Hundreds of brain cancer patients in the U.S. and France may be contacted about their radiation treatments from malfunctioning machines, which were ordered shut down by the French government after a manufacturer's warning.

The maker of the equipment, Brainlab of Munich, Germany, downplayed the risks and the company's founder said it involved a small targeting error that was unlikely to cause problems for patients. However, a company notification sent to a U.S. clinic warned the problem could cause "injury or death."

Some 550 Brainlab radiotherapy machines are in use worldwide — the largest number of them in the United States.

Brainlab officials said they believed the malfunction occurred in just seven models in use worldwide. Four hospitals in France, two in the United States and one in Spain have the equipment.

The Cleveland Clinic in Ohio said it uses the BrainLab machine. The hospital discontinued use of the machine after being notified of the problems last week, spokeswoman Eileen Sheil said.

Martin Weinhouse, a physics expert at Cleveland Clinic, said the problem involves a small aiming error that can occur when Brainlab's Novalis system is used with another manufacturer's head frame, a ring-shaped device that circles the head and is used in delivering radiation.

Weinhouse said the error involves a deviation of about 1.25 millimeters, which is similar to variations inherent in the delivery system anyway and he did not believe it would lead to serious problems.

Valley Medical Center in the Seattle suburb of Renton, Wash., was notified by Brainlab on June 5 and has discontinued its use of the machine, spokesman Perry Cooper said.

About 70 patients were treated with the machine in the past two years at Valley Medical, Cooper said, adding doctors were reviewing patients' records and notifying them of the defect. The hospital has not seen any problems with patients, Cooper said.

Brainlab founder and chief executive officer Stefan Vilsmeier told The Associated Press that because doctors typically allow a certain margin of error in targeting a tumor with radiation, "We don't expect any problems with the patients."

A copy of the notification sent to hospitals and dated June 4, was obtained by the Associated Press. It said the malfunction meant the "patient is set to an unintended position" when receiving radiation treatment and added: "This may cause serious injury or death to the patient."

The Food and Drug Administration regulates radiation therapy, but spokeswoman Julie Zawisza said the agency had no knowledge of the problem. FDA rules require that manufacturers promptly notify the agency of serious problems that could affect patient health.

Dr. Georges Noel, a radiotherapy expert at the Paul Strauss cancer center in Strasbourg, said machine malfunctions were potentially harmful.

"A mistargeted machine could irradiate healthy brain tissue ... It could kill healthy tissue," Noel said. Whether this would have a large or small effect on the patient depends on the part of the brain affected, he said.

In France, where there has been a rash of problems with radiotherapy, the Health Ministry this week ordered use of four of the country's eight radiotherapy machines suspended indefinitely following the warning that they were not targeting properly. All four were Brainlab models.

Radiotherapy treatment involves a one-time blast by a high-energy X-Ray that is aimed from several sources and focused on one point to kill the tumor. It typically has a margin of error of 0.8 millimeters when used on brain tumors.

In the malfunctioning French machines, the margin was found to have increased to 1.25 millimeters, Brainlab said in a statement.

"This security margin is always used to avoid critical organs: very important parts of the brain such as those that control sight," said Dr. Christian Carrie, coordinator of radiotherapy at the Leon Berard Cancer Center in Lyon.

Carrie said that with a security margin, "we cannot be sure, but we can hope" to avoid killing healthy brain tissue "even if there is a problem with the targeting of 1 millimeter."

Brainlab sent out its notification after it identified a calibration error in a new machine in Spain, Vilsmeier said. That machine has not yet been used on patients.

The problem was the second in France involving Brainlab machines in recent months. In April, 145 patients received an improper dose of radiation from Brainlab equipment in Toulouse in southern France. The company blamed the problem on a "calibration error" and French nuclear safety officials are investigating.

Brainlab says that problem was not connected to the latest malfunction with the radiotherapy machines.

Four hospitals, in Nancy, Tours, Montpellier and Paris, shut down their radiotherapy machines Monday and an analysis of the machines has begun.

The hospitals have also begun tracking down all patients who may have received treatment from the malfunctioning machines, a number that may top 620, reported Le Parisien newspaper.

Brainlab is offering a software update that should take care of the problem, Vilsmeier said.

In 2004 and 2005, 24 patients in Epinal received as much as a 30 percent overdose of radiation while undergoing prostate cancer treatment. Four of these patients died, and their families are suing the hospitals, claiming that the deaths were a result of the overdoses.

A 32 year-old woman died of complications after receiving a radiation treatment to an area 10 times the size she should have, in Lyon in 2004.

In both the Epinal and Lyon incidents, hospitals blamed the problems on human error.