fmrilevel1 Flashcards
(26 cards)
what is the 5 gauss magnetic field line?
safety boundary
when you enter magnet room, you’re in an area with a magnetic field of 5 Gauss or greater
bounded by magnet room
What does it mean to be in an area w/ magnetic fields of 5G or greater?
implants/inclusions will be affected
metallic objects electronic devices in body might malfunction or twist, leading to death or injury
outside body, will become projectiles and potentially cause sever injury/death
items not allowed in scanning room
belt, coins, necklaces, piercings, rings, watch, pens, keys, credit cards (!), eyeglasses, cell phone, any electronic device, belly button rights, vena cava umbrella, back brace, etc
transport trolleys, traction devices, gas tanks, etc
any thing magnetizable
check w/ meta detector wand and walk-through metal detector to be sure there are no metal objects
medical conditions disqualifying from entering magnet room
injury for metallic object or foreign body or from metal work, pregnancy, aneuryism clip, cardiac pacemaker, eletronic implant/device; cochlear, otologics, or other ear implant; spinal cord stimulator; any type of prosthesis, heart valve prosthesis, artificial or prosthetic limb, metallic stint, joint replacement (hip, knee)
when is the magnetic field off?
it is always on
who is responsible for people allowed in scanning area?
me
liquid helium
used daily as coolant for magnet; could displace oxygen in room if escaped
situations in which helium could escape
magnet quench, broken pipe
in the even tof helium release
evacuate scanner room immediately and activate emergency exhaust button to ventilate the helium from teh scanner room
oxygen monitor levels
If below 18%, warning lights. 14% sound alarm. 11% breathing is difficult.
15-19.5% oxygen
decreased ability to work strenuously, impaired coordination, induced symptoms in thise w/ coronary or pulmonary or circulatory problems
12-15% oxygen
respirationd eepns, increased pulse rate, impaired coordination, perception, judgment
10-12% oxygen
Further increase in rate and depth of respiration, further increase in pulse rate,
performance failure, giddiness, poor judgment and blue lips.
8-10% oxygen
Mental failure, nausea, vomiting, fainting, unconsciousness, ashen face, blue lips.
5-8%
8 minutes may be fatal in 50-100% of exposures; 6 minutes may be fatal in 25-50%
of exposures; 4-5 minutes, recovery with treatment.
4-6%
Coma in 40 seconds, convulsions, respiration ceases, death.
oxygen monitor location
in console room near door
emergency power shutdown button
turns off all MR hardware including host computer. Does not turn off magnetic field.
emergency power shutdown button locations
1) right of viewing window in skyra control suite (left of quench button)
2) left of door as you walk into machine room
3) right on wall as you walk into skyra magnet room
magnet quench
only use if an emergnecy siutation for persons in magnetic field exists.
Examples: magnet attracted large piece of metal, person caught between it and magnet, and 1 person can’t remove it easily; a thin piece of metal has been attracted by magnet and caused serious injury
Not when no one is in danger. Instead start by contacting someone on emergency list, emailing mrihelp@princeton.edu etc. Siemens if no one answers.
what happens when magnet quenched
Liquid helium, used to cool the magnet, is vaporized and reeased via exhaust line. Rise in temperature in magnet causes coils to lose superconductivity and field strength rapidly falls.
helium is released, displacing oxygen is scanner room. This causes oxygen content in room to drop really low, and death by asphyxiation can occur. Helium droplets may form on exhaust vent lines that coudl cause frostbite if touched.
serious damage may result to magnet, making further use impossible until a technician comes to return it to service.
locations of magnet quench
in console room to right of monitors, and in magnet room to right of door when you walk in.
Each protected by plastic door and yellow sticker to prevent acccident.
emergency exhaust button
immediately after magnet is quenched or pipe has broken, allowing helium to be lrelaesed and increase oxygen flow.
Located to right of oxygen monitor in skyra room
procedure for non-medical emergency
abort scan, emergency shutdown button, help subject out and evacuatte scanner area, call public safety (609-258-1000) and specify location of emergency, contact someone on emergency contact list
