B737-900
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Situational Awareness
Conflict Ground Conflict; Critical; Ground Event / Encounter Vehicle
Flight Crew Took Evasive Action
Human Factors; Procedure; Airport; Environment - Non Weather Related
Large fuel truck; possibly # (NUMBER) came around the end of the concourse and into the alley as we were taxiing outbound. The fuel truck stayed outside of the protected white and in the aircraft lane until abeam the nose of our aircraft. In the meantime we we were given taxi clearance out of the alleyway and were rolling. The fuel truck then darted towards our wingtip but did not cross the white line to the protected area. From my vantage point; I did not think there was sufficient clearance and had to slam on the brakes.  Incident reported to Ramp Control (they did not care).Reported to ZZZ Ops.We checked with cabin crew to see if we had any injuries (none).Recommend full size aircraft only enter and exit this alley way on center line if Ground Ops vehicles continue to ignore protected area white line on ramp and continue to drive around our wing while on the east line. I cannot determine clearance of wingtip from flight deck of these vehicles driving around wing.
Captain reported hard braking to avoid collision with a fuel truck being operated outside of the vehicle access roads in the gate area.