Beam profile of the flashlamp pumped pulsed dye laser: support for overlap of exposure spots.

The degree to which individual practitioners overlap exposure spots of the flashlamp pumped pulsed dye laser when treating large vascular lesions appears to be a matter of personal preference. There are few data to support one approach over another. We have measured the beam profile of this laser at two different energy fluences using a photodiode and a digitizing storage oscilloscope. Results show that for each energy fluence, the beam intensity decreases from the center to the outside rim of the beam. A plot of beam intensity versus the radius of the treatment field approaches a truncated normal distribution with a full width at half-maximum of 4.7-4.8 mm. These results help explain why clinical overlap of exposure spots can be safely undertaken and provide a rationale for recommendations concerning the degree of overlap needed to expedite treatment while still minimizing adverse reactions.