5-ALA Photodynamic Therapy in Neurosurgery, Towards the Design of a Treatment Planning System: A Proof of Concept

• Published in: Ingénierie et recherche biomédicale Vol. 38; no. 1; pp. 34 - 41
• Main Authors: Dupont, C, Betrouni, N, Mordon, S.R, Reyns, N, Vermandel, M
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 01.02.2017; Elsevier Masson
• Subjects: Cancer; Internal Medicine; Life Sciences; 5-Aminolevulinic Acid; 5-ALA Photodynamic Therapy; Dosimetry; Simulation; Treatment Planning System; Glioblastoma
• ISSN: 1959-0318
• DOI: 10.1016/j.irbm.2016.11.002

Abstract Purpose. Glioblastoma (GBM) treatment still remains a complex challenge. Among alternatives or adjuvant therapies, photodynamic therapy (5-ALA PDT) appears to be a promising approach. 5-ALA PDT can be delivered intraoperatively, early after tumor resection, or interstitially according to brain tumor location. A treatment planning system was designed to manage dosimetry issues before PDT delivery. Methods. The TPS was developed according to a specific workflow from stereotactic image registration to light fluence rate modeling. Here, we describe a proof of concept of a treatment planning system (TPS) dedicated to interstitial 5-ALA PDT. This tool enables the planning of a whole treatment in surgical stereotactic conditions. Stereotactic registration and dosimetry components are detailed and evaluated. The registration process is compared to a commercial solution (Leksell Gamma Plan® , Elekta® , Sweden) defined as the ground truth and dosimetry model implemented in our TPS and is compared to numerical simulations. Results. Registration achieved a sub-millimetric mean relative error that matched the standard MRI resolution. Dosimetry comparison showed a negligible error between analytical and numerical models and enabled a validation of the dosimetry algorithm implemented. Conclusions. A treatment planning system was designed to achieve 5-ALA PDT simulations before the patients underwent surgery. Similarly, for radiation therapy, we proposed a system to plan and evaluate the 5-ALA PDT dosimetry for optimizing treatment delivery. Although this system remains to be perfected, this preliminary work aimed to demonstrate the feasibility of planning 5-ALA PDT treatments in stereotactic conditions. Future improvements will mainly focus on the optimization of the treatment delivery, automatic segmentation and GPU-accelerated Monte-Carlo management to take into account GBM tissue heterogeneity.