Photothermal Effects of High-Energy Photobiomodulation Therapies: An In Vitro Investigation

Mark Cronshaw ¹, Steven Parker ¹, Martin Grootveld ¹

⁰Leicester School of Pharmacy, De Montfort University, Leicester LE1 9BH, UK.

Biomedicines +

|

June 28, 2023

View abstract on PubMed

Summary

Photobiomodulation therapies (PBMT) using higher-power devices can cause significant tissue heating, especially with 980 nm lasers. Moving the laser source during treatment effectively reduces this temperature increase.

Area Of Science

Biomedical Engineering
Laser Physics
Photomedicine

Background

Photobiomodulation therapies (PBMT) are increasingly used clinically.
Higher-power devices with large applicators necessitate careful thermal management.
Understanding in vitro photothermal effects is crucial for safe clinical parameter development.

Purpose Of The Study

To investigate the in vitro photothermal effects of various laser wavelengths used in PBMT.
To compare thermal profiles between Flat-top and Gaussian beam devices.
To inform the development of safe clinical parameters for high-power PBMT devices.

Main Methods

In vitro experiments using porcine muscle tissue.
Thermographic measurements of surface and sub-surface temperatures.
Calibrated experiments with laser wavelengths from 650 nm to 1064 nm.
Comparison of Flat-top and Gaussian beam spatial distributions.
Statistical analysis using ANOVA.

Main Results

The 980 nm wavelength induced the highest temperature rise, followed by 1064 nm ≈ 650 nm >>> 810 nm (p < 5 × 10^-20).
All tested wavelengths, except 810 nm, exceeded a 6°C temperature increase threshold.
Optical scanning (moving the laser source) effectively mitigated temperature increases.

Conclusions

Specific laser wavelengths (e.g., 980 nm) pose a higher thermal risk in PBMT.
Exceeding thermal thresholds can be mitigated by techniques like optical scanning.
In vitro findings provide essential data for guiding safe clinical application of high-power PBMT devices.

Keywords:

dosimetry parameters photobiomodulation thermography