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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?"
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
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
'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."'
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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?
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.