The Use of a Pulsed Dye Laser for Identification of Urinary Stone Composition
Various methods can be used to identify the composition of urinary tract stones. Although these are reliable, they tend to be time-consuming and are applicable only to stones in vitro. The pulsed dye laser, however, offers the possibility of stone composition analysis simultaneously with disintegration of the same stone. This might be of benefit as some stones are known to resist laser lithotripsy. When a pulsed dye laser is fired onto the surface of a stone immersed in liquid, some of the laser light is ‘absorbed’ onto the stone resulting in the formation of a plasma field. The events occurring in this plasma field are poorly understood but two useful side effects occur: the first is the formation of a shock wave which may cause disintegration of the stone; the second effect is the stimulation of the atoms and molecules of the stone to fluoresce. The study of this fluorescence should give, therefore, a qualitative analysis of the stone composition.