1. A method of brachytherapy, the method comprising the acts of: positioning an applicator into a target region at an initial position in accordance with an initial brachytherapy plan, the applicator having a plurality of hollow channels subject to a shifting of position during use; generating signals by a generator; moving a tracking device through at least a portion of the plurality of hollow channels, wherein the tracking device includes more than one receiving coil or antenna configured to receive signals from the generator; acquiring position measurements from the tracking device based on characteristics of the signals received by the tracking device during movement of the tracking device through the at least a portion of the plurality of hollow channels; obtaining a shifted position of one or more of the plurality of hollow channels by comparing the position measurements acquired during the movement of the tracking device through the at least a portion of the plurality of hollow channels to the initial position; localizing the shifted position of the one or more of the plurality of hollow channels in an image using the position measurements from the tracking device; positioning a radioactive seed in one of the plurality of hollow channels to provide a radiation dose, wherein a seed sensor is coupled to the radioactive seed to confirm a seed position of the radioactive seed, and wherein the seed sensor is provided in addition to the tracking device; and updating the initial brachytherapy plan by a processor for administering the radiation dose based on the shifted position of the one or more of the plurality of hollow channels.