Table 1.

Photobiomodulation (PBM) parameters to be reported in clinical studies. Adapted from [54]

Category	Parameter	Unit	Explanation
Irradiation parameters	Wavelength	Nanometer (nm)	Light is packets of electromagnetic energy called photons that sometimes behave like particles but also have a wave-like property. Wavelength determines which chromophores will absorb the light. Light is visible in the 400–700-nm range. The energy of each photon is greater at short wavelengths than longer wavelengths; e.g., red light is ~2 elektronvolt (ev) per photon and blue light is ~3 ev.
	Power	Watt (W)	The number of photons per second. The higher the power the more photons emitted every second.
	Beam area	Centimeter squared (cm2)	The surface area of the beam on the patient. Also known as spot size. This is not always easy to determine because laser beams are usually more intense in the middle then fade towards the edge (Gaussian distribution) so it is hard to define where the exact edge of the beam is without special instruments. Many research authors do not report this parameter, let alone report it correctly.
	Aperture size	Centimeter squared (cm2)	The area of the light source tip. This is not necessarily identical as the beam area. The difference between the aperture size and beam area will be determined by the beam divergence and distance of the light source tip from the tissue.
	Irradiance (power density, or intensity)	Watts per centimeter squared (W/cm2)	Power (W) ÷ beam area (cm2). More irradiance could allow less treatment time; however, many studies have shown that if the irradiance is too high, treatment can be less effective even if the same total dose is delivered. The treatment guidelines suggest the safe and effective irradiance ranges.
	(Radiant) Energy	Joules (J)	Power (W) × time (s). More power could mean less treatment time; however, many studies have shown that too much power is less effective even if the same total energy is delivered. The treatment guidelines suggest the safe and effective energy ranges.
	Time	Second (s)	How long each treatment is applied at each location.
	Dosage (fluence or energy density)	Joules per centimeter squared (J/cm2)	Energy (J) ÷ beam area (cm2), or power (W) ÷ beam area (cm2) × time (s). Different outcomes can be obtained if the total dosage is delivered with high energy and short time or low energy and long time.
	Operating mode	Continuous wave (CW), pulsed	The continuity of the production of the output beam may be continuous or pulsed. There are several types of pulsed beam.
	Pulse structure	Second (s)	The durations of the pulse being on or off.
Treatment parameters	Physical relationship to the organ		Applicable when there is more than one way to approach the organ. For example, intra-oral device versus extra-oral device.
	Timing		Time of the treatment session relative to the cancer treatment.
	Treatment schedule		The frequency of treatments per day/week and the total number of treatments.
	Anatomical location		The anatomical site that was exposed to the light beam. If multiple locations were treated, all need to be described.