January 1, 2011

In our last post, we were talking about stereotactic radiosurgery (SRS) devices that have been the source of radiation overdoses and serious brain injuries. Doctors in Portland were among the thousands who received warnings about the retro-fitted linear accelerators after the full extent of the injuries became known.

Pinpoint accuracy is the key to SRS. A standard linear accelerator produces too large of a beam for the kind of work that needs to be done. To narrow the beam to the necessary size, one manufacturer adapted a linear accelerator by attaching a cone to the opening where the beam came out. With this model, the retrofit had to focus a square beam through a round outlet. If the cone is smaller than the square beam, radiation leaks at the corners, damaging healthy tissue.

Only after three patients were overdosed did one Midwestern hospital discover that the beam was four times too large. The investigation showed that the operators could not see the incorrect settings because the mounting apparatus for the cone was in the way; further, the mount blocked a light field that could have shown the operators where the beam would hit.

The medical team maintained that they had followed the manufacturer’s instructions. According to the New York Times, the retro-fitted device includes a “complicated matrix of computer systems and communication flaws” that greatly increased the likelihood of an accident like this.

The question, then, is how such a flawed device made it to market. One of the patients injured at the Midwestern hospital went in for treatment of a non-life-threatening condition; a year later, she “was like a vegetable,” according to her husband. The stakes are high, because brain injuries can be catastrophic. Why haven’t regulators acted?

Continued in our next post.

Source: New York Times “A Pinpoint Beam Strays Invisibly, Harming Instead of Healing” 12/29/10

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