Scientists say the particle accelerators target cancer cells more accurately than X-rays, The New York Times reported Tuesday. But some experts say the rush to newer, more expensive technology -- which can cost more than $100 million a pop -- is what is pushing the high cost of healthcare in the United States, the Times said.

"I'm fascinated and horrified by the way it's developing," said Anthony L. Zietman, a radiation oncologist at Harvard and Massachusetts General Hospital, which operates a proton center. "This is the dark side of American medicine."

Proponents say the accelerators will ultimately mean better treatment for cancer patients. More than 800,000 Americans undergo radiation therapy each year.

"Every X-ray beam I use puts most of the dose where I don't want it," said Dr. Jerry D. Slater, head of radiation medicine at Loma Linda University Medical Center in California.

But opponents say the newest form of X-rays diminish any advantages from proton therapy.

"There are no solid clinical data that protons are better," said Dr. Theodore S. Lawrence, chairman of radiation oncology at the University of Michigan.