg, temperature

answer

RF effects are measured as _____________ in units of _____________ or ________________.

question

frequency, field strength, pt size

answer

RF heating is induced within the pt and is related to:

question

100 MHz

answer

In frequencies below ___________, 90% of absorbed energy results from tissue currents induced by the magnetic component of RF field.

question

increase in body temp or SAR

answer

FDA limit for RF exposure is measured as:

question

pt's weight, pulse sequence parameters

answer

Important factors when monitoring SAR

question

conductive loops

answer

RF fields can be responsible for significant burn hazards because of electrical currents produced in:

question

gradients

answer

Used to spacially encode signal

question

peripheral nerve stimulation, magneto-phosphenes, acoustic noise

answer

Gradient effects:

question

nerves, blood vessels, muscles

answer

Act as conductors in body

question

peripheral tissues, higher

answer

Induced current is greater in ___________________________ becaue the amplitude of gradient is ___________________ away from magnetic isocenter.

question

peripheral nerve stimulation

answer

Mild cutaneous sensations and involuntary muscle contractions during echo planar techniques are known as:

question

EPI sequences

answer

Pose the greatest concern for TVMF effects

question

magneto-phosphenes

answer

Visual effects that occur when retinal phosphates are stimulated by induction from TVMF

question

current passing through gradient coils during image aquisition

answer

Causes acoustic noise

question

10-20 dB

answer

Foam earplugs can attenuate acoustic noise by:

question

quiet gradient system

answer

Anti-noise or destructive noise apparatus

question

0.6G

answer

Magnetic field strength that surrounds earth

question

magneto-hydrodynamic effect

answer

Increase in amplitude of T wave on ECG

question

cardiac gating

answer

Magneto-hydrodynamic effect can create problems with:

question

superconductive

answer

solenoidal electromagnets that have been supercooled with cryogens

question

748

answer

_____L of helium gas makes 1L of liquid

question

asphyxia, hypothermia, ruptured, eardrums

answer

Possible side effects of quench

question

translational and rotational

answer

Forces that cause ferromagnetic materials and devices to move when in proximity of a static magnetic field

question

rotational force

answer

Can cause torque on aneurysm clip

question

translational force

answer

Responsible for ferromagnetic objects being violently attracted into MR scanner

question

missile affect

answer

Ferromagnetic objects can become airborne as projectiles

question

torque, heating, artefacts

answer

Effects of metallic implants

MR Safety Zones and Energy Deposition Rates

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