Photodynamic therapy for glioblastoma: A preliminary approach for practical application of light propagation models

Abstract

Abstract:Purpose Photodynamic therapy (PDT) is a promising treatment modality to be added in the management of glioblastoma multiforme (GBM). Light distribution modeling is required for planning and optimizing PDT. Several models have been developed to predict the light propagation inside biological tissues. In the present study, two analytical methods of light propagation emitted from a cylindrical fiber source were evaluated: a discrete and a continuous method. MethodsThe two analytical approaches were compared according to their fluence rate results. Several cylindrical diffuse lengths were evaluated, and the relative deviation in the fluence rates was estimated. Moreover, a sensitivity analysis was conducted to compute the variance of each analytical model. ResultsThe discrete method provided fluence rate estimations closer to the Monte-Carlo simulations than the continuous method. The sensitivity study results did not reveal significant differences between the variance of the two analytical models.Conclusions Although the discrete model provides relevant light distribution, the heterogeneity of GBM tissues was not considered. With the improvement in parallel computing that drastically decreased the computing time, replacing the analytical model by a Monte-Carlo GPU-accelerated code appeared relevant to the GBM case. Nonetheless, the analytical modeling may still function in the optimization algorithms, which might be used in the Photodynamic treatment planning system.

Optimizing interstitial photodynamic therapy with custom cylindrical diffusers

“…For (B), the solid lines represent the white matter curves and the dashed lines represent the gray matter curves the brain. In general, these approaches aim to optimize the fluence rate [mW/cm 2 ] in the target volume [41,42], which was expanded in our previous study [12] to include a PDT dosimetry model, the photodynamic threshold model, in the cost function. A similar approach was introduced based on a direct reactive singlet oxygen dosimetry model by Lopez et al [43] using a graphical processing unit accelerated MC code.…”

“…A similar approach was introduced based on a direct reactive singlet oxygen dosimetry model by Lopez et al [43] using a graphical processing unit accelerated MC code. To allow rapid modeling, analytical models are often used as in the work of Dupont et al [41]. In this study, we have expanded on the recently introduced convex optimization approach for power allocation in iPDT planning [12] to include cylindrical diffusers with both flat and tailored emission profiles.…”

“…Various groups have developed iPDT treatment planning approaches for specific indications such as the prostate or the brain. In general, these approaches aim to optimize the fluence rate [mW/cm 2 ] in the target volume , which was expanded in our previous study to include a PDT dosimetry model, the photodynamic threshold model, in the cost function. A similar approach was introduced based on a direct reactive singlet oxygen dosimetry model by Lopez et al .…”

“…To allow rapid modeling, analytical models are often used as in the work of Dupont et al . . In this study, we have expanded on the recently introduced convex optimization approach for power allocation in iPDT planning to include cylindrical diffusers with both flat and tailored emission profiles.…”

Understanding the glioblastoma tumor biology to optimize photodynamic therapy: From molecular to cellular events

“…PDT can eliminate tumor cells through three well‐known mechanisms: (a) direct cell destruction to tumor cells by necrosis or apoptosis, (b) damage to blood vessels, variation in barrier function, constriction of arteriolar vessels, formation of thrombi and blood flow stasis, and (c) inflammation and activation of the immune response (Agostinis et al., 2011). Based on clinical trials that report the successful elimination of GBM in patients, the implementation and approval of PDT for high‐grade gliomas is a fact in a few countries (Akimoto, 2016; Dupont et al., 2018; Maruyama et al., 2016; Shimizu et al., 2018). Notably, recurrence usually occurs at the margin of the resection cavity, suggesting that selective cytotoxic local therapy through PDT might be of valuable interest to apply for (Schipmann et al., 2020).…”