Marci Farber sought radiosurgery to treat a pain from a nerve deep in her head. Today, she's "in a nursing home, nearly comatose, unable to speak, eat or walk." What happened? The radiation hit places it wasn't supposed to.
Her story, reported in today's NYT, is far from an isolated incident, and it speaks to the dangers faced when hospitals struggle to keep their technology updated for the most cutting edge procedures.
Stereotactic radiosurgery (SRS) is a fast-growing radiation therapy in which tumors in the brain or spine are blasted with an intensely concentrated beam of radiation. For such treatments, some hospitals have invested in $US3 million dollar device called the Gamma Knife, designed specifically for SRS. But at other hospitals where the patient demand does not justify the Gamma Knife's cost, linear accelerators, machines used for standard radiation therapy, have been retrofitted for SRS treatments, in many cases being combined with parts from various different companies. When used correctly, these modified machines can administer SRS without issue—it's an attractive alternative to more invasive surgeries because it can be performed as an outpatient procedure and in some cases can be completed in just one day—but converting linear accelerators into SRS-ready machines is a process with potential for extremely harmful error:
Linear accelerators can be adapted to perform stereotactic radiosurgery in two ways: with small computer-controlled metal leaves that shape the beam, or with a cone attached to the machine's opening through which radiation is delivered. That opening is made smaller or larger by moving four heavy metal "jaws" that shape the beam into a square. When a cone attachment is used, the square beam must fit entirely within the circumference of the cone. If the square is slightly larger than the cone, radiation will leak out through the four corners of the jaws and irradiate healthy tissue. In the Evanston accidents, records show, the beam was four times too large.
The Evanston accidents refer to Marci Farber and and two other patients who were overdosed with radiation by the same faulty machine. And they're far from the only ones: Earlier this year, CoxHealth, a hospital in Springfield, MO, announced that it had overradiated 76 patients during SRS treatments, due to equipment that had been set up incorrectly. The NYT outlines a "complicated matrix of computer systems and communication flaws"—in both the companies that make the equipment and the hospitals that use it—responsible for the incorrectly calibrated machines.
While these incidents are far from the norm, the problem is exacerbated by a general lack of regulatory oversight with regard to modified linear accelerators. Where the Gamma Knife, which uses its own radioactive isotope, is regulated strictly by the Nuclear Regulatory Commission, linear accelerators are overseen by the FDA, which approved the modified machines with little scrutiny because they were deemed extensions of existing technology. Furthermore, the FDA doesn't require hospitals to submit linear accelerator accident reports to a central database, which has made it difficult to connect these various accidents and pinpoint their causes.