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ND in an MRI

Evil Ernie

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Found this on the Hi Point forum...Long read, but still a good one. I wonder who's doing their research....1991A1?!?!?!? BLASPHEMER!!!!!!!!!!!

http://www.ajronline.org/cgi/content/full/178/5/1092

[size="+2"][font="arial, helvetica"]Introduction [/font][/size]
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Introduction
Case Report
Discussion
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An incident recently occurred at an outpatient imaging center[sup] [/sup]in western New York State, in which a firearm spontaneously[sup] [/sup]discharged in a 1.5-T MR imaging environment with active shielding.[sup] [/sup]To our knowledge, this is the first documented case of such[sup] [/sup]an occurrence. The event confirms previously reported theoretic[sup] [/sup]risks of a firearm discharging in an MR imaging environment [1].[sup] [/sup]In this report, we examine the incident in detail from the official[sup] [/sup]police and ballistic reports.[sup] [/sup][align=left][size="-1"][font="arial, helvetica"] Top
Introduction
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Case Report
Discussion
References
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An off-duty police officer went to an outpatient imaging center[sup] [/sup](not affiliated with our institution) in western New York State[sup] [/sup]to have an MR imaging examination. The facility housed a 1.5-T[sup] [/sup]MR unit (Signa; General Electric Medical Systems, Milwaukee,[sup] [/sup]WI) with active shielding. The officer was carrying a model[sup] [/sup]1991 A-1 compact.45 caliber semiautomatic pistol (Colt's Manufacturing,[sup] [/sup]Hartford, CT).[sup] [/sup][/align] The officer notified the technologist that he was carrying the[sup] [/sup]weapon before entering the MR dressing room. The technologist[sup] [/sup]told the officer to take the gun with him. The technologist[sup] [/sup]intended to meet the officer in the MR patient waiting area[sup] [/sup]before the examination and secure the weapon in that room, where[sup] [/sup]he felt it would be safe. However, the officer apparently misunderstood[sup] [/sup]and took the gun into the MR suite. The technologist was entering[sup] [/sup]the officer's personal data into the computer and did not see[sup] [/sup]him entering the MR suite.[sup] [/sup]
Once the officer was inside the MR suite, the gun was pulled[sup] [/sup]from his hand as he attempted to place the gun on top of a cabinet[sup] [/sup]3 ft (0.9 m) away from the magnet bore. The gun was immediately[sup] [/sup]pulled into the bore, where it struck the left side and spontaneously[sup] [/sup]discharged a round into the wall of the room at the rear of[sup] [/sup]the magnet. Fortunately, no one was injured. Although the gun struck[sup] [/sup]the magnet bore, only minimal cosmetic damage occurred to the[sup] [/sup]magnet itself. The MR unit had full functional capability immediately[sup] [/sup]after the gun discharged. The weapon's thumb safety was reportedly[sup] [/sup]engaged when the gun discharged.[sup] [/sup]
An unsuccessful attempt to remove the gun from the magnet resulted[sup] [/sup]in the gun being pulled to the right side of the magnet (Fig. 1).[sup] [/sup]The decision was then made to power down the magnet to remove[sup] [/sup]the gun.[sup] [/sup]
[align=left] Fig. 1. Photograph shows gun (arrow) stuck on right side of MR imaging magnet bore. [/align]
[sup] [/sup] Examination of the weapon by a ballistics laboratory concluded[sup] [/sup]that the force of the magnetic field was responsible for the[sup] [/sup]firearm's discharge. To understand how the gun discharged requires[sup] [/sup]a brief discussion of the firing mechanics of the Colt 1991[sup] [/sup]A-1.45 caliber pistol and the weapon's safety mechanisms [2].[sup] [/sup]When the weapon is normally fired, the trigger is pulled, which[sup] [/sup]releases the sear. The sear, in turn, releases the hammer. The[sup] [/sup]hammer then moves forward to strike the firing pin, which moves[sup] [/sup]forward to strike the primer of the chambered round.[sup] [/sup]
The Colt 1991 A-1 pistol has three safety mechanisms (Fig. 2A,2B,2C,2D), including[sup] [/sup]a thumb safety, grip safety, and firing pin block. The thumb[sup] [/sup]safety locks the sear in place and prevents the hammer from[sup] [/sup]moving forward when the trigger is pulled. The thumb safety[sup] [/sup]also locks the slide in place. The thumb safety is the weapon's[sup] [/sup]only active safety mechanism; it must be turned on in order[sup] [/sup]to work. The grip safety is located at the back of the gun handle[sup] [/sup]and prevents the trigger from being depressed. The grip safety[sup] [/sup]is a passive mechanism; it is always on unless deactivated.[sup] [/sup]To deactivate it, the grip safety must be depressed at the same[sup] [/sup]time the trigger is depressed; otherwise, the trigger cannot[sup] [/sup]be pulled. The firing pin block is a small metal block, approximately[sup] [/sup]the size of a pencil eraser, that sits in the firing pin channel and[sup] [/sup]prevents the firing pin from moving forward. The firing pin[sup] [/sup]block is held in place by a small spring. When the trigger is[sup] [/sup]pulled, a series of levers cam the firing pin block up into[sup] [/sup]its own well within the slide to allow the firing pin to move[sup] [/sup]freely within its channel.[sup] [/sup]
