Biophotonics_Concepts_to_Applications

Table 6.3

Summary for six generic laser-tissue interaction effects

Interaction mode

Tissue effect

Typical sources Exposure time

Irradiancelevels

Applications

Photobiomodulation Photochemical effects

600

• 1100 nm
  lasers and LEDs

30 s

-^10

3 s treatments

with pulsed or CW light

1 mW/cm

2

to

1 W/cm

2

Heal tissue, nerve injuries, wounds;reduce in

flammation and pain

Photochemical

Photochemical effects

Red LEDs orlasers

500 ms

• 600 s

100 mW/cm

2

to 80 W/cm

2

Photodynamic therapy

Thermal

Local changes in tissue temperatureproduce various effects

CO

, Nd:YAG, 2

Er:YAG

50

μs

• 10 s

10

-^10

5 W/cm

2

Coagulation, vaporization

Photoablation

UV photons used to breakmolecular bonds; precise ablation

ArF, KrF, XeCl 1 ns

-^1

μs10

7 –

10

11

W/cm

2

Ophthalmology

Plasma-inducedablation

Very clean ablation from an ionizedplasma

Nd:YAG

100 fs to 500 ps

10

10

-^10

13

W/cm

2

Ophthalmology, caries therapy

Photodisruption

Cutting and fragmentation of tissueby mechanical forces

Nd:YAG,Ti-sapphire

10 fs to 200 ps

10

11

-^10

16

W/cm

2

Lithotripsy, ophthalmology

6.5 Light-Tissue Interaction Mechanisms 175