As Americans get heavier and heavier, medical imaging machines are having a hard time peering inside their bodies, doctors reported on Wednesday.

“Hospital radiology departments are increasingly unable to adequately image and assess obese patients because of the limitations in current radiology equipment,” said Raul Uppot, a physician at Massachusetts General Hospital in Boston.

Equipment makers “need to think about design changes and technological advancements to obtain quality imaging in larger patients,” he added.

“In the meantime, radiologists need to be aware of the limitations of their current imaging equipment and optimize current protocols and equipment settings to accommodate America’s fattening population,” Uppot said.

He and colleagues released their report at the annual meeting of the Radiological Society of North America. It was based on a review of 15 years of radiologic exams at the Boston hospital that had been labeled as being of limited use because of body size.

The percentage of such reports nearly doubled over the period, the researchers said, and corresponded to increases in obesity in the United States. Over the 15 years, obesity increased in Massachusetts from 9 percent of the population to 16 percent.

The biggest problems were with abdominal ultrasound followed by chest X-ray and abdominal computed tomography, the report said.

More than 60 percent of Americans are overweight or obese, with a much higher risk of heart disease, stroke, diabetes and some cancers than people of healthy weight.

The American Obesity Association estimates that 127 million people in the United States are overweight, 60 million are obese, and 9 million are severely obese.