Light therapy, also known as photobiomodulation, has shown promise in various medical applications, ranging from promoting wound healing and reducing inflammation to enhancing nerve cell regeneration. A crucial factor in achieving the desired therapeutic outcomes is the accurate dosing of light energy. This article will explore the importance of dosing in light therapy and present five influential research papers that have shaped our understanding of this topic.
Why Dosing is Key to Effective Light Therapy
Dosing in light therapy refers to the amount of light energy delivered to the target tissue, typically measured in joules per square centimeter (J/cm²). The optimal dosing varies depending on the specific condition being treated, the wavelength of light used, and the individual's unique physiology. The key reasons why dosing is critical to effective light therapy are:
- Biphasic dose response: Many biological processes, including the response to light therapy, follow a biphasic dose-response curve, meaning that both too little and too much light energy can be ineffective or even harmful. Optimal dosing is essential to achieve the desired therapeutic effect without causing adverse side effects.
- Penetration depth: The depth at which light penetrates the tissue is dependent on the wavelength and dosing. Accurate dosing ensures that the appropriate amount of light energy reaches the target tissue without being absorbed by superficial layers or overexposing (hot-spotting) the surrounding tissues. Using multiple treatment modules that can be placed around the target tissue is a great way to reduce this issue
- Individual variability: Each person's physiology is unique, and factors such as skin pigmentation, tissue density, and metabolic rate can affect how light energy is absorbed and utilized by the body. Accurate dosing accounts for these individual differences, ensuring that each person receives the optimal therapeutic effect.
Five Influential Research Papers on Light Therapy and Dosing
1. Hamblin, M. R., & Demidova, T. N. (2006). Mechanisms of low-level light therapy. Mechanisms of Low-Level Light Therapy, 6140, 614001.
This seminal review by Michael R. Hamblin and Tatiana N. Demidova discusses the various mechanisms of low-level light therapy, including the importance of dosing in achieving the desired therapeutic outcomes. The review provides a comprehensive overview of the current understanding of photobiomodulation and its clinical applications.
2. Huang, Y. Y., Sharma, S. K., Carroll, J., & Hamblin, M. R. (2011). Biphasic dose response in low-level light therapy – an update. Dose-Response, 9(4), 602-618.
This article by Ying-Ying Huang and colleagues presents an updated review of the biphasic dose response in low-level light therapy, emphasizing the importance of dosing in achieving optimal therapeutic outcomes. The authors discuss various factors that influence the dose-response relationship and provide guidelines for selecting the appropriate dosing parameters in clinical practice.
3. Barolet, D., & Boucher, A. (2016). Procedural learning and anxiety reduction using a novel handheld dynamic phototherapy device. Lasers in Surgery and Medicine, 48(4), 336-342.
This study by Daniel Barolet and Annick Boucher explores the procedural learning and anxiety reduction achieved using a novel handheld dynamic phototherapy device, demonstrating the importance of dosing in achieving these therapeutic effects. The authors present a new approach to dosing that considers both the energy density and the dynamic aspects of light delivery.
4. Lanzafame, R. J., Blanche, R. R., Chiacchierini, R. P., Kazmirek, E. R., & Sklar, J. A. (2004). The growth of human scalp hair mediated by visible red light laser and LED sources in males. Lasers in Surgery and Medicine, 36(4), 294-297.
In this study, Raymond J. Lanzafame and colleagues investigate the effects of red light laser and LED sources on human scalp hair growth in males. The authors emphasize the importance of dosing in achieving significant hair growth stimulation, providing valuable insights into the optimal dosing parameters for this specific application of light therapy.
5. Amaroli A, Arany P, Pasquale C, Benedicenti S, Bosco A, Ravera S. Improving Consistency of Photobiomodulation Therapy: A Novel Flat-Top Beam Hand-Piece versus Standard Gaussian Probes on Mitochondrial Activity. International Journal of Molecular Sciences. 2021; 22(15):7788.
This article covers a specific dosing consideration, beam shaping. A conventional laser has a gaussian beam shape, meaning that the intensity of light is not distributed evenly across the illuminated area. The authors investigate the use of a more homogenous beam shape to achieve more consistent mitochondrial activation. While this may seem like a small factor, there are many details like this that all contribute to the quality of photobiomodulation treatment.
The research papers presented in this article emphasize the critical role of dosing in achieving the desired therapeutic outcomes with light therapy. An understanding of the biphasic dose-response curve, penetration depth, and individual variability is essential for clinicians and researchers to determine the optimal dosing parameters for specific conditions and applications. As our knowledge of the mechanisms and applications of light therapy continues to expand, accurate dosing will remain a key factor in unlocking the full potential of photobiomodulation for a wide range of medical conditions.
For more on the science and reserach behind red light therapy, read: