An apparatus and method for exposing a treatment site in a patient to x-ray radiation is described that uses a pulse voltage source, where the x-ray emitter employs a cold cathode. The invention may further include a current sensor for measuring a current through the x-ray emitter, and, optionally, a current integrator connected to the current sensor. Each voltage pulse may be discontinued when a predetermined amount of charge has passed through the emitter. The step of moving an x-ray emitter past a treatment area at a rate determined by the amount of charge that has passed through the emitter is also described. The present invention also includes an x-ray emitter device with rectangular voltage pulses added to a base direct current voltage. Another step of the invention may be applying a voltage pulse cycle to the x-ray emitter where a duration of the pulse is 2-5 times lower than a thermal relaxation time of an emitter.