Table.

Characteristics of interstitial laser photocoagulation and photodynamic therapy

	Interstitial laser photocoagulation	Photodynamic therapy
Laser wavelength	Near infrared (805-1064 nm)	Red (630-730 nm)
Laser type	NdYAG	Diode
	Diode	Dye
Laser power (typical per fibre)	3-5 W	0.1-0.3 W (higher in hollow organs)
Nature of biological damage	Thermal	Photochemical
Effect on collagen and elastin	Destroyed	Largely unaffected
Inherent selectivity of necrosis between tumour and surrounding healthy tissue	None	Minimal (some selectivity between different layers of normal tissues)
Healing	Resorption and scarring	Regeneration, sometimes with scarring
Cumulative toxicity	None	None