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Light distribution by linear diffusing sources for photodynamic therapy
L H Murrer1, J P Marijnissen, W M Star
1Department of Clinical Physics, Dr Daniel Den Hoed Cancer Centre, Erasmus University Hospital, Rotterdam, The Netherlands.
Physics in Medicine and Biology
|June 1, 1996
Summary
Linear light diffusers used in photodynamic therapy (PDT) emit light forward. This study reveals fluence rate in tissue is maximal near the diffuser tip, not the middle, due to scattering effects.
Area of Science:
- Biomedical Optics
- Photodynamic Therapy
Background:
- Linear diffusers are crucial for light delivery in photodynamic therapy (PDT).
- Understanding light distribution from these diffusers is key for effective treatment.
- The anisotropic emission of diffusers can affect light penetration in tissue.
Purpose of the Study:
- To investigate the angular light distribution of linear diffusers used in PDT.
- To predict light fluence rates in air and scattering media.
- To analyze how tissue scattering influences light distribution from diffusers.
Main Methods:
- Development of a device to measure angular light distribution at multiple points along the diffuser.
- Experimental measurements and computational predictions of fluence rates.
- Comparison of light distribution in air, a cavity, and a scattering tissue phantom.
Main Results:
- Light emission from linear diffusers is predominantly forward-scattered.
- Fluence rate in air and scattering tissue exhibits a maximum near the diffuser tip.
- In a purely scattering phantom, interstitial diffusers show maximal fluence in the bisecting plane, suggesting scattering cancels anisotropy.
Conclusions:
- Tissue scattering significantly impacts light distribution from linear diffusers in PDT.
- The forward-directed emission of diffusers is modulated by the optical properties of the surrounding medium.
- Accurate prediction of fluence rate requires considering both diffuser anisotropy and tissue scattering.