A brachytherapy system for a target region includes an applicator having a plurality of channels that are hollow, where the applicator is implanted in the target region. The system further includes a tracking device, a tracking signal generator to generate a signal received by the tracking device, and a processor. The tracking device has a size and shape to be advanced and retracted through at least a portion of the plurality of channels. The processor can determine a position of one or more of the plurality of channels based on a movement of the tracking device. The processor can further determine the location of the plurality of channels in the images based on the position measurements from the tracking device.