A medical imaging system comprising: a microwave antenna array comprising a transmitting antenna and a plurality of receiving antennae, wherein the transmitting antenna is configured to transmit microwave signals so as to illuminate a body part of a patient and the receiving antennae are configured to receive the microwave signals following scattering within the body part； a processor configured to process the scattered microwave signals and generate an output indicative of the internal structure of the body part to identify a target within the body part； and a delivery device comprising a delivery needle for implanting a marker at the site of the target, the delivery device being movable relative to the microwave antenna array； wherein the receiving antennae are further configured to receive microwave signals scattered or emitted by the delivery needle and the processor is further configured to monitor a position of the delivery needle and to guide the delivery needle to the target within the body part.
