Magnet Safety Training Center for In Vivo Microscopy V1.4

1. Magnet Safety Training Center for In Vivo MicroscopyV1.4 Updated: May 15, 2012 • Your Magnet Safety Team • Larry Hedlund • Gary Cofer • Bastiaan Driehuys

2. General MRI Hazards • An MRI scanner creates a magnetic field that is 30,000-150,000 times stronger than the earth’s magnetic field and is always on • While hazards to people with pace-makers and implants tend to be emphasized, projectile hazards are most worrisome for us • Within a few feet of the magnet, the field gradient can rip steel objects out of your hand • The onset of this zone is very rapid and non-linear • Objects can reach speeds of 80mph before slamming into the magnet (or you) Center for In Vivo Microscopy NCRR

3. Unique Issues to CIVM • Compared to other magnet facilities like: • A clinical 1.5T MRI suite • An NMR spectroscopy facility • 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 Center for In Vivo Microscopy NCRR

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

5. Notable Observations: • Vobj =45mph at 2T • Equivalent to 7-story free-fall • Vobj =83mph at 7T • Equivalent to 23-story free-fall • Terminal velocity facts: • Scales as square root of B0 • independent of mass* • Impact energy • Scales with mass • Scales linearly with B0 How Fast Will Objects Fly? Center for In Vivo Microscopy (See appendix for math if interested) NCRR

6. Forces on Objects! B0=7T, radius=20cm • Objects can be pulled with 50-300x their normal gravitational weight • Within 1 meter of scanners tools can slip off surfaces and start accelerating • Peak force occurs roughly 10-20cm from magnet entrance

7. 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

8. 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

9. Our Magnet Policies • NO EQUIPMENT brought into lab without sign-off and Labeling by magnet safety representative • NOBODY WORKS IN THIS MRI LAB until they have completed this magnet safety training • And Documented it by signing their name on the wiki • VISITORS and AFTER HOURS WORK have separate policies Center for In Vivo Microscopy NCRR

10. 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

11. 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 requires written permission from the Center Director • It is advisable never to bring any magnet hazards into the lab after hours • No visitors are allowed in the MRI labs after hours.

12. 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

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

14. 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) Center for In Vivo Microscopy NCRR

15. A recent incident (Jan 2011) Rigging required to remove pump from 7T • 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

16. What went wrong? • Despite a 5yr magnet safety training program at CIVM, the visitor had not completed the training. • The object he brought in to 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

17. 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 Buffer Stuck to 7T

18. What went wrong? • Janitor had gotten close to Bruker 7T, and 2T without problems • Assumed the 7T in rm 141 would be the same • But the 7T in room 141 is UNSHIELDED • What can you do? • Be ware that the reach of the 7T in rm 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

19. Fact Review • Ferrous objects are our biggest hazard • Objects can reach 45mph in the 2T magnet and 83mph in the 7T magnet • 1 meter from magnets, the magnetic force becomes equal to gravitational force • Objects can be pulled (accelerated) with 50-300x their normal gravitational pull • Labeling and your vigilance are our best defense against a serious accident Please sign/date training record on the Magnet Safety Wiki page to verify that you have completed this Center for In Vivo Microscopy NCRR

20. Appendix for Physicists and Engineers

21. 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

22. Projectile Velocity Estimates Conserve Energy • Notable Observations: • Vobj =45mph at 2T • Equivalent to 7-story free-fall • Vobj =83mph at 7T • Equivalent to 23-story free-fall • Terminal velocity facts: • Scales as square root of B0 • independent of mass* • Impact energy • Scales with mass • Scales linearly with B0 Treat object as iron chunk: Velocity scales as sqrt(B0) Center for In Vivo Microscopy NCRR

23. Gradient Spatial Profile Estimates a B z B0=7T, radius=20cm Force in field gradient Estimate scanner as dipole loop Gradient from dipole loop Peak gradient strength • Peak gradient at roughly 10-20cm from edge of scanner • Peak gradient strength proportional to B0 and inverse of bore size Center for In Vivo Microscopy NCRR

24. Forces! B0=7T, radius=20cm Force on object Point where magnetic force = gravitational force • Within 1m of scanners tools can slip off surfaces and start accelerating into the magnet • Objects can be pulled with 50-300x their normal gravitational weight at peak gradient point Center for In Vivo Microscopy NCRR