CT Scan "Reset Error" Gives 206 Patients Radiation Overdose

jeffb (2.718) writes "As the LA Times reports, 206 patients receiving CT scans at Cedar Sinai hospital received up to eight times the X-ray exposure doctors intended. (The FDA alert gives details about the doses involved.) A misunderstanding over an 'embedded default setting' appears to have led to the error, which occurred when the hospital 'began using a new protocol for a specialized type of scan used to diagnose strokes. Doctors believed it would provide them more useful data to analyze disruptions in the flow of blood to brain tissue.' Human-computer interaction classes from the late 1980s onward have pounded home the lesson of the Therac-25, the usability issues of which led to multiple deaths. Will we ever learn enough to make these errors truly uncommittable?"

Comments

Will errors ever go away?

[s73v3r]

As long as people are involved in some way, no.

Re:Will errors ever go away?

[courteaudotbiz]

Mmmmm, anyway, people are always involved if you have a machine. The machine didn't build itself!

Re:Will errors ever go away?

[argent]

The machine didn't build itself!

SPEAK FOR YOURSELF, MEATSACK!

Re:Will errors ever go away?

[Arthur Grumbine]

The machine didn't build itself!

SPEAK FOR YOURSELF, MEATSACK!

Oh, yeah?! Well who built your first model, you bucket o' bolts! And don't give me that FSM nonsense. Everyone knows that the Fantastical Spawning Machine was truly the work of humans, inspired by the intelligently designed schematics given to us by the noodley appendage of the true FSM.

Re:Will errors ever go away?

[FatdogHaiku]

SPEAK FOR YOURSELF, MEATSACK!

Scanning with high intensity radiation reveals he is in fact about 60 percent water, 16 percent protein, 15 percent fat, and about 3 percent nitrogen... So, more of a stringy, greasy, slightly gassy water bag really.

Sorry about the high levels of radiation used to obtain the data, your armpits should stop smoking any minute now.

Re:Will errors ever go away?

[Itninja]

Don't be such a dolt. The machine is the product of evolution. Millions of years ago a bolt of lightning hit some random alloys and a simple logic circuit was born. Fast-forward to now, and *poof* CT scanner! It just make sense.

Not the engineers fault

[PhasmatisApparatus]

Requiring that doctors RTFM is the first step.

Re:Not the engineers fault

[betterunixthanunix]

The machine's software should not be capable of triggering the release of that much radiation; any change in the radiation levels should require some kind of hardware interaction. Even an idiot who did not RTFM should not be able to cause harm with the machine.

Re:Not the engineers fault

[smitty777]

Couldn't disagree more. Unfortunately, enforcing training and reading manuals would probably have little effect. In my 10+ years doing usability for missile systems, you have to build in the mechanisms to keep the users from doing bad things. Even if you force the user to read the *entire manual* before each use, people still have bad days, hangovers, fights with significant others. It has to be designed in.

Re:Not the engineers fault

[vertinox]

The machine's software should not be capable of triggering the release of that much radiation; any change in the radiation levels should require some kind of hardware interaction. Even an idiot who did not RTFM should not be able to cause harm with the machine.

I'm not sure what you mean by this? Most hardware is software these days.

Or are you talking about having a red button with a safety lock on it that has to be pushed in order to work?

Either way, people still bypass hardware solutions.

Re:Not the engineers fault

[snowraver1]

Hardware interaction... Like maybe "[...]resetting the machine to override the pre-programmed instructions that came with the scanner when it was installed."?

I'm willing to bet that the person that modified the machine has read, at least, the relevant parts of the manual.

Re:Not the engineers fault

[Serenissima]

I think he means it should be hardwired into the unit to NEVER EVER exceed a certain level of X-Ray radiation. That should be the default. If there's some medical reason why the dosage needs to increase, you should have to turn it UP to that dosage and then the machine should reset itself to the default. There should NEVER be a problem of the machine defaulting to an extremely high level of radiation requiring personnel to turn it down. It should always start out low in case some dumbass technician runs the machine without making any changes.

Re:Not the engineers fault

[Sockatume]

Don't even hard-wire it. Engineer it so that operating in the high-dose regime requires physical intervention, a "Kill Handle" with a lock and key. The machine should be physically incapable of generating an above-standard dose when the "Kill Handle" is not being held. Limit the power, or something. (The aformentioned Therac incident happened, in part, because such a hardware interlock did not exist.)

Re:Not the engineers fault

[Greyfox]

My machine would irradiate the operators by default and would require that a obscure button sequence be pushed in order to irradiate the patient instead. That way the idiot who didn't RTFM would end up dying of radiation poisoning, not the patient. Eventually the survivors who DID RTFM would breed and pass on their proclivity to RTFM. Really it's for the good of the entire human race, if you think about it...

