Photodynamic therapy dosimetry using multiexcitation multiemission wavelength: toward real-time prediction of treatment outcome

Monirehalsadat Mousavi, Lilian Tan Moriyama, Clovis Grecco, Marcelo Saito Nogueira, Katarina Svanberg, Cristina Kurachi, Stefan Andersson-Engels

Research output: Contribution to journalArticlepeer-review

Abstract

Evaluating the optical properties of biological tissues is needed to achieve accurate dosimetry during photodynamic therapy (PDT). Currently, accurate assessment of the photosensitizer (PS) concentration by fluorescence measurements during PDT is typically hindered by the lack of information about tissue optical properties. In the present work, a hand-held fiber-optic probe instrument monitoring fluorescence and reflectance is used for assessing blood volume, reduced scattering coefficient, and PS concentration facilitating accurate dosimetry for PDT. System validation was carried out on tissue phantoms using nonlinear least squares support machine regression analysis. It showed a high correlation coefficient (>0.99) in the prediction of the PS concentration upon a large variety of phantom optical properties. In vivo measurements were conducted in a PDT chlorine e6 dose escalating trial involving 36 male Swiss mice with Ehrlich solid tumors in which fluences of 5, 15, and 40  J cm  -  2 were delivered at two fluence rates (100 and 40  mW cm  -  2). Remarkably, quantitative measurement of fluorophore concentration was achieved in the in vivo experiment. Diffuse reflectance spectroscopy (DRS) system was also used to independently measure the physiological properties of the target tissues for result comparisons. Then, blood volume and scattering coefficient measured by the fiber-optic probe system were compared with the corresponding result measured by DRS and showed agreement. Additionally, tumor hemoglobin oxygen saturation was measured using the DRS system. Overall, the system is capable of assessing the implicit photodynamic dose to predict the PDT outcome.

Original languageEnglish
Pages (from-to)1-14
Number of pages14
JournalJournal of Biomedical Optics
Volume25
Issue number6
DOIs
Publication statusPublished - 2020

Subject classification (UKÄ)

  • Medical Laboratory and Measurements Technologies
  • Bioengineering Equipment
  • Atom and Molecular Physics and Optics

Keywords

  • biomedical optics
  • dosimetry
  • fiber-optic probe
  • fluorescence
  • in vivo measurement
  • optical properties
  • photodynamic therapy

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