Fig. 9.

Photobiomodulation therapy (PBMT) of the knee. The delivery of 0.707 W of treatment light at 808-nm wavelength over a 3-cm-dia. spot yields an irradiance E = 0.100 ${\mathrm{W/cm}}^2$ , which penetrates into the knee to yield about 0.01 ${\mathrm{W/cm}}^2$ fluence in the soft tissue between the patella and bone.