Patients exposed to high radiation levels

A machine's programming error caused the problem at Tampa's H. Lee Moffitt Cancer Center & Research Institute for 10 months.

Published April 1, 2005

TAMPA - An improperly installed machine exposed 77 patients with brain tumors and malformations to higher-than-prescribed radiation levels for nearly a year before the mistake was caught, officials at H. Lee Moffitt Cancer Center & Research Institute said on Friday.

Federal inspectors detected the error on March 7, after 10 months during which the machine had been used. They determined that the machine, installed in May, gave patients radiation doses 1.5 times more powerful than prescribed amounts.

"We at Moffitt take full responsibility for the programming error," said CEO/Center Director Dr. William Dalton in a Friday statement. "I'm sorry and all of us are sorry it happened."

Moffitt officials acknowledged the error more than three weeks after physicists with the Radiological Physics Center discovered it. The announcement's delay was necessary to allow time to meet privately with the patients, Dalton said in a telephone interview on Friday.

Of the 77 patients, two couldn't be reached by Moffitt because they were out of the country and 12 had died. Because of the serious nature of their conditions, the overexposure wasn't being blamed for any deaths or side effects observed in other patients.

"Some people were having side effects, but overall, they were within the normal range of side effects of radiation treatments," Dalton said. "We aren't seeing unanticipated levels of side effects."

An analysis of the patients showed that even with the increased dosages, only a third of the patients received radiation levels deemed by Moffitt officials to be unsafe, Dalton said.

Still, Dalton said he and his medical staff were concerned. The radiation was delivered to patients with brain tumors, and side effects to overexposure could include headaches and speech and memory loss. It could take three months to a year for these symptoms to emerge.

"Bottom line, we're talking about the difference between what we prescribed and what we delivered," he said. "There may be increased side effects."

Moffitt officials had high hopes for the new technology when they installed the new linear accelerator, which is used for non-invasive surgical treatment of tumors. The Novalis unit, by the German manufacturer BrainLab, shoots powerful beams of radiation at tumors. The pinpoint beams are narrow enough so as to minimize harm to healthy tissue.

Patients undergo 20 minutes of treatment rather than the usual days because the machine is so powerful and precise, Dalton said.

"Obviously, we were very excited," he said.

But, according to a report by the Florida Bureau of Radiation Control, a physicist installing the machine plugged in the wrong formula so that the machine would automatically release 50 percent more radiation than prescribed.

Why wasn't the mistake caught?

At first, both Dalton and Greenberg said, it was the fault of protocol that wasn't designed to catch calibration errors.

"We went above and beyond following protocol," Dalton said.