Table 3.

Summary of the contribution of different energy sources in overcoming the limitations of PDT.

Energy Source	Contributions to Enhance the PDT
Microwaves	↑ Penetration depth ↑ Blood flow
Infrared light	↑ Penetration depth ↓ Phototoxicity in healthy tissues
X-ray	↑ Penetration depth
Ultrasound	↑ Penetration depth ↑ Precision in energy delivery
Electric field	↑ Transmembrane transport of PS and intracellular accumulation
Magnetic field	↑ Directional accumulation of PS in tumor cells ↓ Phototoxicity in healthy tissues