DEVELOPMENT OF AN ALTERNATIVE LIGHT-SOURCE TO LASERS FOR PHOTODYNAMICTHERAPY .2. COMPARATIVE IN-VIVO TUMOR RESPONSE CHARACTERISTICS

The performance of a low cost, table-top/portable light source was tes ted against an argon ion pumped dye laser for in vivo photodynamic the rapy (PDT). The prototype delivers up to 1 W via a 4 mm flexible light guide within a 30 nm bandwidth centred at any wavelength from 300 nm t o 1200 nm at fluence rates of up to 8 W cm(-2). An in situ bioassay us ing regrowth delay of tumour T50/80 was used to quantify the relative efficacy of the prototype with a laser. The tumours were sensitized wi th haematoporphyrin derivative (HpD) and externally irradiated. There was no significant difference in the response of the tumour to treatme nt between the two light sources (p=0.69). Mean growth delays ranged f rom 2 days (light dose 10 J cm(-2)) to 20 days (light dose 100 J cm(-2 )). The estimate for the difference in means (laser minus prototype gr owth delay) was only 0.66 days and was not statistically significant. This in vivo study demonstrates that the prototype is equivalent to a laser in PDT effect. The device has low capital/running cost, is simpl e to use and is one of the most powerful, spectrally efficient non-las er PDT sources available.