Optimizing interstitial photodynamic therapy with custom cylindrical diffusers

Interstitial photodynamic therapy (iPDT) has shown promise recently as a minimally invasive cancer treatment, partially due to the development of non‐toxic photosensitizers in the absence of activation light. However, a major challenge in iPDT is the pre‐treatment planning process that specifies the...

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Bibliographic Details
Published in:Journal of biophotonics 2019-01, Vol.12 (1), p.e201800153-n/a
Main Authors: Yassine, Abdul‐Amir, Lilge, Lothar, Betz, Vaughn
Format: Article
Language:English
Subjects:
Cancer
Computer simulation
customized diffusers
Diffusers
Diffusion
Emission
Equipment Design
Glioblastoma
Light distribution
Optical Phenomena
optimization
Organs
Photochemotherapy - instrumentation
Photodynamic therapy
power allocation
Power management
Radiometry
Substantia alba
Substantia grisea
Tumors
Wavelengths
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Summary:Interstitial photodynamic therapy (iPDT) has shown promise recently as a minimally invasive cancer treatment, partially due to the development of non‐toxic photosensitizers in the absence of activation light. However, a major challenge in iPDT is the pre‐treatment planning process that specifies the number of diffusers needed, along with their positions and allocated powers, to confine the light distribution to the target volume as much as possible. In this work, a new power allocation algorithm for cylindrical light diffusers including those that can produce customized longitudinal (tailored) emission profiles is introduced. The proposed formulation is convex to guarantee the minimum over‐dose possible on the surrounding organs‐at‐risk. The impact of varying the diffuser lengths and penetration angles on the quality of the plan is evaluated. The results of this study are demonstrated for different photosensitizers activated at different wavelengths and simulated on virtual tumors modeling virtual glioblastoma multiforme cases. Results show that manufacturable cylindrical diffusers with tailored emission profiles can significantly outperform those with conventional flat profiles with an average damage reduction on white matter of 15% to 55% and on gray matter of 23% to 58%. Interstitial photodynamic therapy minimizes damage to organs at risk (OAR) when the illumination is well confined to the tumour. This work introduces a new convex optimization framework for PDT treatment planning that allocates power across a set of cylindrical light diffusers and also can customize the power emission profiles to further minimize OAR damage. Results show an average OAR damage reduction of 15%‐55% compared to conventional flat‐profile diffusers.
ISSN:1864-063X
1864-0648
DOI:10.1002/jbio.201800153