“Arguably, the physicist or radiation therapist should have noticed that there was a mismatch,” Dr. Amols said, “and arguably there should be stricter laws regulating the ‘mixing and matching’ of complex medical equipment from different manufacturers. But at present there’s no legal requirement for different companies to make equipment integration transparent to the end user — i.e., the hospitals.”
After the accidents at Evanston, Brainlab and Varian this year released a software fix that will restrict the jaw size, so similar accidents will not occur, said David Brett, a Brainlab official. So far, 75 percent of the affected machines have incorporated the fix, the company said.
Dozens Are Overradiated
While Evanston and its suppliers were dealing with the fallout of the overdose cases there, a different problem involving the retrofitted linear accelerators had been unfolding at CoxHealth, a hospital in Springfield, Mo.
Earlier this year, CoxHealth announced that it had overradiated 76 patients, most of whom had brain cancer, during SRS treatments. The overdoses had continued for five years because the hospital did not realize that its radiation therapy equipment had been set up incorrectly.
The hospital’s medical physicist, who was apparently accustomed to calibrating larger radiation beams, did not realize that smaller beams needed to be handled differently, radiation experts say.
A hospital spokesman said the physicist used the wrong calibration tool to set up the machine, causing the overdoses.
“They were supposed to have switched over to a smaller detector,” said Dr. Brad Bradshaw, a lawyer, who represents many of the overdosed patients. “The larger detector gave them a false reading.”
Terri Anderson, 54, was overradiated at Cox last year while undergoing SRS treatment for a benign tumor. After her treatments, she began experiencing facial spasms. “I started having 12 to 14 of those a day,” Ms. Anderson said. She says she also developed balance and memory problems.
Dr. Bradshaw, who represents Ms. Anderson, said parts of her brain had received overdoses ranging from 25 percent to 100 percent.
A similar calibration problem involving a Brainlab and Varian unit was discovered in April 2007 at a hospital in Toulouse, France, where overdoses — smaller than those in Missouri — had occurred for a year, affecting 145 patients. These SRS treatments used tiny metal leaves to shape the beam.
“There were strong similarities between what happened in Missouri and what happened in Toulouse,” said Dr. Ola Holmberg, who heads the radiation protection unit for patients at the International Atomic Energy Agency.
But without a requirement that accidents and near-misses be reported, other hospitals cannot learn from these mistakes, Dr. Holmberg said.
“There is no effective way now of sharing the information or learning in a systematic way,” Dr. Holmberg said. “If something happens, such as Evanston, I would have wanted to know about it at the time.”
That point was echoed by Dr. Benjamin Movsas, chairman of the department of radiation oncology at Henry Ford Health System in Detroit. “I was not able to find any information about Evanston,” Dr. Movsas said. “It’s frustrating. We didn’t know there was a problem.”
Earlier this year, the American Society for Radiation Oncology called for the establishment of the nation’s first central database for the reporting of errors involving linear accelerators. So far that hasn’t happened.
“The system does need to change,” Dr. Movsas said. “Reporting needs to be transparent and mandatory.” He added: “We need regulations — that has to happen. It’s better for me and it’s better for my patients.”