On the Development of a Light Dosimetry Planning Tool for Photodynamic Therapy in Arbitrary Shaped Cavities: Initial Results

Abstract

Previous dosimetric studies during photodynamic therapy (PDT) of superficial lesions within a cavity such as the nasopharynx, demonstrated significant intra‐ and interpatient variations in fluence rate build‐up as a result of tissue surface re‐emitted and reflected photons, which depends on the optical properties. This scattering effect affects the response to PDT. Recently, a meta‐tetra(hydroxyphenyl)chlorin‐mediated PDT study of malignancies in the paranasal sinuses after salvage surgery was initiated. These geometries are complex in shape, with spatially varying optical properties. Therefore, preplanning and in vivo dosimetry is required to ensure an effective fluence delivered to the tumor. For this purpose, two 3D light distribution models were developed: first, a simple empirical model that directly calculates the fluence rate at the cavity surface using a simple linear function that includes the scatter contribution as function of the light source to surface distance. And second, an analytical model based on Lambert’s cosine law assuming a global diffuse reflectance constant. The models were evaluated by means of three 3D printed optical phantoms and one porcine tissue phantom. Predictive fluence rate distributions of both models are within ± 20% accurate and have the potential to determine the optimal source location and light source output power settings.

Fibroblast Activation Protein Targeted Photodynamic Therapy Selectively Kills Activated Skin Fibroblasts from Systemic Sclerosis Patients and Prevents Tissue Contraction

“…Cytotoxicity in tPDT is determined by an interplay of many complicated factors including light penetration in tissue, available oxygen, perfusion of the tissue as well as photostability of the antibody-photosensitizer construct. To optimize these parameters, dosimetry may be used, but, despite considerable effort, there are no standardized procedures yet to study these complex phenomena [ 22 ]. An especially important factor when studying PDT in fibrotic skin is the oxygen tension.…”

Photodynamic Therapy Targeting Macrophages Using IRDye700DX-Liposomes Decreases Experimental Arthritis Development

“…The transient nature of our therapy may also indicate that the treatment should be further optimized to give the best possible effect. Further optimization of the therapy could be achieved by performing light dosimetry, as well as by focusing on the timing of administration of the liposomes and subsequent light exposure [28,33]. Combining this therapy with low dose immunosuppressant therapy may also improve the longevity of the PDT effect.…”

Receptor-Targeted Photodynamic Therapy of Glucagon-Like Peptide 1 Receptor–Positive Lesions

“…Successful results of interstitial PDT have been obtained in, for example, prostate cancer (23), head and neck cancer (24), and, importantly, pancreatic tumors (25). An optimal treatment result depends on optimization of the number of light sources and of their specific placement and power output (26)(27)(28). With percutaneous delivery, areas up to 23 cm 2 can be treated (29), making the technique suitable for treatment of CHI and nesidioblastosis.…”