Re:Not the engineers fault

[BigDukeSix]

It's not quite that simple. The CT scanner is set up with a distinct scanning protocol for whatever part of the body you're imaging. If you're trying to get a detailed image of the bones of the pelvis you have to use more power than if you're imaging the lungs. The scan is further individualized by patient size. Given that infants and very large people are imaged on the same scanner, the software has to vary radiation dose over a reasonably wide range, and it's a different setting for every scan.

Re:Not the engineers fault

[Geoffrey.landis]

The machine's software should not be capable of triggering the release of that much radiation

That sentence, essentially, just said "The machine did something bad. It should have been designed so it isn't allowed to do that."

That's what qualifies as "insightful" these days????

Re:Not the engineers fault

[RobertLTux]

I see you are about to fry this patient like an egg (doseage set for multiples of normal protocol)
would you like me to

1 reset the machine to standard defaults
2 book you a flight to africa
3 call your lawyer now
4 forge the documents to show %person% did the treatment

or
You Are about to kill this patient [cancel] or [allow]

Re:Not the engineers fault

[uncqual]

Just make the button detect authorized fingerprints only and require a heartbeat in the finger and also scan the operator's retina and alter lighting to make sure that the iris responds "correctly" to random changes in light level.

Bet you can't circumvent that with just duct tape. Now, with an Arduino, some peripheral hardware and a few spare evenings....

Re:Not the engineers fault

[lysergic.acid]

Thank god you're not responsible for the design of complex, life-critical systems, like those commonly found on passenger jets, in nuclear power plants, in high-speed rail systems, etc. All of those systems incorporate fail-safe measures so that if something were to go wrong (like an operator losing control) the system would fallback on a safe state.

Sure, in an ideal world, every operator of a life-critical system would have total understanding of that system, know the value of every system setting at all times, never forget, never be tired, and have an IQ of 200. In the real world, operators are often overworked, susceptible to distractions, minimally qualified, and sometimes under-trained or even improperly trained. Even the most experienced and well-trained veteran airline pilots can lose focus and make deadly mistakes (which is why Cockpit Resource Management has been a major area of research in aviation psychology). You can base your system design on ideal conditions, or you can base it off of real-world conditions; either way, it's going to be operating in the later.

You also seem to be missing the main purpose of mechanization and automation, which is to simplify a task or make it easier to perform. When you buy a cappuccino machine, you don't want to understand the details of how it operates or be asked for input every step of the process to make a cup of coffee. Eliminating/minimizing the human factor in a particular process is another major advantage of automation. It provides more consistent results and helps to minimize human error. All of this helps to reduce the learning curve and skill level required to perform a task, which confers economic benefits. However, not every well-designed system can necessarily be operated by unskilled personnel—nor would you want a high school drop out to be operating most life-critical systems. Nonetheless, you still want mechanization/automation to simplify the task in these cases. That's because some tasks are so inherently complex and mentally demanding that, without automation, it simply can't be performed.

Flying a passenger jet is a perfect example of this. Even with all the sophisticated automation (including autopilot) on a modern airliner, it still takes a full cockpit crew (not to mention support personnel on the ground) to safely fly & land the plane. With all of the complex duties that airline pilots need to perform simultaneously, they don't have the time to monitor the status of every system component or manually adjust every actuator on the plane to control its flight surfaces. It may take 50 different mechanical actions to retract the landing gear on a plane, but why clutter the cockpit interface with 50 items when a single switch or button will do? Likewise, doctors and nurses are already required to undergo extensive medical training; they don't need to have to learn how to mechanically calibrate a CO2 laser or calculate the spectrum of an X-ray machine based on the anode material of its emitter and the voltage passed through it. Medical personnel should mainly be trained in medicine and only need to learn how to operate a particular medical device, not how to troubleshoot it or read its blueprints.

A simple and streamlined interface is much less distracting and more intuitive than a field of buttons and dials for a thousand different minute settings and system readings. Even with the utmost simplification, most industrial machinery and complex systems are still overwhelmingly difficult to operate by an untrained person. It's never just a single "magic button" for the operator to press. A nuclear power plant might take hundreds of different readings from multiple sensors and summarize it with a single status message or indicator light on a controller's console, but that message/light would likely be sitting next to a dozen other status indicators that each take hundreds of other readings. And although a complex process like lowering the reactor temperature might be simplified down to a single "magic button," the c

Default setting...

[courteaudotbiz]

The default setting for an equipment that can be lethal should be "Emit zero radiation". Then for each exposure, set the level of radiation you intend to use. This way, you ALWAYS KNOW the level of radiation the equipment will emit.

