Method and x-ray device using adaptable power source

The present invention relates to an apparatus and method for exposing a treatment area in a passage inside a patient to x-ray radiation. In particular, the invention relates to a method and apparatus for x-ray treatment using an adaptable voltage source to an x-ray emitter. A method described includes positioning an x-ray emitter at a treatment area, where the x-ray emitter is connected to a cable, setting a voltage source at a source voltage, and measuring a current through the x-ray emitter. The method may include comparing a current flowing through the emitter with a limit and a low limit. The method further includes increasing the source voltage if the current is higher than the high limit. The method includes determining the high limit and the low limit based on the source voltage and the desired radiation. An apparatus of the invention includes an x-ray emitter with a voltage source and a current sensor. The apparatus may include a current comparison device for comparing the measured current with a high limit and a low limit, and further include a voltage source control. A current integrator for integrating a current from the x-ray emitter may also be included.