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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?"
As long as people are involved in some way, no.
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.
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.
Palm trees and 8
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!)
----- The internet has given everyone the ability to have their voice heard equally as loud.. even if they shouldn't be
Will we ever learn enough to make these errors truly uncommittable?"
No.
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.
"Before God we are all equally wise - and equally foolish"
Albert Einstein
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.
"I am the king of the Romans, and am superior to rules of grammar!"
-Sigismund, Holy Roman Emperor (1368-1437)
For comparison remember more people are killed by vending machines and by falling off the roof putting up the christmas lights.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
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.
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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.
Truth is like the sun. You can shut it out for a time, but it ain't goin' away. - Elvis Presley (source: imdb.com)
Life is brutal, but that doesn't mean we should give up on trying to make it less so. Asking whether CT scanners can be redesigned to make this not happen, and whether it's worthwhile to do so, is very valid.
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.
Give a man a fire and he'll be warm for a day. But light a man on fire and he'll be warm for the rest of his life.
For patients undergoing scans or treatments involving radiation, why not verify exposure with a 25 cent dosimeter? You'd catch problems right away.
Comment removed based on user account deletion
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...
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.)
No kidding!!! What do you say at this point?
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.
Monstar L
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...
I'm trying to teach myself to set people on fire with my mind... Is it hot in here?
So, if this CT error bothers you, do you really think the onslaught of IT technology being thrust at hospitals is going to make things in health care any better? The Obama Administration is creating a feeding frenzy among the IT companies to rush in and collect their piece of the pie. To do this, they are creating electronic health records and connecting medical devices to regular IT networks. Who is testing that stuff? Mind you, I don't think Obama's move is necessarily bad, just the blind faith driving it that more technology is always a good thing. Even NASA finally figured out that their "Faster, Cheaper, Better" programs didn't mean "Faster + Cheaper = Better."
Granted, the Silicon Valley/Redmond group have created some remarkable technology, but should we take for granted they are doing all the right things in areas they've never worked in before? It seems to me we all put way too much faith in our technology... as illustrated by the comments that this CT should correct for all potential errors a human might make. If this were really the case, why is there still so much crappy hardware and software out there?
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.
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.
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????
http://www.geoffreylandis.com
Not true because the proposed button/switch would only need to be used exceptionally.
There are enough possibilities to make it fool proof.
For example, there could be two push buttons, one is to reset the scanner to normal levels and one to enable high levels. An electronic timer automatically resets it back the lower level after an hour, or when the scan session ends. To prevent taping down, the buttons must be released before it can be pushed again, this is easy to detect using a few flipflops and AND/XOR ports.
Yes, because we all know that car accidents only kill stupid people...
I don't think the laws of physics cares how high your IQ is when you get t-boned by a drunk driver at an intersection.
And as I posted earlier, customers have been caught with weights to hold down buttons.
In this particular case though, that particular dosage may have been appropriate to some uses, but not others. A "maximum allowed dose" can be in effect and still make a patient sick!
For some machines these doses are controlled mechanically; moving heavy lead and steel plates around, irises, etc. Hardwiring a maximum dosage in this case involves the interaction between many components.
...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.
Don't you wish your girlfriend was a geek like me?
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.
One thing that struck me from that story (and is appropriate for Slashdot) is from a meeting between Therac-25 users and the manufacturer, after several deaths had occurred from two separate software bugs. The users asked if the manufacturer would provide the source code for the machine's software, so they could look at it themselves. The manufacturer said no.
Given that lives are at stake, this seems like an obvious thing for the FDA to do - demand that all medical devices be open-source. Even if operators of the devices don't actually trawl through the code themselves (at least, until an accident has occurred), the knowledge that they *might* should motivate manufacturers to be a bit less sloppy.
"Even an idiot who did not RTFM should not be able to cause harm with the machine."
But was this above that limit?
Different scans REQUIRE different amounts of radiation.
Nothing can be fool proof. I would bet that there is a limiter but this level could be below that limiter.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
The watchdog timer on the radiation module detects lack of input and shuts it down?
Ironically, earlier models of the Therac device *did* have hardware interlocks. These earlier models shared the same software defects as the Therac-25, but hardware interlocks prevented the overdose scenario.
I haven't RTFA, and I don't even pretend to assume that I could do things better (or even fully grasp the problem). That said, the struggle for efficiency and programmers' tendency to seek out a software solution to any problem seem to be at odds with the multiple levels of redundancy, checks, and balances that are absolutely required for medical technology.
I would loathe being a software developer in the medical industry. It's a noble thing, but the knowledge that my mistakes could potentially *kill* other people would make me sick.
Well, the Therac-20 "worked fine" in the sense that the mechanical limit on the device prevented the software from delivering lethal doses. It doesn't mean that the Therac-20 was a "good" machine in any sense of the word.
We all know what to do, but we don't know how to get re-elected once we have done it