MRI Safety: Exam 2

Zone II

Unscreened MRI patients: the MRI environment where patients are unable to move around freely and are supervised by MRI personnel.

Fringe field/flux lines

- The closer to the center of the magnet (isocenter) the stronger the fringe field. - Ferrous objects will have to be kept further away in the 3T. -All ancillary equipment entering the MR room must have a green label. -No patient should be within the MR scanner or flight path when any equipment is brought into Zone IV (MR room).

Quench: how it works

-A superconductive magnet loses its superconductivy releasing its stored energy in its main coil as heat, and boils off the magnet reservoirs of gases. INDICATIONS: -Loud noise - warning on the system scanner requesting you remove patient immediately. - of vent fails, quench becomes hazardous resulting in the scan room being filled with a white cloud of cryogen vapor -you must evacuate the patient and all personnel from the room failure to do so can result in: asphyxiation, frostbite, hypothermia, ruptured ear drum

Patient/ personnel screening

-Access to Zone III is restricted with out permitted badge access to escort from MRI staff. -Prior to access a personal screening form must be filled out. -All forms can be located within the MRI department and online.

Fire

-All extinguishers will be non-ferrous within the MRI department. (Note MR compatible labels) -MR staff will respond following clinical sites fire safety policy -R.A.C.E. - if fire is in the scan room and the fire department has to access the room the magnet has to be quenched to avoid injury or damage to anyone in the room. - if fire is in MRI department, the scan room doors will be locked following patient evacuation. This will avoid potential injuries or damage to facilities or fire personnel.

Who is involved with patient safety?

-All students and employees. -All must follow safety protocols.

5 Gauss Line

-Area near the magnet at which the field becomes dangerous. -Varies in each Magnet room depending on the shielding around the magnet and field strength. -Should be marked in the MR room (some out patient facilities may not have this line).

RF Coils- antennae effects

-Can be responsible for significant burn hazards due to the electrical currents produced in conductive loops. -Tissue and clothing could ignite by un-insulated cables. -Coupling of transmitting and receive coils may cause severe thermal injury. -Ancillary equipment brought into the room can/will interfere.

Equipment labeling

-Pay attention to all safety labels to know what zone equipment can and can't be in, never assume that things are safe to bring in. -make sure patients are screened and are aware that ferromagnetic objects are not safe in the MR room because these projectiles can suddenly move with great force (missile effect). -SMRT- safety website

Safety Policy and Procedure

-Pertains to all people coming in proximity to the MRI system including patients, visitors, house staff, students, environment services personnel, service personnel and facilities management personnel. -The MRI environment to be regulated is designated according to the American College of Radiology Zones

Preventing MR related burns

-Position properly -Avoid direct contact with the surface of the bore, or RF surface. -Use only approved RF coils, position the cables down the center and directly out of bore. -Do not loop or cross cables -Be sure all unsafe monitoring devices and cables are removed.

The MRI technologist

-Primary responsible to oversee safety of the MRI Scan Room and immediate environment (Zone III and IV). -No one can enter the scan room without proper screening and preparation. -The MRI tech is supported in this role by the supervisors, MRI Manager and Radiologist. I

Environmental Security

-Safety depends on everyone knowing their part: following MRI safety policies and procedures/guidelines. -Policies and procedures for the MRI section are established by the medical director of MRI in coordination with the Administrative Director.

Non-personnel with implantable devices

-The MR technologist must document and initial that the contraindication was noted but safety was assessed and approved for entering the scan room. -The radiologist will confirm the safety of any implanted device when safety concerns arise before the individual enters the MR unit.

B1RF

-We use radiofrequency for the processional frequency of each image. -Coils are big antenna for signals that are there, for every coil we need to know each limitation.

Temporary Transferring Patients

-When patients require non-MRI safe equipment to be stationed in Zone III or IV (i.e. respirator) it will be supervised by the MRI technologist and their designee (nurse, resp. Therapist, etc.) -The designee must verbally attest by signature documenting their understanding of MRI Safety Concerns and their acceptance of responsibility for their supervisory role.

Static magnetic fields

-You cannot see them but they exist. -Distance matters -Must be very careful of what items are brought in, what items are surgically implanted, and what your history is working with metal.

Laser lights

-a semiconductor laser alignment light is used for patient land marking. -laser lights could cause eye injury -instruct patient to close eyes during land marking.

Quenching the magnet

-do not panic -tech uses intercom to communicate with patient -set up ventilation: exhaust fan -help patient out the door -evacuate all personnel IMPORTANT: -only use in life or death situations: large ferromagnetic object is pinned against the magnet and no other method can prevent further injury or free the object. -two push buttons: control room and MR suite - pressing this switch will cause helium to vent from the magnet, through the ceiling portal. All patients and staff must evacuate the MRI scan room immediately.

Magnetic field/ Scan room emergencies

-each magnet has two emergency buttons 1. Emergency stop/shut off: turns off all incoming electrical power to the magnet power distribution. 2. Quench or Emergency run down: causes immediate collapse of the superconductive magnetic field within minutes -these buttons shouldn't be depressed without being instructed by an MRI staff member, due to an emergency.

1. B0Static magnetic fields

-ferromagnetic objects.

Medical emergencies in MRI

-immediately remove the patient from MR scan room and secure doors -begin resuscitation -a MRI technologist, trained MRI technical assistant and/or radiologist are the gate keeper of Zone IV at all times during this emergency to ensure no one or thing enters

What is the noise?

-magnetic field gradient -noise occurs during rapid alterations of currents within the gradient coils. -noise is produced when the forces cause motion or vibration of the gradient coils as they impact against their mountings, which flex or vibrate. -remember, stronger magnets with stronger and faster gradients will be louder

3. Gradients

-time varying magnetic field effects, noise, peripheral nerve stimulation, magnetophosphene. -TVMF (time varying magnetic field) health concerns with nerves, blood vessels, and muscles because they act as conductors in the body. -patient must not clasp hands or feet. -noise produced by gradients can cause hearing damage, people in Zone IV must use hearing protection.

3 areas of safety (3 bucket approach)

1. BoStatic magnetic fields 2. B1RF: frequency; coils picks up all signals 3. Gradients: time varying magnetic field effects, noise, peripheral nerve stimulation, magnetophosphere.

"Red label"

All equipment with this label are NOT MR safe.

"Green MR" label

All equipment with this label is deemed safe for Zone IV.

2. B1RF

Coils and heating of tissue or burns.

A Sentinel Event

Defined by The Joint Commission (TJC) as any unanticipated event in healthcare setting resulting in death or serious physical or psychological injury to a patient/patients, not related to the patients illness.

Non-life-threatening emergency

Emergency stop/ shut off button -fire in the computer room - fire, sparks, loud noises emanating from the scan room -flooding or sprinkling system goes off -catastrophic equipment failure -the MR system has emergent stop/shut off controls in/ out of the room, when needed these buttons can be depressed as a safety mechanism. -remember the magnet is still on

Zone I

General public: any area outside the MRI environment where staff and patients can move freely.

Projectiles

Objects brought into the room that are made of ferromagnetic metals will be pulled by the magnet of the scanner.

Potential catastrophes

Prevention: -The immediate area around the MR systems is clearly demarcated with appropriate multilingual warning signs. -No ferromagnetic O2 tanks are permitted in the MRI corridor (Zone III or IV). -Trained MR staff will secure the entire area. -All individuals entering the magnetic field will he carefully evaluated and screened

Zone II and Zone III

Restricted access: -during operating hours,access doors between Zone II and Zone III will be kept closed at all times -the MRI receptionist staff will regulate access through these doors.

Zone IV

Screened MR patients: under constant supervision of trained MR personnel. -Restricted access: scan room doors remain closed at ALL times, except when moving patients in and out of the room and while patient contrast injections are ongoing.

Zone III

Screened MRI patients and personnel: access to this zone is strictly restricted and controlled/supervised by MR personnel. Restricted Access: -security is responsible for maintaining a list of personnel permitted to have badge access to the fire egress door, which is controlled by hospital staff badges. -The front entrance and the MRI scan room doors will remain locked when department is closed.

The missile effects

The capability of the fringe field component of the static magnetic field to attract ferromagnetic objects (I.e. oxygen tanks, tools, monitors, anesthesia carts, etc.) that may be subsequently drawn into the MR system by considerable force.

"Yellow label"

This equipment has been tested in all different field strengths. ex: Equipment could be safe in scan room with a 1.5T machine but not safe in a scan room with a 3T machine.