Dosimetry in PBM: the good, the bad, and the ugly

Photobiomodulation (PBM) research is riddled with errors in beam measurement, power calibration, and dose reporting. Many studies cite manufacturer data without independent validation, despite known power and beam area discrepancies. Beam profiling methods (e.g., FWHM, 1/e², 4Dσ) are rarely disclosed, even though these drastically alter calculated fluence. Inconsistencies multiply with LED arrays and beam clusters, while most papers fail to distinguish between surface dose (“radiant exposure”) and subsurface dose (“fluence”). These oversights undermine reproducibility and mislead clinical practice. This talk outlines key pitfalls in PBM parameter reporting and proposes a path to standardized, radiometrically accurate methods to restore credibility and consistency to the field. We recommend the ISO-compliant 4Dσ (second-moment) method as the most robust and universally applicable metric for beam area. This approach ensures consistency across beam shapes and wavelengths and lays a foundation for reproducible, clinically relevant PBM research.