Table 1.

Comparison of various light sources used in photodynamic therapy and their main advantages and disadvantages.

Light Source	Description	References
Sun light	The use of sunlight as a treatment for dermatological conditions such as actinic keratosis is a cost-free and less painful option that can be easily performed at home. However, it is highly dependent on the weather conditions of the region, and there is no way to regulate the amount of energy emitted.	[88,89]
Lamp lights	Lamp lights are cheap, portable, easy to use, and emit at a wide range of wavelengths. In addition, filters eliminate radiation emitted without interest in the excitation of the photosensitizer, namely at short wavelengths. However, they have the disadvantage of losing energy in the form of heat, which is why they emit low-intensity light and are mainly limited to treating dermatological diseases.	[84]
Light-emitting diodes (LEDs)	LEDs are light sources with high power stability, capable of irradiating large areas, thermally non-destructive, inexpensive, small in size, and easily transportable. Combining lamps emitting at different wavelengths to excite several photosensitizers is possible with the same equipment. The light is incoherent and polychromatic, emitting in a narrow region of the electromagnetic spectrum.	[90,91]
Lasers	Lasers are currently the most commonly used clinically and produce high-intensity, coherent monochromatic light. The coherence contributes to the precise control of the fluence applied to the target tissue, which is more difficult to assess using incoherent sources. They can be coupled to optical fibers to deliver light to highly inaccessible tissues. It is the most expensive light source compared to those above. Comparative studies show comparable photodynamic efficacy using lasers or LEDs.	[78,84,92,93]