title: Tetherless fiber-coupled optical sources for extended metronomic photodynamic therapy.
abstract: BACKGROUND
  Metronomic photodynamic therapy (mPDT) involves the delivery of a low fluence rate of light and photosensitizing drug, continuously and over an extended period. However, in mPDT trials, there has been a perceived need for light sources that can deliver light reliably for extended periods, while being small enough to be tolerated by small animals.
  
  
  METHODS
  We report on the development of tetherless, lightweight, fiber-coupled optical sources for in vivo delivery of interstitial mPDT. Two forms are reported, based on diode lasers and light-emitting diodes (LEDs), the latter types weighing only 16.5g.
  
  
  RESULTS
  The prototypes have been well tolerated in preliminary trials on tumor-bearing rat models and can currently provide stable levels of performance for upwards of 5 days. We also report an extension of the concept to units coupled to several optical fibers to enable simultaneous irradiation of multiple locations in tissue.
  
  
  CONCLUSIONS
  These prototypes fulfill a current need for reliable mPDT optical sources for use with animal models. They also serve as the foundation for the development of fiber-coupled sources for use in future clinical trials.
authors.affiliation: Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto M5G 2M9, Canada.
authors.forename: Nick
authors.initials: N
authors.lastname: Davies
authors.affiliation: Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto M5G 2M9, Canada; Ontario Cancer Institute, University Health Network, 610 University Avenue, Toronto M5G 2M9, Canada.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Wilson