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PDT dose dosimetry for Photofrin-mediated pleural photodynamic therapy (pPDT)
Yi Hong Ong1,2, Michele M Kim1,2, Jarod C Finlay1
1Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104, United States of America.
Physics in Medicine and Biology
|November 7, 2017
Summary
Accurate photodynamic therapy (PDT) dosimetry requires correcting photosensitizer fluorescence for tissue optical properties. This study developed a system to measure PDT dose, revealing significant intra- and inter-patient variations in photosensitizer concentration.
Area of Science:
- Biomedical Engineering
- Medical Physics
- Photodynamic Therapy Research
Background:
- Photosensitizer fluorescence monitoring during photodynamic therapy (PDT) offers insights into photosensitizer concentration and photobleaching.
- Accurate quantification of photosensitizer concentration is crucial for determining the Photodynamic Therapy (PDT) dose, a key dosimetry quantity.
- Variations in tissue optical properties can distort fluorescence measurements, necessitating correction for precise dosimetry.
Purpose of the Study:
- To develop and validate a dosimetry system for simultaneous acquisition of light dosimetry and photosensitizer fluorescence data during PDT.
- To establish an empirical optical property correction function for accurate in vivo photosensitizer quantification.
- To investigate the heterogeneity of photosensitizer concentration and delivered PDT dose in patients.
Main Methods:
- Development of a four-channel PDT dose dosimetry system.
- Utilized Monte Carlo simulations to determine an empirical optical property correction function.
- Experimentally determined correction function parameters using tissue-simulating phantoms for Photofrin.
- Performed in vivo measurements of photosensitizer fluorescence and PDT dose in the pleural cavity during PDT treatment.
Main Results:
- The developed system simultaneously acquired light dosimetry and photosensitizer fluorescence data.
- An empirical optical property correction function was determined for Photofrin fluorescence.
- In vivo measurements indicated negligible photobleaching of Photofrin during treatment.
- Significant intra-patient (2.9-fold) and inter-patient (8.3-fold) heterogeneities in photosensitizer concentration and delivered PDT dose were observed.
Conclusions:
- The developed dosimetry system enables accurate measurement of PDT dose by correcting for optical property variations.
- Significant heterogeneity in photosensitizer concentration and PDT dose delivery necessitates further investigation for optimized treatment planning.
- The findings highlight the importance of individualized dosimetry in pleural PDT to ensure effective treatment and minimize side effects.
