An applicator for delivering targeted radiation brachytherapy to tissue adjacent a cavity of a patient. The animal is a mammal, preferably a human or a rodent. Also provided is a method of fabricating such a tool. During the burst mode, the control circuit regulates a peak magnitude of the load current to the minimum rated current during a first time period, and stops regulating the load current during a second time period, such that the average magnitude of the load current is below the minimum rated current.