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In Silico, Combined Plasmonic Photothermal and Photodynamic Therapy in Mice. JOURNAL OF NANOTHERANOSTICS 2022. [DOI: 10.3390/jnt3010004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Plasmonic photothermal and photodynamic therapy (PPTT and PDT, respectively) are two cancer treatments that have the potential to be combined in a synergistic scheme. The aim of this study is to optimize the PPTT treatment part, in order to account for the PDT lack of coverage in the hypoxic tumor volume and in cancer areas laying in deep sites. For the needs of this study, a mouse was modeled, subjected to PDT and its necrotic area was estimated by using the MATLAB software. The same procedure was repeated for PPTT, using COMSOL Multiphysics. PPTT treatment parameters, namely laser power and irradiation time, were optimized in order to achieve the optimum therapeutic effect of the combined scheme. The PDT alone resulted in 54.8% tumor necrosis, covering the upper cancer layers. When the PPTT was also applied, the total necrosis percentage raised up to 99.3%, while all of the surrounding studied organs (skin, heart, lungs and trachea, ribs, liver and spleen) were spared. The optimized values of the PPTT parameters were 550 mW of laser power and 70 s of irradiation time. Hence, the PPTT–PDT combination shows great potential in achieving high levels of tumor necrosis while sparing the healthy tissues.
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Sheng T, Ong Y, Guo W, Zhu TC. Reactive oxygen species explicit dosimetry to predict tumor growth for benzoporphyrin derivative-mediated vascular photodynamic therapy. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:1-13. [PMID: 31912689 PMCID: PMC6952881 DOI: 10.1117/1.jbo.25.6.063805] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 12/03/2019] [Indexed: 06/10/2023]
Abstract
Photodynamic therapy (PDT) is a well-established treatment modality for cancer and other malignant diseases; however, quantities such as light fluence and PDT dose do not fully account for all of the dynamic interactions between the key components involved. In particular, fluence rate (ϕ) effects, which impact the photochemical oxygen consumption rate, are not accounted for. In this preclinical study, reacted reactive oxygen species ([ROS]rx) was investigated as a dosimetric quantity for PDT outcome. The ability of [ROS]rx to predict the cure index (CI) of tumor growth, CI = 1 - k / kctr, where k and kctr are the growth rate of tumor under PDT study and the control tumor without PDT, respectively, for benzoporphyrin derivative (BPD)-mediated PDT, was examined. Mice bearing radiation-induced fibrosarcoma (RIF) tumors were treated with different in-air fluences (Φ = 22.5 to 166.7 J / cm2) and in-air fluence rates (ϕair = 75 to 250 mW / cm2) with a BPD dose of 1 mg / kg and a drug-light interval (DLI) of 15 min. Treatment was delivered with a collimated laser beam of 1-cm-diameter at 690 nm. Explicit measurements of in-air light fluence rate, tissue oxygen concentration, and BPD concentration were used to calculate for [ROS]rx. Light fluence rate at 3-mm depth (ϕ3 mm), determined based on Monte-Carlo simulations, was used in the calculation of [ROS]rx at the base of tumor. CI was used as an endpoint for three dose metrics: light fluence, PDT dose, and [ROS]rx. PDT dose was defined as the product of the time-integral of photosensitizer concentration and ϕ3 mm. Preliminary studies show that [ROS]rx best correlates with CI and is an effective dosimetric quantity that can predict treatment outcome. The threshold dose for [ROS]rx for vascular BPD-mediated PDT using DLI of 15 min is determined to be 0.26 mM and is about 3.8 times smaller than the corresponding value for conventional BPD-mediated PDT using DLI of 3 h.
