Table 2.

Characteristics and conclusions derived from empirical studies using pulsed light sources in superficial and I-PDT. T_ON stands for the pulse duration of the laser, PRR for the pulse repetition rate or frequency, φ for the average fluence rate and Φ for the average fluence. Adapted and updated from [97].

	Pulsed Light Source	Parameters	CW Light Source	Conclusions
[102,103]	Long-pulsed dye laser	λ = 585 nm TON = 1.5–40 ms PRR = 1 Hz Φ = 4–7.5 J/cm2	NA	Treatment of AKs using pulsed lasers following topical 5-ALA application is safe and effective.
[101]	Pulsed Dye Laser Broadband flashlamp filtered pulsed light	λ = 595 nm TON = 10 ms Φ = 7.5 J/cm2 λ = 500–650 nm TON = 20 ms Φ = 24 J/cm2	CW blue light φ = 10 mW/cm2	Pulsed light sources are capable of activation of PDT but produce dramatically less PDT reaction than the standard CW blue-light source.
[94]	Nd:YAG laser pumped optical parametric oscillator (OPO)	λ = 690 nm TON = 10 ns PRR = 10 Hz φ = 300 mW/cm2	Argon-laser + Dye; λ = 690 nm φ as pulsed	Pulsed irradiation allowed modest deeper light penetration in tissue.
[100]	Nd:YAG laser-pumped OPO	λ = 514.5 nm TON = 7–9 ns PRR = 10 Hz φ = 100 mW/cm2 Φ = 1 to 10 J/cm2	Argon-laser λ = 514.5 nm φ, Φ as pulsed	Dead cells irradiated by the pulsed laser light were induced through apoptosis. CW laser light irradiation led to necrosis.
[95]	Nd:YAG + OPO system	λ = 670 nm TON = 5 ns PRR= 30 Hz φ = 180 or 270 mW/cm2 Φ = 40 J/cm2	Diode laser λ = 670 nm φ, Φ as pulsed	Pulsed light caused suppressed oxygen consumption and lower cytotoxicity Pulsed light induced a lower decomposition rate of the PS
[96]	Ti:sapphire + optical parametric amplifier	λ = 630 nm TON = 70 fs PRR= 1 kHz φ = 74 mW/cm2 Φ = 150 J/cm2	Diode laser λ = 630 nm φ, Φ as pulsed	Twice as deep necrosis for ultra-fast pulsed laser using hematoporphyrin from Photogem®. Temperature increase <4 °C using a pulsed laser.
[99]	Diode pumped solid state yellow laser	λ = 584 nm TON = 15 ns PRR = 10 Hz φ = 160 mW/cm2 Φ = 140, 170 and 200 J/cm2	Diode Laser λ = 593 nm φ, Φ as pulsed	Pulsed mode mainly led to apoptotic cell death, while, in the case of CW mode, the cancer cells underwent necrosis. Similar photobleaching observed for both light sources
[98]	Semiconductor laser	λ = 670 nm TON = 200 ms Pulse repetition period = 700 ms φ = 2.5, 5, 10, 15 and 20 mW/cm2 Φ = 0.625 to 5 J/cm2	λ = 662 ±3 nm φ, Φ as pulsed	Pulsed promoted apoptotic cell death of k562 cells whereas CW induced necrotic cell death