It's a rather mind-boggling breakthrough considering radiologists normally work on $100,000, customized workstations made by the likes of Philips Medical Systems or McKesson Information Solutions. The price has severely limited the number of stations available, Ratib says, which means specialists may be wasting time running down to another department to view a scan. With OsiriX, they can now use desktop computers for diagnostics.

The pair started working on OsiriX in December 20003, and within a few months, decided to release their creation into the world. Silently and with no fanfare, they posted the application on their website in April 2004. In less than two months, they'd racked up several thousand page views and received scores of emails from interested doctors.

Dr. Michael L. Richardson, a radiologist and professor with University of Washington's Medical Center, had been following Ratib and Rosset's work for several years. As soon as he found about the OsiriX, he downloaded a version of the software.

Based on a Web-based survey Ratib conducted last year, he believes Richardson is one of some 6,000 doctors around the globe using the tool. But what shocked even Ratib is the way OsiriX has spread. What started a tool for radiologists, has found its way into other parts of the hospital.

The same survey of 2,000 users indicates that while OsiriX has found its largest following among radiologists -- who make up 26 percent of its users -- researchers (18 percent), surgeons (14 percent), and cardiologists (12 percent) are also tinkering with the application.

But it's not just a novelty, a one-time joyride for medical hackers. Thirty-seven percent of the respondents say they use it every day, and 24 percent say they are likely to develop plug-ins or other upgrades to better serve their needs.

While critics have leveled criticism about the iPod application, Ratib says that the patient's personal data is stripped out and assigned an anonymous identification during transport.

"It's not an issue of what technology you use," Ratib says, "but what you do with it."