Pulsed Versus Continuous-Wave 680 Nm Laser Light In Photosensitization By Chloroaluminum Phthalocyanine Tetrasulfonate

Long-pulse dye laser for photodynamic therapy: Investigations in vitro and in vivo

“…Pulsed light sources (e.g., flashlamp pumped dye lasers) may induce photon saturation effects of photosensitizers resulting in suboptimal photosensitization [19]. A saturation phenomenon could also explain the ineffective in vitro photosensitization of the aluminum sulfonated phthalocyanine when using a pulsed copper vapor pumped dye laser with a short pulse width of 9 ns [20]. However, a pulsed copper vapor pumped dye laser with a long pulse width of 2 s was comparable to a continuous wave argon ion pumped dye laser in an animal model using a phthalocyanine as photosensitizer [21].…”

“…Groups 3-18 were irradiated only at the specific wavelengths, whereas groups 19-34 were sensitized with ALA (3 mmol/l) and irradiated using different light sources (LPDL at 585 nm, 595 nm, or 600 nm vs. incoherent light source) and different light doses (10,20,30, or 50 J/cm 2 ).…”

“…A tunable long-pulse flashlamp-pumped pulsed dye laser (Sclerolaser, Candela Corp., Wayland, Massachusetts, USA, pulse duration 1.5 ms), at different wavelengths ( ‫ס‬ 585 nm, ‫ס‬ 595 nm, or ‫ס‬ 600 nm), and different light doses (10,20,30 For cell culture studies, 34 groups were formed (n ‫ס‬ 26 for each group). The first served as a control and received neither sensitizer nor irradiation.…”

Transient absorption changes in vivo during photodynamic therapy with pulsed-laser light

“…The results indicated that the depth of necrosis from light-activated sensitizer may be 1-5 mm greater with 10 ns pulsed-laser light in the range of 10 MW cm -2 , as compared to cw irradiation, depending upon the sensitizer and the tissue optical properties. These initial measurements (Pogue et al, 1997;Pogue et al, 1996) of our own and the previous studies of others (Cowled et al, 1984;McKenzie and Carruth, 1986;Ben-Hur et al, 1987;Ferrario et al, 1991;Shikowitz, 1992;Panjehpour et al, 1993;Rausch et al, 1993;Okunaka et al, 1992) mentioned above were the motivation for these in vivo measurements of light penetration, and comparisons of depth of necrosis in a rat s.c. tumour model, using BPD-MA as the sensitizer and comparing 10 ns pulses with cw irradiation.…”

“…This process allows the latter half of the pulse to pass through the surface layers with less attenuation (Patterson and Wilson, 1994). There have been several studies in recent years examining the use of pulsed lasers in PDT, which can be divided roughly into either physical chemistry-based research (Andreone et al, 1982;Andreone, 1987;Keir et al, 1987;Shea et al, 1990;Smith et al, 1994;Stiel et al, 1993), or phenomenologic biologic studies (Cowled et al, 1984;McKenzie and Carruth, 1986;Ben-Hur et al, 1987;Ferrario et al, 1991;Shikowitz, 1992;Panjehpour et al, 1993;Rausch et al, 1993;Okunaka et al, 1992;Pe et al, 1994). Several in vivo experimental papers have compared pulsed peak powers in the range of Transient absorption changes in vivo during photodynamic therapy with pulsed-laser light 100-1000 W cm -2 to cw irradiation with no significant difference in tissue treatment depth and no difference in clinical outcome for PDT (McKenzie and Carruth, 1986;Ferrario et al, 1991;Shikowitz, 1992;Panjehpour et al, 1993), yet studies with peak pulse powers above 10 5 W cm -1 have demonstrated increases in the PDT-affected tumour response rate (Rausch et al, 1993) and increase in the depth of necrosis (Okunaka et al, 1992) with pulsedlaser irradiation as compared to cw irradiation in PDT.…”