Background: Oral mucositis (OM) often occurs after myeloablative hematopoietic cell transplantation. We explore extra-oral photobiomodulation therapy (PBMT) for the prevention of OM in children. Objectives: Our objective was to use modeling of PBMT to determine optimal treatment sites and parameters for a safe and efficacious treatment. Methods: MRI images were analyzed to obtain morphological information on the extent of tissues along the six trajectories passing through the cheek; lips; submandibular and submental regions; neck, transversely and anteroposteriorly. For each treatment site we performed 18 simulations using morphological information from 18 subjects with ages between 5 and 20 years. The simulation technique uses Monte Carlo method to calculate light distribution and finite difference method to solve the heat transfer equation. Our model accounts for the geometry of emitter, optical, thermal, and morphological tissue properties, as well as possible changes of the optical properties during the therapy. We have used a layered tissue model. The optical and thermal properties of tissues were assigned to each pixel individually using published data on the properties of relevant tissues. We evaluated spatially resolved fluence rate, absorbed power, temperature increase and thermal damage. Results and Conclusions: At 850nm and 399mW/cm2, the median dose transmitted ranged from 0.18–2.4J/cm2. As presence of blood hinders light penetration, treatment sites should be chosen to avoid major blood vessels. There was no temperature increase and damage to the tissue. Our results reveal that extra-oral PBMT is safe and shows promise for the prevention of OM in children.
Anna N. Yaroslavsky, Wendy B. London, Christine Duncan, Amy F. Juliano, Steve T. Sonis, Ather Adnan, and Nathaniel S. Treister, "A Monte Carlo simulation of the dosimetry of extraorally delivered photobiomodulation therapy (Conference Presentation)," Proc. SPIE 10477, Mechanisms of Photobiomodulation Therapy XIII, 104770H (Presented at SPIE BiOS: January 27, 2018; Published: 14 March 2018); https://doi.org/10.1117/12.2295391.5751475993001.
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Monte Carlo based light propagation models to improve efficacy of biophotonics based therapeutics of hollow organs and solid tumours including photodynamic therapy and photobiomodulation (Conference Presentation)