PDT dosimetry instrument and system capable of measuring light fluency rate, reactive oxygen species, and photosensitizer concentration simultaneously at multiple sites and allowing to adjust the PDT dose in real-time during treatment.
Photodynamic therapy (PDT) is a treatment modality that is often used during surgeries to eradicate remaining cancer cells. PDT utilizes a drug - photosensitizer (PS) which becomes activated when exposed to a specific wavelength of light and produces reactive oxygen species (ROS) that destroys adjacent cancer cells. PDT has been approved by FDA for treatment of several types of cancers and is being tested in a number of clinical trials for treatment of brain, skin, prostate, cervix, and peritoneal cavity malignancies.
Dosing PDT is a critical aspect of the treatment - inadequate treatment dose may lead to residual cancer cells, while excessive doses may result in severe damage to the tissue leading to burns, swelling, pain, and scarring. Effective PDT dose depends on multiple factors such as local PS dose, tissue optical properties, oxygenation level, photobleaching, absorption and scattering of light, hemoglobin levels, damage to the tissue by surgery which are all dynamic. In addition, there is significant inter- and intra-patient variability in the PS pharmacokinetics, tissue optical properties, and local tissue oxygenation. Thus, there is a critical need for reliable dose metrics which would allow to deliver optimum PDT dose to treated tissues.
Dr. Timothy Zhu of Penn Medicine has developed PDT device and system which measures light fluence rate, PS concentration, and tumor blood flow. This approach allows for the calculation of local ROS concentration for accurate prediction of PDT outcome and dose adjustment. The inventor demonstrated the utility of the device in clinical settings using photofrin-mediated PDT assessing ROS levels simultaneously at multiple sites in real time.