The top 1% of all physicians who billed Medicare in 2013—including 240 diagnostic radiologists—received 17.5% of the federal program’s total payments, according to the Wall Street Journal’s recent analysis of CMS data. That number is up from 16.6% in 2012.  

The data covers Medicare payments made to physicians and other healthcare professionals. It was released by CMS during the annual Health Datapalooza conference in Washington, D.C.

While 240 radiologists are included in that top 1%, radiology is far from the most represented specialty. More than 2,200 of the top 1% are hematologists and oncologists, and more than 1,600 are ophthalmologists.

The analysis lists some of the ways that physicians may end up billing Medicare for so much in a given year.

“The top billers ranged from doctors who specialize in treating the sickest, most complicated patients to those who expand their practices beyond treatment to bill costly laboratory tests or other add-on services,” the authors wrote. “In some cases, doctors’ payments soar as they acquire equipment—such as advanced imaging machines—that lets them bill for services they previously might have referred to hospitals.”

The practice of imaging center ownership, or office-based imaging, by radiology practices and the technical component payments associated with providing an imaging examination may have contributed to the seemingly grand sums attributed to the 240 radiologists. Needless to say, the costs of imaging center ownership were not included in the database.

The data also revealed that more than half of the payments billed to Medicare by the top 1% are for drugs, while 20% of the payments were for exams and evaluations. Labs and imaging tests made up 7% of the payments.

CMS has been busy making headlines with its data in recent weeks. In April, CMS released data on Medicare Part D prescription drugs prescribed by physicians and other healthcare professionals in 2013. Earlier this week, an announcement was made that “innovators and entrepreneurs” will soon be able to gain access to CMS Medicare data through a new policy.