Ultra low fluence rate photodynamic therapy: Simulation of light emitted by the Cerenkov effect

Jonathan Gonzales, Fred Wang, Genesis Zamora, Anthony Trinidad, Laura Marcu, Simon R Cherry, Henry Hirschberg

Research output: Chapter in Book/Report/Conference proceedingConference contribution

11 Scopus citations


PDT has been shown to be most effective at low fluence rates. Many radionuclides used for both diagnostic and therapeutic purposes produce measurable amounts of visible radiation when they decay via the Cerenkov effect which occurs when a charged particle travels faster in a dielectric medium than the speed of light in that medium. Cerenkov radiation from radiopharmaceuticals could serve as a source of extended duration, low level "internalâ " light, to mediate PDT, with the ultimate goals of overcoming some its current limitations. Using laser light, we are exploring the effects of fluence rates that could be generated by Cerenkov radiation on PDT efficacy. ALA or TPPS2a mediated PDT of rat gliomas monolayers or multicell spheroids (F98, C6) was performed with 410 nm laser light exposure over an extended period of 24-96hrs. Photosensitizers were delivered either as a bolus or continuously with light exposure. At fluence rate of 20μW/cm2 effective PDT was obtained as measured by decrease in cell viability or inhibition of spheroid growth. PDT is effective at ultra low fluence rates if given over long time periods. No lower threshold has been ascertained. Since the half-life of 90Y, a radionuclide with a high Cherenkov yield is 64 hrs it is a good candidate to supply sufficient light activation for PDT. The combination of radionuclide and photodynamic therapies could improve the effectiveness of cancer treatment by exploiting synergies between these two modalities.

Original languageEnglish (US)
Title of host publicationProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISBN (Print)9780819498410
StatePublished - 2014
EventOptical Techniques in Neurosurgery, Neurophotonics, and Optogenetics - San Francisco, CA, United States
Duration: Feb 1 2014Feb 4 2014


OtherOptical Techniques in Neurosurgery, Neurophotonics, and Optogenetics
Country/TerritoryUnited States
CitySan Francisco, CA

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Radiology Nuclear Medicine and imaging


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