Light dosimetry: status and prospects

Area of Science:

• Photomedicine and Photobiology
• Biophotonics
• Optical Engineering

Background:

• Light dosimetry is crucial for photomedicine and photobiology applications.
• Accurate measurement of radiant energy fluence rate is essential.
• Current theoretical models have limitations in predicting light distribution in tissues.

Purpose of the Study:

• To review the state of the art in light dosimetry for photomedicine and photobiology.
• To discuss theoretical models for analyzing optical data and calculating energy fluence rate.
• To highlight the importance of accurate optical constants and measurement techniques.

Main Methods:

• Discussion of theoretical models, including the two-flux model derived from transport theory.
• Explanation of the optical constants required for theoretical calculations: absorption, scattering, and scattering cosine.
• Description of quantitative measurement of energy fluence rate using fiber optic probes.

Main Results:

• The two-flux model shows similarities to heuristic models like Kubelka-Munk, indicating limitations.
• Accurate determination of all three optical constants is challenging and rarely achieved for tissues.
• Fiber optic probes enable quantitative measurement of energy fluence rate, allowing indirect determination of optical constants.

Conclusions:

• There is a need to move beyond heuristic models towards transport theory for accurate light dosimetry.
• Further research is required to compare methods for measuring optical constants and validate theoretical models.
• Understanding light energy fluence rate distribution in tissues is an ongoing area of research, with attention to boundary conditions.