In a system and method for x-ray brachytherapy, a probe is introduced into the body of a subject, the probe carrying an x-ray source that radiates x-rays into an exposure area outside of the probe within the body of the subject. A number of markers are located in or on the probe, that are detectable in an image generated by an imaging device. The markers are located in or on the probe in a known spatial relation to the exposure area, so that the position of the exposure area can be determined by identifying the markers in the displayed image.