Better investigate "Hey, we got no picture" than "Hey, we got pictures, but everyone dies after that..."

Didn't RTFA.

Re:Default setting...

[eln]

That's really not fair...you have no idea that people would die from that radiation. It's at least equally likely they would develop super powers, join up with others who have received similar doses of radiation, and form a crime fighting team of mutants.

All I'm saying here is we shouldn't just dismiss this as a bad thing until we've fully explored the legislative and societal implications a team of crime-fighting mutants with superpowers would have.

HULK MAD!

[BumbaCLot]

Even under normal circumstances, the procedure requires more radiation than most other types of CT scans, said David Brenner, director of radiological research at Columbia University Medical Center in New York.

Anyone else read this as David Banner?

Re:HULK MAD!

[frito_x]

Hate this "immediately moderate when you select an option" feature. meant to mod funny... slip of the mouse goes to overrated... there should be a go/ok button next to the list imho.

wasted 3 mod points... oh well...
     

Maybe testing it afterwards?

[uncledrax]

Maybe next time they will test the damn thing before subjecting patients to it? It's a built in part of my job that I test/confirm a change after I make a change.. because often there's a likely hood of something unexpected or improperly explained that can cause an issue.

How hard would it have been to stick a dosimeter in the machine after the change and run it though a test?
(I realize that just a basic dosimeter might not be a sufficient measure.. but it would have been good to get a before/after.. and something like a 8-fold increase would have been easily detectable!)

Re:Maybe testing it afterwards?

[RDW]

'How hard would it have been to stick a dosimeter in the machine after the change and run it though a test'

Supposedly the actual dose would have been displayed on the machine's screen (I wonder how prominently?):

http://www.latimes.com/news/local/la-me-cedars-sinai14-2009oct14,0,5065886.story

'"It's in your face on the screen," said Dr. Donald Rucker, chief medical officer for Siemens, a manufacturer of CT scanners.'

'CT technicians are trained to monitor dose levels, and some hospitals conduct checks before every scan..."There are other places where the techs might be operating more as button-pushers," said Dr. Geoffrey Rubin, a professor of radiology at Stanford University. "The user becomes a little blind to these numbers."'

Medical Staff were a big part of the problem

[CheddarHead]

Along with the usability issues with the design of the Therac-25 it's obvious that the attitude of the medical staff contributed greatly to the problem. Patients complained of being burned, but their complaints were essentially ignored. Meanwhile, they were sent back for multiple treatments. Overwhelming evidence of radiation burns was ignored or given only cursory investigation because medical personal or manufacturer reps claimed that it was impossible for the Therac-25 to be responsible for the burns.

The errorless machine...

[TemporalBeing]

Will we ever learn enough to make these errors truly uncommittable?"

There is and never will be such a thing as a machine without the possibility for error. And you'll never get around the old adage/rule - If it can happen, it will. How often it occurs it the key; and while we should always aim to make an error-less machine, it is an impossibility and we can only achieve it by make the occurrence of such errors as few and far between as possible.

After all, an error-prone human must be involved to make the machine; even if that machine made another machine a human was still involved at some point to make the original. Thus there will always be the possibility for errors. Even if, as demonstrated by the Matrix, iRobot, and many others, the machines make that error on purpose to save humanity - it is still an error.

Feedback?

[TopSpin]

Will we ever learn enough to make these errors truly uncommittable?"

No. As long as correctness can't be proven and operators are permitted to create unanalyzed conditions by altering protocols there will always be risk. There are probably other mis-configured CT scanners out there in use right now that have been overdosing patients for years.

CT scans use X-rays; an easily detected frequency of light. Why not require that scanners incorporate an independent detector that measures the amount X-ray energy? If that is possible then create an interlock that can shut down the emitter when the net energy gets out of bounds and require that any such incident be NRC reportable. If the detector excluded from alteration by the operators then software bugs, misunderstandings, etc. can be detected even years after the last engineer had contact with the system, either before harm is done or at least before hundreds of patients are literally burned.

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[account_deleted]

Comment removed based on user account deletion

Re:It's About Automation

[antifoidulus]

The advantages of simplified training are not just beneficial on an economic scale. While its unfortunate that this error killed people, think of how many more people would die if complex training was required to use these types of machines. Ultimately, it would lead to fewer operators and thus less access to the machine, which ostensibly helps save lives.

