According to some embodiments, an ablation system or other treatment system comprises an elongate body, a first energy delivery member positioned along the distal end of the elongate body, and at least a second energy delivery member positioned at a location proximal to the first energy delivery member, the first energy delivery member and the second energy delivery member being configured to deliver energy sufficient to at least partially ablate tissue. In some embodiments, each of the first and second energy delivery members comprises an antenna configured to receive a microwave signal corresponding to a temperature of the tissue at a location adjacent the antenna. The system further comprises at least one radiometer configured to process the microwave signals received from the antennas of the energy delivery members and configured to produce an output signal representative of tissue temperatures at depth adjacent the first and second energy delivery members.