Transcript Safety in the Magnetic Resonance Environment

MRI Safety
This slide show will educate all healthcare providers about the
safe delivery of care in the magnetic resonance (MR) environment.
This slide presentation has been adapted for Nursing
from an original presentation compiled by:
Deborah Schwengel, M.D.
Christopher Pressley, M.D.
Kaadze Wright, M.D.
Robert W. Evers, BSRT, MR, CV
THE MAGNETIC FIELD
IS AT FULL POWER
ALWAYS ….IT IS
ALWAYS “ON”.
EMPLOYEE SAFETY
ALL EMPLOYEES MUST BE SCREENED
TO WORK IN A MAGNETIC FIELD
ENVIRONMENT JUST LIKE THE
PATIENTS.
NO EXCEPTIONS.
MRI PROCEDURE SCREENING FORM
To ensure patient safety, completion of the
MRI screening form is required prior to every
MRI scan. Units can assist & expedite the
MRI's triage process by completing this form in advance
and faxing to 2-8582.
This form is located online at:
http://www.rad.jhmi.edu/requisitions.htm
MRI Screening Sheet
All Patients will need
this form filled out
before an MRI can be done.
Ideally, the form should be
filled out by:
a. The Patient
If the patient cannot fill it out:
b. Family Members
If there are no family members:
c. Referring MD
What to do in an Emergency
• If there is a Patient Emergency in MRI…
– GET THE PATIENT OUT OF THE ROOM
– NO CODE OR CODE LIKE PROCEDURES
WILL BE RUN IN THE MRI ROOM.
BURNS
• It is “possible” for patients to get 1st, 2nd, or
even 3rd degree burns in an MRI if items
such as ECG cables are looped and are
touching the patients skin (even if these
devices are MRI compatible).
– All “cables” should not touch the patients skin
directly, and should NOT be in a LOOPED
configuration.
What can you take into a magnetic
field?
• ONLY ITEMS THAT ARE MRI
COMPATIBLE. Such as…
– Brass
– Aluminum
– Plastic
– IF YOU ARE NOT SURE IF AN OBJECT
IS MRI SAFE…DON’T TAKE IT INTO
THE ROOM. ASK A
TECHNOLOGIST!!!!!!!!
Magnetic Field
• What “objects”
can you take into
a magnetic field?
Anything that doesn’t contain
iron.
To be safe…TAKE NOTHING
INTO A MAGNETIC FIELD.
Work closely with the
Technologist who works in
that type of environment
each day. Question Everything.
Site Access Restriction:
Screening
• All patients presenting for a non
emergent scan must be screened by
two MR personnel, including one with
level 2 qualifications.
• A detailed history on possible implants
or metallic objects must be obtained in
writing and signed by appropriate
medical licensed personnel.
• Do not rely on verbal history alone.
Characteristics of the
Magnetic Field
• the force of the field is measured in tesla (T); a typical
scanner is approximately 1.5- 3.0 tesla
• the force of the field is greatest at the periphery
of the magnet. This FORCE INCREASES as you
move closer to the magnet.
• NOT ALL MAGNETS ARE THE SAME FIELD
STRENGTH, THUS THEIR “ATTRACTIVE FORCES”
WILL BE DIFFERENT.
Biologic Effects of the Static Magnetic
Field on Persons in its Proximity
questions to consider
• does the field have long term deleterious effects such
as increasing the risk of neoplasm?
• does the field have effects on the patient which alter
our monitoring?
• does the field have effects on implanted medical
devices which are non-ferromagnetic and “MR safe”?
To date there is no clear and
convincing evidence that
exposure to high magnetic
forces in the MR environment
increases the risk of cancer.
Effects of the Static Magnetic
Field on Implanted Medical
Devices
Although certain devices such as
implanted pumps may be MR
compatible, there are still important
considerations in this patient
population.
Determining if a medical
device is safe in the MRI
environment
• The MRI staff are always equipped with
the latest information on device safety.
• Questions should be directed to the
chief MRI technologist.
Pacemakers
There several reports in the literature
describing the occurrence of sudden
death in the MR for patients with
implanted (but MR compatible) pacers.
To date the mechanism of these
fatalities is unclear but is thought to be
secondary to the induction of fatal
arrythmias. Therefore pacemakers are
currently a contraindication to MR
scanning.
Forces in the MR Environment
• Magnetic field
– missile effect: TRANSLATION
– rotational effect: ROTATION/TORQUE
Translational Force
• this term describes the force which attracts ferrous
objects to the center of the magnetic field
• may act to transform ferrous objects into missiles as
they accelerate toward the magnet
• the force is greatest when the difference in field
strength across the object is greatest; where delta T
or difference in field strength from point A to point B is
maximized
A
B
Rotational Force
• this force relates to the North - South orientation
of the scanner’s magnetic field
• ferrous objects will attempt to align their long
axes with this orientation
• this force will rotate objects until they are aligned
and is greatest at the very center of the field
(unlike the translational force which is greatest
where the difference in magnetic field across the
object is greatest)
Another danger in MRI QUENCH!
• MR scanners are supercooled with inert gases such as
helium.
• If these cryogens BOIL OFF either intentionally or
unintentionally, a quench has occurred. THIS IS
EXTREMELY BAD.
• An INTENTIONAL quench is done in an emergency to run
the magnetic field to ZERO in order to remove a
projectile/patient from the scanner in extreme emergencies.
• If a quench occurs, remove all staff from the room
immediately
Another danger in MRI QUENCH!
• THE WORRY WITH A QUENCH IS THE
POTENTIAL FOR ASPHIXIATION AND
FROST-BITE TO THE HEALTH CARE
WORKER AND PATIENT.
Pregnant Patients or
Personnel:
• Pregnant patients regardless of
trimester are only scanned if the results
of the study will change the care of the
patient.
• Pregnant MR personnel are encouraged
not to stay in the room during the
scanning process.
Introduction to the zone
system for maintaining safety
in the MRI suite
Site Access Restriction
– All personnel with access to MR must have
either level 1 or level 2 qualifications.
– Level 1 personnel are minimally trained in
MR safety and can ensure their own safety
and the safety of a patient in the MR
environment.
– All JHH anesthesiologists must have level 1
qualifications.
Site Access Restriction
• Level 2 personnel are extensively
knowledgeable about the MR
environment, the potential hazards of
the agents and equipment used, and
MR safety precautions.
• The MR safety director, and all MR
radiology technologists are level 2
personnel.
Safety Zones
• Zone 1 : This is a public access area with
no restrictions.
• Zone 2 : This is a semi restricted area
where patients and hospital staff can
interact.
• Zone 3 : This area is completely physically
restricted from non MR personnel
especially the general public.
Remember this mnemonic:
MRI =
Metal Results (in) Injury
The End