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

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.

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.

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.