Biophysical and Safety Aspects of Brain Photobiomodulation

This chapter delves into the biophysical principles and safety concerns associated with the use of photobiomodulation (PBM) for brain applications. It provides a comprehensive understanding of the different components involved in designing and implementing PBM treatments. Section 2.1 discusses various light sources used in PBM, including lasers, LEDs, and other types of devices. The advantages and disadvantages of each type are presented, along with their specific applications in brain PBM. Section 2.2 outlines the dosimetry and treatment parameters involved in PBM, including coherence, wavelength, power, irradiance, fluence, radiant energy, pulse mode of operation, beam area, beam profile, irradiation time, and treatment repetition regimen. Each parameter is described in detail, with an emphasis on their significance and influence on treatment outcomes. Section 3 focuses on the safety concerns related to brain PBM. The discussion begins with an overview of laser classes (Sect. 3.1), which categorize lasers based on their potential to cause biological harm. Section 3.2 addresses thermal effects and concerns, detailing the potential risks and precautionary measures associated with PBM-induced heating. Lastly, Sect. 3.3 presents the safety profiles of PBM in pre-clinical and clinical studies, highlighting the general safety and tolerability of the technique in various applications. This chapter provides readers with the necessary background knowledge to understand the principles, parameters, and safety aspects of brain PBM, ensuring a solid foundation for further exploration of the field.