title: A system to monitor for fibre breakage during photodynamic therapy with diffuser fibres.
abstract: There is concern that the delicate fibres and cylindrical diffuser tips used for intraluminal PDT of blood vessels might break during the treatment. We have developed and tested a simple system to monitor for fibre breakage during PDT. Light from the laser is passed through a beam expander, then a beam splitter, and then is again contracted into the inlet of a diffuser fibre. Light reflected from the distal diffuser is also partially reflected by the beam splitter into a photodiode, which monitors changes in the intensity of the reflected light. The system was tested by simulating catastrophic failures in four fibres. In each case the output fell very significantly (DV=0.44-1.68 V, SD=0.01 V). Despite the small statistical sample, the average change in the reflected light intensity is still significant (p < 0.025, paired Student's t-test). Our conclusion was that this device can monitor the integrity of diffuser fibres during PDT.
mesh_terms: D000818:Animals; D004867:Equipment Design; D004868:Equipment Failure; D019544:Equipment Failure Analysis; D010778:Photochemotherapy / Q000009:adverse effects / Q000295:instrumentation*; D013552:Swine