COSAM » Events » 2017 » February » Physics Colloquium - Biophysical investigation of photodynamic therapy

Physics Colloquium - Biophysical investigation of photodynamic therapy
Time: Feb 24, 2017 (03:00 PM)
Location: 236 Parker Hall - Snacks in 200 Allison at 2:45 pm



February 24, 2017

Biophysical investigation of photodynamic therapy


 Dr. Rozhin Penjweini

Dept. of Radiation Oncology, School of Medicine, Univ. of Pennsylvania


Photodynamic therapy (PDT) is an evolving treatment modality for many cancerous, non-cancerous and premalignant diseases. PDT is not only “dynamic” but also multifaceted. There are three principal components of a photosensitizing drug (photosensitizer), light (mostly in visible and infrared regions), and oxygen (3O2), all of which interact on time scales relevant to a single treatment. Most photosensitizers used in the clinic are of the type II category, which produce singlet oxygen (1O2) as the main cytotoxic agent. The treatments that lead to production of higher 1O2 concentrations are more apt to produce a complete response to PDT. So far, studies have shown that PDT is both effective and associated with fewer non-specific toxicities than other conventional treatments such as surgery, chemotherapy, and ionizing radiation. However, widespread use of PDT has been stilted due to the difficulty in accurately quantifying the delivered dose. We also have limited understanding of how photosensitizers interact with tumor cells to modulate molecular and traficking processes that influence cancer cell growth and survival. Understanding these specific interactions and the way in which the mechanisms of action of these photosensitizers may be altered by their physiochemical properties represents a critical gap in knowledge. Herein, a multi-disciplinary approach is used to determine the intracellular trafficking, localization, dynamics, and toxicity of different photosensitizers. The distribution of photosensitizer and oxygen is modeled as a diffusion process through the vasculature. The distribution of light in tumor is determined by the light source characteristics and the tissue optical properties using Monte Carlo simulation. Then, singlet oxygen concentration is calculated based on the explicit dosimetry of the components, photosensitizer, light, and oxygen to evaluate the outcomes of a type II PDT in mice models bearing radiation-induced fibrosarcoma (RIF) tumors.


Friday, February 24, 2017

2:45 PM – Allison Lab Rm. 200 – Refreshments

3:00 PM – Parker Hall Rm. 236 – Colloquium

Last updated: 02/20/2017