Judge Sean Cox made the ruling Tuesday, following a hearing in which prosecutors asked him to increase Dr. Farid Fata's $170,000 bond to $9 million, based on the assets available to him and his wife.
They fear Fata may try to flee the country.
Cox also ordered that Fata not practice medicine if he's released on bond.
Defense lawyer Christopher Andreoff wanted a much lower cash bond amount for Fata. He says his client is a U.S. citizen and not a flight risk.
The government says Fata ripped off Medicare by giving chemotherapy to patients who didn't need it and diagnosing cancer when it wasn't apparent.
Copyright 2013 The Associated Press.