Philips recalls 340 MRI machines because they may explode in an emergency

[jt2190]

The Food and Drug Administration’s web page about the recall is clearly written:

(edit: actually not a recall but a requirement that the machines are not used until they’re serviced)

https://www.fda.gov/medical-devices/medical-device-recalls/p...

[Jabbles]

There has been one reported event of an explosion in 22 years of use. There have been no reports of injury or death.

I wonder what the total negative health consequences of not being able to use all those MRI machines until they are serviced will be.

[akira2501]

That's absolutely a recall. An FDA recall means the product is in violation of the law. Those violations must be corrected or the device must be destroyed, and if not, then the FDA has the right to seize it.

The recall strategy in this case is not to ship it back to the manufacturer, but to have the manufacturer come out and service the device until it is again compliant with the law.

[trebligdivad]

I dont understand what the fault is - quenching is bad but happens. Blocking the quench path sounds bad - is it saying that something is causing it to be blocked or is the machine supposed to do something else if hte quench path is blocked (what can it do??)

[EA-3167]

The rapid conversion from liquid or solid to gas, and the means to (briefly) contain that... is a bomb. The reason you don't block the emergency relief is that you turn a quench from an emergency involving asphyxiation, to something resembling a detonation.

[crest]

The Helium used for cooling expands a lot going from liquid to gas during a quench (iirc by a factor of ~1800). The pressure built-up from the phase change has to be relieved *quickly* before the machine turns into a crude pipe bomb. Oh and you can't get enough Oxygen from the air if most of it has been replaced with leaked Helium.

[cperciva]

Note: MRIs are incredibly safe. Your risk of dying due to an MRI machine exploding is significantly less than your risk of dying due to falling while climbing into the machine.

[fabian2k]

You should respect the magnet though. Those warnings aren't there without reason, getting between an MRI or NMR and a magnetic piece of metal is a bad idea

[figmert]

~~I don't know why this is relevant, and quite frankly I find comment odd. Just because y is safer than z, does not mean we should ignore reasons why z isn't safe.~~

See OP's response for why this is crossed out (assuming HN supports it).

[akira2501]

Liquid helium has a 745:1 expansion ratio when converting into a gas. So, that's not a fun problem to have.

[fbdab103]

A helium leak was responsible for taking down the large hadron collider for this same reason. Sudden volume expansion with nowhere to go.

CERN retrospective on the event: https://home.cern/news/news/accelerators/lhc-leak-repair-sho...

[dukeofdoom]

At what point are less safe but cheaper machines worth it. Hospitals ration MRI machine access through out the world. Even in Canada, you have to wait on a list to get access.

"Canada could expect to wait a median of 5.4 weeks for a CT scan and 10.6 weeks for an MRI scan"

[LegitShady]

thats because Canada has less than 20% the MRI machines proportionally to population as Japan, and 25% of the MRI machines as the US. We're down near the Czech Republic and Turkey.

From 2019:

https://www.statista.com/statistics/282401/density-of-magnet...

I didn't look very long so maybe there's more recent numbers available.

[lnsru]

Is it not the case, that wait time goes to zero if you pay in cash immediately?

[jokoon]

I worked in x ray imaging software in a company that assembled them.

Risk assessment and traceability are not fun, but it's interesting to see how to make safe things.

I wish general software had similar constraints or designs, or at least insurance companies would lobby the government to force software companies to proof read their code.

I don't want rust everywhere, but it should still be possible too approach what rust is doing by other means.

[serial_dev]

Toxic teams and lazy developers will also find way to produce crappy software with Rust.

The Rust developers of today might produce better software, because they are the early adopters who care about performance, safety and correctness, but I believe (assuming Rust becomes mainstream) if you give regular developers Rust to code in, they will produce the same quality as they do with Java, Javascript, or C.

The environment and the individuals are significantly more important than the programming language they use.

[refulgentis]

Where would i go to learn the fine details of how things like risk assessment and traceability work in practice?

[BobaFloutist]

Well that's definitely not what they're supposed to do.

[pstuart]

It's a pity that the helium is vented out, considering its increasing rarity.

I'm guessing that capture and reuse probably would add way too much to the price of the machine.

[fabian2k]

This is about quenching, which happens in emergencies or failure. During regular use helium is recycled in similar systems often today. But it's simply not feasible to do that when all the liquid helium in there evaporates at once

[ars]

This only happens in an emergency, not during normal operation.

Pretty much the only time you would do it when a person is stuck in the machine by some piece of metal that is attracted to the magnet. You hit the quench button which vents all the helium, but more importantly also halts the magnet (all the energy released from halting the magnet goes into boiling the helium), and then you can release the person.

You don't do this for any other purpose, for example if some metal cart is stuck in the machine, but no one is at risk, you use a slower method to shut down the magnet (i.e. drain the energy) that doesn't vent the Helium.

[Metacelsus]

It can be recovered, see for example: https://news.ucsc.edu/2019/12/helium-recovery.html

[namibj]

The issue in that respect is that they flood the coils in a helium bath, instead of utilizing additional structures like channels/nozzles to provide the same rate of freshly cooled helium to the heat sources as the bath does, but with far less helium required in the system.

[cperciva]

If you suddenly have thousands of L of He gas on your hands, venting is better than exploding.

[hinkley]

“I don’t wanna explode.”

[lnxg33k1]

Its unbelievable the decline of philips, i used to buy their stuff out of trust, but given their story with ventilators, this one, and other personal ones with razors, waterfloss and toothbrushes, I wouldn’t touch anything from them with a ten foot pole

[terom]

> There has been one reported event of an explosion in 22 years of use. There have been no reports of injury or death.

[dr_kiszonka]

I am puzzled by it. It is a pretty conservative company that used to put a lot of focus on safety. What happened?