The Dark Art of Light Measurement: Accurate Radiometry for Low-Level Light Therapy

March 2016 in “ Lasers in Medical Science ”

Mohammed Hadis, Siti Aishah Binti Zainal, Michelle J. Holder, James D. Carroll, Paul R. Cooper, Michael Milward, William M. Palin

low-level light therapy LLLT irradiation parameters wavelength power pulse frequency beam area irradiance exposure time radiant energy fluence photophysics light therapy

TLDR Most low-level light therapy studies did not accurately report how light was measured, affecting treatment reliability.

The 2016 review article analyzed the reporting of irradiation parameters in 74 low-level light therapy (LLLT) studies published between March 2014 and March 2015. It found that 73% of the articles did not report how light was measured and often relied on manufacturer-stated values, with missing information on key parameters such as wavelength, power, pulse frequency, beam area, irradiance, exposure time, radiant energy, and fluence. The review also noted frequent misuse of light property terminology and a general lack of understanding of photophysics, which could affect the repeatability, reliability of studies, and the efficacy of patient treatments. The authors recommended the inclusion of a physicist or skilled engineer in research teams and urged reviewers to reject papers that lack proper beam measurement methods and do not report all ten key parameters.

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