4. Hart to Heart Ambulance Service Inc., Forest Hill, ambulance service provider, 9,200 beneficiaries and 234,311 services provided, received $5.7 million.

5. Prince George's County Fire Department, Upper Marlboro, ambulance service provider, 8,761 beneficiaries and 100,145 services provided, received $4.9 million.

6. Dr. Samer Saiedy, Lutherville, vascular surgery, 2,227 beneficiaries and 7,050 services provided, received about $4.7 million.

7. Dr. John Thompson, Towson, ophthalmology, 1,439 beneficiaries and 22,219 services provided, received $4.3 million.

8. Dr. Joseph Schwartz, Salisbury, ophthalmology, 2,556 beneficiaries and 29,587 services provided, received $4 million.

9. Baltimore Fire Department, Baltimore, ambulance service provider, 7,058 beneficiaries and 37,879 services provided, received $4 million

10. Dr. Ralph Boccia, Bethesda, hemotology/oncology, 757 beneficiaries and 454,343 services provided, received $4 million.

Note: Location reflects the Medicare billing address but providers might have multiple locations. Data also might reflect multiple providers billing under one provider's code.

Total Medicare payments in Maryland in 2012: $1.77 billion

Total providers: 18,508

Total specialties: 83

Average number of patients per provider: 383

Source: Centers for Medicare & Medicaid Services