Spontaneous Discharge of a Firearm in an MR Imaging Environment

Here's an interesting vid... the strength of these magnetic fields is pretty impressive
http://www.iflscience.com/health-and...ar-mri-machine

I recall an incident where a cop lost his weapon to the forces of an MRI, don't recall the gun firing. This article is dated 2002, might be the same incident.

Dumbass should be relieved of his weapon and made to pay for repairs and the cost of re-energizing the magnets.

Quote:

---

Originally Posted by Duman

I recall an incident where a cop lost his weapon to the forces of an MRI, don't recall the gun firing. This article is dated 2002, might be the same incident.

Dumbass should be relieved of his weapon and made to pay for repairs and the cost of re-energizing the magnets.

---

Do the magnets need to be re-energized?

The magnetic coils arè super-cooled with liquid helium to take advantage of copper's superconductivity at ~4K (I'll have to look it up again).

You need the superconductivity to achieve those huge magnetic fields. If you have an MRI, and have any metal in you, let the doctors know. If it's ferrous, it might get ripped out of your body the hard way.

Yeah but does it cause the magnets to be re-energized?

There are coils of superconducting ribbons arranged around the patient in an MRI. The passage of current through the ribbons creates the magnetic field. This is called electromagnetism, which is different than "ferromagnetism" that results in permanent magnets (the kind on your fridge). Passage of current through any conductor will create a magnetic field. (like copper windings in a motor)

Current on = magnetic field
More current = stronger magnetic field
Current off = no magnetic field

The superconducting ribbons pass extremely high currents, which is why the magnetic fields are so strong in an MRI. The liquid helium reduces the temperature of the ribbons to a temperature below their critical point (the temperature where they begin acting as a superconductor). The ribbons are not made of copper, though. They are made of alloys of niobium and tin or titanium (usually).

Quote:

---

Originally Posted by Duman

Dumbass should be relieved of his weapon and made to pay for repairs and the cost of re-energizing the magnets.

---

I was questioning this. If they don't need to be re-energized, then no need for paying to do so.

Gottcha

You're right, my working assumption was that you couldn't just turn off the power. The inductive kickback would be interesting to watch....from a safe distance.

Quote:

---

Originally Posted by Duman

You're right, my working assumption was that you couldn't just turn off the power. The inductive kickback would be interesting to watch....from a safe distance.

---

There is a sign before walking through a metal detector at the VA Medical Center saying that the magnet is on even though the MRI is not in use.