Radiotherapy Mistakes: Trusting Too Much In Computer Technology?

Worrisome Errors in System Designs and Operator Interactions With Radiotherapy Equipment: Will AAMI Standard HE75 Make a Difference?

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Radiotherapy Mistakes: Trusting Too Much In Computer Technology?

The New York Times yesterday published a very long and disturbing piece on the painful, lingering death of cancer patient Scott Jerome-Parks by radiation overdose. An undetected computer error "directed a linear accelerator to blast his brain stem and neck with errant beams of radiation. Not once, but on three consecutive days," the Times reported.

There is animation of the sequence of events that led to Scott Jerome-Parks radiation overdose here.

The Times story describes a number of incidents where operator error as well as hardware and software problems have resulted in patients receiving incorrect radiotherapy doses that have resulted in patient injuries and sometimes death.

Times reporters looked at 621 cases of radiotherapy mistakes reported to the State of New York between January 2001 and January 2009. The State of New York, the Times says, "is a leader in monitoring radiotherapy and collecting data about errors," which why it was chosen for the article.

The Times' analysis showed that of the 621 cases reported, 46% of the time the radiation missed all or part of the intended target, 41% of the time a wrong dose was given, 8% of the time a wrong patient received the radiation, and 5% were listed as other.

State records showed that 1,264 causes were given for the 621 radiotherapy mistakes.  The largest number related to having a flawed quality assurance plan (listed 352 times), data entry or calculation errors by personnel (252 times), misidentification of patient or treatment location (174 times), blocks, wedges or collimators misused (133 times), patient's physical set up wrong (96 times), treatment plan flawed (77 times), hardware malfunction (60 times), inadequate staffing or training (52 times), computer software or digital information transfer malfunction (24 times), override of computer data by personnel (19 times), and various other reasons for the rest.

From the stats and from the story itself, not following proper safety procedures and operator error were the most significant causes of the reported mistakes, but the story also makes clear that the computer system design of radiotherapy equipment still leaves a lot to be desired, even 25 years after the Therac-25 incidents, especially in regard to reducing operator error.

The Times story states that, "Without a doubt, radiation saves countless lives, and serious accidents are rare," but also that "while this new technology allows doctors to more accurately attack tumors and reduce certain mistakes, its complexity has created new avenues for error."

Dr. Howard I. Amols, chief of clinical physics at Memorial Sloan-Kettering Cancer Center in New York, told the Times that hospitals are "often too trusting of the new computer systems and software, relying on them as if they had been tested over time, when in fact they have not."

As diagnostic radiotherapy continues to increase (patients receive seven-fold more radiation today than they did in 1980, the Times states), more mistakes may be a possibility.

Last October, for instance, Cedars-Sinai Medical Center in Los Angeles, California  reported that more than 200 patients were inappropriately exposed to high doses of radiation from CT brain scans used to diagnose strokes. Another 50 were identified once hospital records were reviewed.

Cedars-Sinai blamed the incorrect doses on a "misunderstanding about an embedded default setting applied by the machine."

GE, the manufacturer of the machine used, said however that "there were no malfunctions or defects in any of the GE Healthcare equipment involved."

The problems at Cedars-Sinai led to the US Food and Drug Administration (FDA) issuing an alert to US hospitals to review their safety procedures for CT scans.

Shortly after, three other hospitals, two in the Los Angeles areas (Glendale Adventist Medical Center and Providence St. Joseph Medical Center) as well as one in Alabama (Huntsville Hospital) were reported to have radiation overdose incidents of their own. The FDA updated its alert as a result.

By accident, I stumbled across this recent article on the new Association for the Advancement of Medical Instrumentation human factors standard AAMI HE 75, "Human Factors Engineering - Design of Medical Devices." At some 600 pages, it appears at a quick glance to be pretty comprehensive.

For those of you in the medical device business, how much do you think this new standard will help avoid the problems listed in the New York Times and other articles?

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