A microwave ablation catheter (14) for use in a luminal network, comprising:a coaxial cable (36) configured to be coupled to a microwave energy source (16)；a distal radiating section (42) provided at the distal end (44) of the coaxial cable and configured to deliver microwave energy to tissue； andan elongated housing (23) defining a plurality of lumens in fluid communication with a fluid source (32), the plurality of lumens including:a first inflow lumen (19b) defined around the coaxial cable, the first inflow lumen configured to facilitate inflow of fluid to the distal radiating section；a second inflow lumen and at least one outflow lumen (19a') disposed around the first inflow lumen, the second inflow lumen (19c') configured to facilitate inflow of fluid to the distal radiating section, and the at least one outflow lumen configured to facilitate outflow of fluid from the distal radiating section.
