New X-ray reduces radiation

New X-ray reduces radiation

May 19, 2010

Rady Children’s Hospital in San Diego is the first medical center on the West Coast, and one of five in the country, to offer a new X-ray machine that reduces radiation exposure by as much as 90 percent.

Doctors at the facility said the EOS device has some limitations, but is particularly useful for treating youngsters with spinal deformities, such as scoliosis, that need repeated X-rays over a number of years. At hospitals caring for adults, the machine is mainly reserved for patients with degenerative bone diseases and other problems requiring hip or joint replacement.  EOS isn’t an alternative for CT scans, which enable physicians to look inside organs and other body tissue. High levels of radiation can increase a person’s chances of developing certain kinds of cancers later in life. While the exposure risks are greatest with CT scans, repeated X-rays also can pose a danger.

Medical devices account for about half of the radiation exposure received by Americans each year, according to a 2009 report from the National Council on Radiation Protection and Measurements. X-ray machines deliver about 5 percent of that amount.  Children are especially vulnerable because significant radiation can damage their cells while their bodies are still growing, said Dr. Kimberly Applegate of Atlanta, a pediatric radiologist who heads the American College of Radiology’s guidelines and standards committee.  EOS “is one small piece of a very large puzzle,” Applegate said Tuesday. “But there is no doubt that every little bit helps.”

A scoliosis patient diagnosed at age 8 might get two X-rays every six months for several years as doctors monitor the progress of the spine-twisting affliction while the child grows, said Dr. Peter Newton, an orthopedic surgeon at Rady.  “If we can give them 25 X-rays (with EOS) for the radiation exposure of two or three (conventional X-rays), then that’s quite a difference,” he said.

The Rady staff installed the EOS machine less than two weeks ago. Each unit sells for about $500,000, comparable to the price tag for an upper-end conventional X-ray machine or a lower-end CT scanner, said the device’s maker, biospace med of Paris.  Two innovations allow EOS to capture information while emitting significantly less radiation.  The device, which is about the size of a closet, scans a standing patient from the front and back with a pair of thin, horizontal X-ray beams. In comparison, conventional X-ray machines expose larger areas of the body to a single blanket of radioactive particles.

EOS also uses a patented detection technology that requires fewer radioactive particles to produce a high-resolution, three-dimensional image.  While radiologists generally embrace new technologies that reduce radiation risks, they’re still unsure about the exact long-term consequences for children exposed to high amounts of radiation.

Five major studies, each involving 200,000 or more children, are under way outside the United States. Those researchers are likely years away from drawing conclusions because their projects are designed for long-term observation.  As part of a growing effort to reduce radiation exposure, the American College of Radiology and a few other related professional organizations launched the Image Gently campaign in 2008 to increase awareness about CT scans performed on children.  Svetlana Zanetti of La Jolla said she began worrying about radiation exposure shortly after her daughter Camilla was diagnosed with scoliosis last year.  “I am very concerned about environmental causes of many diseases, and causes of cancer are very important to us,” said Zanetti, a neuropsychologist who is married to a physician.

Doctors at Rady probably will monitor Camilla, now 10, for the next five years while she wears a brace to counteract the effects of her condition, Zanetti said. The girl will need a new set of X-rays every six months.  “So it’s a lot,” her mother said.  Camilla is scheduled to undergo her first EOS scan today.

The technology that made the new device possible was rooted in the work of Georges Charpak, a French physicist of Polish descent who won the Nobel Prize in physics in 1992 for his particle detector research, said Marie Meynadier, CEO of biospace med. Charpak is a shareholder of the French company, she said.  Newton, the orthopedic surgeon, said he learned about EOS several years ago from colleagues in Montreal who were testing early versions of the machine.  “A lot of what attracted me was the X-ray dose reduction,” Newton said. “Secondarily, it had this spectacular advantage to gather data (in three dimensions) that could help us change the way we think about and treat children with scoliosis.”

More imaging advancements aimed at lowering radiation levels are on the way, said Applegate of Atlanta.  Some companies are working on software that displays a warning on CT scanners’ control terminals when radiation exposure settings exceed safety guidelines, she said.  Other innovators are developing CT scans that beam radioactive particles only at the back of the patient to protect sensitive organs in the front of the body, including the thyroid, breasts and gonads.  “The (device) vendors are being pushed by regulators and the manufacturers association, and Congress held hearings in the past year,” Applegate said. “They are starting to say, ‘What can we do?’?”

Keith Darcé: (619) 293-1020;