Observation of ultrasonic emission from edges of therapeutic X-ray beams

Describes the observation of acoustic pulses generated solely by the dose gradient at the edges of a therapeutic X-ray beam in a medium consisting only of water. This effect might find application when soft-tissue regions of patients receive therapeutic X-ray doses, either to verify precisely the position of the delivered X-ray dose relative to critical tissue which must be spared as much as possible during a course of treatments, or to measure a physical characteristic of the tissue.