[align=left] Fig. 2A. Photographs of 1991 A-1.45 caliber semiautomatic pistol (Colt's Manufacturing, Hartford, CT). Actual gun involved in incident is shown.[align=left] Fig. 2B. Photographs of 1991 A-1.45 caliber semiautomatic pistol (Colt's Manufacturing, Hartford, CT). Muzzle of gun shows small amount of white paint (arrow) where gun impacted magnet.[align=left] Fig. 2C. Photographs of 1991 A-1.45 caliber semiautomatic pistol (Colt's Manufacturing, Hartford, CT). Hammer, thumb safety, and grip safety of gun are shown. Gun is in cocked and locked position with hammer cocked and thumb safety turned on to prevent hammer from striking firing pin. This is condition in which gun was recovered from magnet.[align=left] Fig. 2D. Photographs of 1991 A-1.45 caliber semiautomatic pistol (Colt's Manufacturing, Hartford, CT). Disassembled gun with view of slide interior from below shows firing pin block. [/align]
[sup] [/sup] [sup] [/sup][/align] [sup] [/sup][/align] [sup] [/sup][/align] At the time the weapon discharged, it was reportedly in a cocked[sup] [/sup]and locked position; that is, the hammer was cocked and the[sup] [/sup]thumb safety was engaged to prevent the hammer from striking[sup] [/sup]the firing pin. A live round was in the chamber. (Many people[sup] [/sup]who choose this weapon for personal protection will carry it[sup] [/sup]in this manner because it allows them to quickly fire the weapon[sup] [/sup]if needed.)[sup] [/sup]
When the firearm was removed from the magnet, the gun was still[sup] [/sup]in a cocked and locked position. An empty cartridge was found[sup] [/sup]in the chamber. The presence of an empty cartridge in the chamber[sup] [/sup]is highly unusual. If the thumb safety were not engaged and[sup] [/sup]the weapon fired normally by depressing the trigger, the normal[sup] [/sup]backward recoil of the slide should have automatically ejected[sup] [/sup]the empty cartridge, and a new live round should have automatically[sup] [/sup]been chambered. As discussed earlier, the thumb safety performs[sup] [/sup]two functions: it prevents the sear from releasing the hammer,[sup] [/sup]thereby preventing the hammer from striking the firing pin;[sup] [/sup]it also locks the slide in place, preventing retrograde motion[sup] [/sup]of the slide and automatic ejection of the empty cartridge. Thus,[sup] [/sup]the presence of an empty cartridge in the chamber confirms that[sup] [/sup]the thumb safety was engaged at the time the gun was fired.[sup] [/sup]Given that the thumb safety was engaged when the gun discharged,[sup] [/sup]it is also likely that the normal trigger and hammer mechanism[sup] [/sup]of firing the gun was bypassed because the thumb safety would[sup] [/sup]have also prevented release of the hammer.[sup] [/sup]
The gun likely discharged as a result of the effect of the magnetic[sup] [/sup]field on the firing pin block. The firing pin block was probably[sup] [/sup]drawn into its uppermost position by force of the magnetic field.[sup] [/sup]The firing pin block has to overcome only light pressure from[sup] [/sup]a relatively small spring to release the firing pin. The pistol[sup] [/sup]was likely drawn into the magnetic field so that the muzzle[sup] [/sup]struck the magnet's bore first. With the firing pin allowed[sup] [/sup]to move freely in its channel, the force of the impact on the[sup] [/sup]muzzle end was sufficient to cause the firing pin to overcome[sup] [/sup]its spring pressure and move forward to strike the primer of[sup] [/sup]the chambered round.[sup] [/sup]
This account explains how the weapon discharged when the thumb[sup] [/sup]safety was engaged.[sup] [/sup]
The presence of an empty cartridge in the chamber explains why[sup] [/sup]the gun did not discharge a second time when it was moved from[sup] [/sup]the left to the right side of the bore. Even if the identical[sup] [/sup]forces were repeated, an empty cartridge, not a live round,[sup] [/sup]was in the chamber at this time.[sup] [/sup]
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Introduction
Case Report
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Discussion
References
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In this incident, the gun discharged despite the thumb safety[sup] [/sup]being engaged. This has important implications in that it shows[sup] [/sup]that the weapon poses a risk for discharging in an MR imaging[sup] [/sup]environment even with the thumb safety engaged.[sup] [/sup][/align] One can look at the sequence of events preceding the discharge[sup] [/sup]of the weapon and see several points at which the incident could[sup] [/sup]have been prevented. When the officer came in with the gun,[sup] [/sup]it should have been immediately secured in a safe location,[sup] [/sup]even before the officer changed for the examination. The technologist,[sup] [/sup]knowing the officer had a firearm, should have instructed him that[sup] [/sup]under no circumstances could he bring the weapon into the MR[sup] [/sup]suite. Also, the technologist should have been monitoring the[sup] [/sup]officer more closely to make sure he did not enter the MR suite[sup] [/sup]with the weapon. Signs should have been posted at that site,[sup] [/sup]if they were not already there, warning the public of the dangers[sup] [/sup]of approaching the magnetic field of the MR imager with implants, metallic[sup] [/sup]devices, or objects such as firearms.[sup] [/sup]
In light of this incident, all radiologists should reexamine[sup] [/sup]our own site's screening methods to ensure that steps are implemented[sup] [/sup]to prevent such a situation from ever recurring.[sup] [/sup]
 

