Increasing numbers of Americans are becoming too fat to fit into X-ray machines, US researchers report.
Some scans are unable to penetrate the excess fat
The nation's rising obesity problems mean many citizens are not only too large for scanners but they have too much fat for the rays to penetrate.
Over the past 15 years, the number of failed scans linked to patient obesity has doubled, Radiology journal reports.
The problem is not confined to scanners. UK hospitals have had to make their beds stronger for obese patients.
And airlines are designing aircraft to carry heavier loads because passengers are becoming plumper.
Dr Raul Uppot and colleagues, who work in radiology at Massachusetts General Hospital, had noticed that they were seeing more and more patients whose weight prevented them from having medical scans.
He and his team decided to look back at radiology reports between 1989 and 2003 to see the extent of the problem.
Year on year they saw a small but significant increase in the number of scans that had to be abandoned because the patient was too fat.
Ultrasound images were affected the most because the sound waves need to penetrate the skin and fatty tissue before reaching the organs being examined.
The study authors warned that important diagnoses could be missed if people could not be scanned.
The US government says 64% of the population are overweight.
Dr Colin Wayne of the UK's National Obesity Forum said the UK was showing a similar trend.
"The obesity rates in the US have been going up relentlessly. Sadly, in the UK we are following in their wake.
"The UK is now the fastest growing country in Europe for rising obesity.
"It's worrying if people can't get the necessary investigations. But that is just the tip of the iceberg. It is the epidemic of cardiovascular and metabolic diseases that will follow in the wake of obesity that is even more worrying."
Professor Adrian Dixon of the Royal College of Radiologists said: "It is a real problem and it is getting worse. People are getting fatter."
"One may not be able to offer the obese patient the best possible imaging test because of their weight," he added.