A light dose is more than one number on a device. Researchers are asked to report a set of beam parameters: wavelength, power, irradiation time, beam area at the skin, pulse settings, location on the body, number of sessions, and the time between them. The three dose figures most often used are time, energy, and energy density (Jenkins & Carroll, 2011).
Two terms carry most of the meaning. Irradiance, also called power density, is power spread over an area, usually written in milliwatts per square centimeter. Fluence, also called energy density, is energy delivered over an area, usually written in joules per square centimeter (de Freitas & Hamblin, 2016). Fluence is irradiance multiplied by time.
Dose matters because photobiomodulation follows a biphasic dose response. Too little light may do nothing, and too much can produce unwanted inhibitory effects (de Freitas & Hamblin, 2016; Huang et al., 2009).
Power also drifts. A device’s output often falls as it warms up and as it ages, so careful studies measure it before, during, and after a trial (Jenkins & Carroll, 2011).
How we use it
We have not measured the light dose a person receives inside our installations, so we make no therapeutic dose claim for them.
References
de Freitas, L. F., & Hamblin, M. R. (2016). Proposed mechanisms of photobiomodulation or low-level light therapy. IEEE Journal of Selected Topics in Quantum Electronics, 22(3), 348–364. https://doi.org/10.1109/JSTQE.2016.2561201
Huang, Y.-Y., Chen, A. C.-H., Carroll, J. D., & Hamblin, M. R. (2009). Biphasic dose response in low level light therapy. Dose-Response, 7(4), 358–383. https://doi.org/10.2203/dose-response.09-027.Hamblin
Jenkins, P. A., & Carroll, J. D. (2011). How to report low-level laser therapy (LLLT)/photomedicine dose and beam parameters in clinical and laboratory studies. Photomedicine and Laser Surgery, 29(12), 785–787. https://doi.org/10.1089/pho.2011.9895