compmanio365

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Hehe, read this over on the Hi Point forum too.......what a tool for bringing his gun into an MRI......no noticing the HUGE signs saying "No metal objects"? He couldn't even claim he thought his gun was plastic, since he wasn't carrying a Glock. :p

But it does prove just how safe the 1911 is.........the safety never came off, the hammer never moved, the slide never cycled........the only reason it fired was because of the firing pin block safety not being strong enough to overcome the magnetic force against it. Any gun would have had the same issue.
 

ODA 226

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I'm going for an MRI of my right shoulder next week. I'll make sure I leave my Springfield with my wife! LMAO!
 

deepdiver

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compmanio365 wrote:
...the only reason it fired was because of the firing pin block safety not being strong enough to overcome the magnetic force against it. Any gun would have had the same issue.
If the posted analysis is correct rather than Doug's hypothesis, it was not only the firing pin block moving, but also inertial forces from the gun flying out of his hand and into the MRI, with the muzzle pointing in the direction of travel thereby giving the firing pin the inertia required to strike the primer. If it's momentum had been sideways and back rather than forward I would think it would not have happened. Truly a freak occurrence.

"Any gun" would not have this issue in such a freak occurrence. XD and Glock strikers are physically held in place against the striker spring force by the sear and the sear in turn is physically connected to the trigger via the trigger bar making them near impossible to set off without pulling the trigger even if dropped from several stories. I'm guessing this would be true at least to some extent for all striker fired weapons as that is the means of giving the striker the inertia otherwise given by the hammer fall. However, I am not familiar with other striker fired handgun internals to verify.
 

Aegis

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At an average price of 6-10 million Dollars ( U.S.) for MRI machinery, its safe to say that the officer in question was VERY fortunate he got away with minimal cosmetic damage to the machine....a bit of Bondo &Krylon should fix this little boo-boo.

On A More serious note.....it is very fortunate indeed that the only damage was to the MRI and not another person.
 

Doug Huffman

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Good point.

I looked at http://www.ajronline.org/cgi/content/full/178/5/1092/FIG2 to see if the magazine was still with the gun.

In re-reading the URL it appears that the field was on when the Pt and gun entered the suite and that the gun was influenced by the field only when the Pt placed it on a cabinet a meter away.

I'm a bit surprised to read of the expense of maintaining a 1.5T field without a Pt.

I'm a bit surprised that the Pt didn't notice the field's effect while the gun was still in his hand.

I wonder if there was any follow up?
 
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