Magnet Safety Training Center for In Vivo Microscopy V1.5 Your Magnet Safety Team Gary Cofer Bastiaan Driehuys Updated: April 11, 2016

Center for In Vivo Microscopy NCRR General MRI Hazards always on An MRI scanner creates a magnetic field that is 30, ,000 times stronger than the earth’s magnetic field and is always on projectile hazards While hazards to people with pace-makers and implants tend to be emphasized, projectile hazards are most worrisome for us rip steel objects Within a few feet of the magnet, the field gradient can rip steel objects out of your hand very rapid The onset of this zone is very rapid and non-linear 80mph Objects can reach speeds of 80mph before slamming into the magnet (or you)

Center for In Vivo Microscopy NCRR Unique Issues to CIVM We have the following differences: Higher field strengths than clinical (7T vs. 1.5T) –Force on objects scales with field strength Larger magnet bores than NMR spectroscopy –The magnet “reach” scales with bore size Equipment and tools used in MRI suite –Providing a handy supply of magnetic projectiles Compared to other magnet facilities like: A clinical 1.5T MRI suite An NMR spectroscopy facility

Center for In Vivo Microscopy NCRR Why Bother With Magnet Safety? serious injury or death A magnet projectile presents a very real possibility of serious injury or death system down time Impact of the magnet by a projectile could result in 3 months of system down time less money Repair costs leave less money for science –$450,000 to replace a 7T magnet –$20k, to ramp one down and back up onerous safety rules and less science Serious incidents lead to more onerous safety rules and less science

Center for In Vivo Microscopy NCRR How Fast Will Objects Fly? (See appendix for math if interested)

Forces on Objects! B 0 =7T, radius=20cm

Center for In Vivo Microscopy NCRR CIVM Incidents and Hazards Peristaltic Pump stuck to 2 Tesla magnet Chair stuck to 7T magnet Surgical tools ripped from ventilator cart, stuck to 7T magnet Compressed nitrogen tank stuck to 2 Tesla magnet Fan stuck to 2 Tesla magnet Hand-tools stuck to 7 Tesla magnet Other Hazards: motors, power supplies (in all electronics), drill bits, cylinder caps, razor blades, screws

Center for In Vivo Microscopy NCRR Personal Safety and Nuissances Persons with pace makers and infusion pumps should consult their physician before working in this laboratory Remove watches, wallets, and cell phones before entering laboratory Most jewelry (gold, silver, diamond) is safe in the magnet environment

Center for In Vivo Microscopy NCRR Our Magnet Policies 1. NO EQUIPMENT brought into lab without Labeling appropriately for magnet hazard status 2. NOBODY WORKS IN THIS MRI LAB until they have completed this magnet safety training – And documented it by signing their name on the Wiki 3. VISITORS and AFTER HOURS WORK have separate policies

What About Visitors? Visitors may enter the MRI lab only when accompanied by trained CIVM personnel –Instruct visitors briefly about MRI hazards Visitors must stay at least 10 feet away from magnets (close to the door is good) Visitors may never assist or work in the lab Visitors may not enter the lab after hours

Weekends and After Hours The magnet laboratories are available from 7:30 AM to 5:00 PM Monday through Friday. Use on nights or weekends should be done only by CIVM personnel. It is advisable never to bring any magnet hazards into the lab after hours No visitors are allowed in the MRI labs after hours

Center for In Vivo Microscopy NCRR Working with Magnet Hazards Ensure the magnet hazard has been labeled Ensure that someone else is present when you move a magnet hazard in the lab When moving a magnet hazard don’t get between it and the magnet

Center for In Vivo Microscopy NCRR Labels Used in Our Lab Labels are on clipboard by 2T console. To print more, see Magnet Safety Page on Wiki

Center for In Vivo Microscopy NCRR If You Do Get Something Stuck Evacuate the lab Seek medical help (if appropriate) Contact magnet safety team member for removal of object (Get a camera and take a picture, so we can update this presentation)

A recent incident (Jan 2011) Situation: Senior Scientist (MRI professor) visiting CIVM Had worked at CIVM many times in the past Carried motor/pump close to 7T before it was ripped from him Assumed it was safe because advertised as “MR-compatible” Motor/pump stuck to 7T Rigging required to remove pump from 7T

What went wrong? Despite a 5-yr magnet safety training program at CIVM, the visitor had not completed the training. The object he brought into the lab had not been screened for magnetic content and had not been labeled as being a magnet hazard. (Evan was not the guilty party) What can you do? Don’t be shy about asking anybody you see in the magnet lab if they have completed our magnet safety training. Be vigilant about possible magnet hazards. If they are needed in the lab, make sure they are labeled as hazards.

Another recent incident (April 2012) Situation: Janitor working on buffing floors Received instruction to stay away from magnet Still got buffer sucked into the magnet Janitor’s Floor Buffer Stuck to 7T

What went wrong? Janitor had previously gotten close to Bruker 7T and 2T without problems Assumed the 7T in room 141 would be the same But the 7T in room 141 is UNSHIELDED What can you do? Be aware that the reach of the 7T in room 141 reaches 10x further than the Bruker 7T (16ft reach vs. 1-2 ft reach) Our current safety presentation is geared towards scientists. We need another solution for non-scientists. Need a Visceral Poster for Non-Scientists.

Center for In Vivo Microscopy NCRR Fact Review Please sign/date training record on the Magnet Safety Wiki page to verify that you have completed this

Appendix for Physicists and Engineers

Center for In Vivo Microscopy NCRR How Fast Will Objects Fly? Potential Energy of Object Stuck in Magnet Potential Energy of Object Removed from Magnet Difference must be kinetic energy prior to impact

Center for In Vivo Microscopy NCRR Projectile Velocity Estimates Conserve Energy Treat object as iron chunk: Velocity scales as sqrt(B 0 )

Center for In Vivo Microscopy NCRR Gradient Spatial Profile Estimates Estimate scanner as dipole loop Gradient from dipole loop Peak gradient strength ware 0 =7T, radius=20cm Force in field gradient a z BB 1.Peak gradient at roughly 10-20cm from edge of scanner 2.Peak gradient strength proportional to B 0 and inverse of bore size

Center for In Vivo Microscopy NCRR Forces! Force on object B 0 =7T, radius=20cm Point where magnetic force = gravitational force 1.Within 1m of scanners tools can slip off surfaces and start accelerating into the magnet 2.Objects can be pulled with x their normal gravitational weight at peak gradient point