Re:Don't be such a wuss

[MRe_nl]

In 1895, Thomas Edison investigated materials' ability to fluoresce when exposed to X-rays, and found that calcium tungstate was the most effective substance. Around March 1896, the fluoroscope he developed became the standard for medical X-ray examinations. Nevertheless, Edison dropped X-ray research around 1903 after the death of Clarence Madison Dally, one of his glassblowers. Dally had a habit of testing X-ray tubes on his hands, and acquired a cancer in them so tenacious that both arms were amputated in a futile attempt to save his life.

Re:It's About Automation

[sunderland56]

I don't think being trained to fully understand the automobile will decrease the number of automobile related deaths.

Being trained to fully understand the laws of physics would certainly decrease automobile accidents.

Re:It's About Automation

[digitig]

This particular error is the kind that occurs when you simplify complex procedures in the interest of widespread use. It is the fault of specialization, which we typically embrace because it allows us to leverage human labor into increasingly complex areas of inquiry. It's more than just "human oversight" or "machine failure," it's the kind of problem that typically arises when people are trained to use machines without being trained to fully understand those machines.

A certain segment of society--that's mostly us geeks--strives against this tendency; we become technicians in various fields. But most people, including medical people, get trained by vendors to use a particular piece of software or hardware without reference to its underlying principles or inner workings. This is normal and usually beneficial for various reasons an economist could doubtless relate.

But one of the things that we geeks should be doing is looking at equipment like this in its overall system context, which includes the operator and which includes the training the operator has received. That's mandatory in the Aviation industry pretty much worldwide (my field); I don't know what the situation is for medical equipment in the USA. No, we will never make such mistakes "uncommittable" -- perfect safety is a myth. But we should be considering possible failure modes, and the likelihood and consequences of those failure modes, to ensure that the risk is tolerable.

Re:Pretty narrow margin

[DragonWriter]

It can actually become an issue if someone needs radiation therapy ('chemo')

"chemo" refers to chemotherapy, where the patient is poisoned in the hopes that the poison will kill the cancer faster than it kills the patient. It is a different form of therapy than radiation therapy, in which the patient is subjected to intense doses of radiation in the hopes that the radiation will kill the cancer faster than it kills the patient. Often, people with cancer will receive both, one after the other, but they aren't the same thing.

Some quantitative perspective

[goodmanj]

Typical normal CT scan dose: 1-2 rem
Faulty CT scan overdose: 8-16 rem
1950s shoe-salesman's fluoroscope: 10 rem
Typical normal Therac-25 dose: 200 rem
Malfunctioning Therac-25 dose: 15-20,000 rem

Come on, seriously people. Yes, this is a mistake that needs to be fixed, but millions of kids in the '50s got their feet nuked with this much radiation and lived to become healthy normal adults with normal feet.

The Therac-25 cooked straight through people, leaving a hole of rotting meat behind. This is not even remotely in the same league.

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/R/Radiation.html
http://chestjournal.chestpubs.org/content/107/1/113.full.pdf
http://www.ccnr.org/fatal_dose.html
http://www.orau.org/ptp/collection/shoefittingfluor/shoe.htm

Re:It's About Automation

[Ironica]

...But in that particular accident, the drunk is less likely to suffer severe or fatal injuries. The relaxant effect of alcohol makes their body more resilient to sudden shocks. Also, they're usually having a head-on collision, while they may be striking the other vehicle from the side; as head-on collisions are by far the most common, most of a car's safety features are geared toward mitigating them.

Re:It's About Automation

[Lost Engineer]

The person who reacts correctly to a slide is not doing so because he understands physics in general but because he has driving specific training. There's really no time to do math in that situation.

Re:It's About Automation

[Kratisto]

Speak for yourself. I mounted a pad of engineering paper to my dash for just such an occasion. Just this afternoon I was drifting to the left due to rain slick roads, and once I had done the necessary calculations, I realized I ought to depress the throttle 16 mm and turn the steering wheel 68.5 degrees in the +x direction in order to regain control.

Re:It's About Automation

[dgatwood]

Was that before or after your car hit the bottom of the ravine?

Re:It's About Automation

[Tired and Emotional]

I don't know. I never have really understood Statistical Mechanics and I have probably not already died in a car accident.

Re:It's About Automation

[Ironica]

Woops, silly me, repeating what I learned in upper-division Transportation Engineering lecture from professors with decades of experience in the field of road design. Guess I should have checked Wikipedia first, because it never lies!

Got a cite for your critique?

It's true that the majority of people who die in alcohol-related crashes have a BAC of .08 or higher (67% according to this site). However, lower down, we see that 37% of single-car crashes involve a BAC of .08 or higher, which is higher than the 22% average rate. Since my point was about the comparative risks to the drunk driver and the sober driver in an accident, single-car crashes are irrelevant. That takes out 67% of the drunk driving crashes overall, and similarly lowers the fatality numbers considerably.