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Affiliation(s)
- Tianqi Sheng
- University of Pennsylvania, Department of Radiation Oncology, Philadelphia, Pennsylvania, United States
| | - Yihong Ong
- University of Pennsylvania, Department of Radiation Oncology, Philadelphia, Pennsylvania, United States
| | - Wensheng Guo
- University of Pennsylvania, Department of Biostatistics and Epidemiology, Philadelphia, Pennsylvania, United States
| | - Timothy C. Zhu
- University of Pennsylvania, Department of Radiation Oncology, Philadelphia, Pennsylvania, United States
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Kim MM, Ghogare AA, Greer A, Zhu TC. On the in vivo photochemical rate parameters for PDT reactive oxygen species modeling. Phys Med Biol 2017; 62:R1-R48. [PMID: 28166056 PMCID: PMC5510640 DOI: 10.1088/1361-6560/62/5/r1] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Photosensitizer photochemical parameters are crucial data in accurate dosimetry for photodynamic therapy (PDT) based on photochemical modeling. Progress has been made in the last few decades in determining the photochemical properties of commonly used photosensitizers (PS), but mostly in solution or in vitro. Recent developments allow for the estimation of some of these photochemical parameters in vivo. This review will cover the currently available in vivo photochemical properties of photosensitizers as well as the techniques for measuring those parameters. Furthermore, photochemical parameters that are independent of environmental factors or are universal for different photosensitizers will be examined. Most photosensitizers discussed in this review are of the type II (singlet oxygen) photooxidation category, although type I photosensitizers that involve other reactive oxygen species (ROS) will be discussed as well. The compilation of these parameters will be essential for ROS modeling of PDT.
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Affiliation(s)
- Michele M Kim
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, United States of America. Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, United States of America
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Penjweini R, Kim MM, Liu B, Zhu TC. Evaluation of the 2-(1-Hexyloxyethyl)-2-devinyl pyropheophorbide (HPPH) mediated photodynamic therapy by macroscopic singlet oxygen modeling. JOURNAL OF BIOPHOTONICS 2016; 9:1344-1354. [PMID: 27653233 PMCID: PMC5159301 DOI: 10.1002/jbio.201600121] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 07/12/2016] [Accepted: 08/21/2016] [Indexed: 05/02/2023]
Abstract
Photodynamic therapy (PDT) is known as a non-invasive treatment modality that is based on photochemical reactions between oxygen, photosensitizer, and a special wavelength of light. However, a dosimetric predictor for PDT outcome is still elusive because current dosimetric quantities do not account for the differences in the PDT oxygen consumption rate for different fluence rates. In this study, we evaluate several dose metrics, total fluence, photobleaching ratio, PDT dose, and mean reacted singlet oxygen (mean [1 O2 ]rx ) for predicting the PDT outcome and a clinically relevant tumor re-growth endpoint. For this reason, radiation-induced fibrosarcoma (RIF) mice tumors are treated with 2-(1-Hexyloxyethyl)-2-devinyl pyropheophorbide (HPPH) and different in-air fluences (30 J/cm2 , 50 J/cm2 , 135 J/cm2 , 250 J/cm2 , and 350 J/cm2 ) and in-air fluence rates (20, 50, 75, 150 mW/cm2 ). Explicit measurements of HPPH and oxygen concentration as well as tissue optical properties are performed pre- and post-treatment. Then, this information is incorporated into a macroscopic model to calculate the photobleaching, PDT dose, and mean [1 O2 ]rx . Changes in tumor volume are tracked following the treatment and compared with the dose metrics. The correlation demonstrates that mean [1 O2 ]rx serves as a better dosimetric quantity for predicting treatment outcome and a clinically relevant tumor re-growth endpoint.
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Affiliation(s)
| | | | - Baochang Liu
- University of Pennsylvania, School of Medicine, Department of Radiation Oncology, 3400 Civic Center Boulevard TRC 4W, hiladelphia, Pennsylvania 19104, USA
| | - Timothy C. Zhu
- University of Pennsylvania, School of Medicine, Department of Radiation Oncology, 3400 Civic Center Boulevard TRC 4W, hiladelphia, Pennsylvania 19104, USA
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Qiu H, Kim MM, Penjweini R, Zhu TC. Macroscopic singlet oxygen modeling for dosimetry of Photofrin-mediated photodynamic therapy: an in-vivo study. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:88002. [PMID: 27552311 PMCID: PMC5331118 DOI: 10.1117/1.jbo.21.8.088002] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 08/01/2016] [Indexed: 05/19/2023]
Abstract
Although photodynamic therapy (PDT) is an established modality for cancer treatment, current dosimetric quantities, such as light fluence and PDT dose, do not account for the differences in PDT oxygen consumption for different fluence rates ( ? ). A macroscopic model was adopted to evaluate using calculated reacted singlet oxygen concentration ( [ O 2 1 ] rx ) to predict Photofrin-PDT outcome in mice bearing radiation-induced fibrosarcoma tumors, as singlet oxygen is the primary cytotoxic species responsible for cell death in type II PDT. Using a combination of fluences (50, 135, 200, and 250 ?? J / cm 2 ) and ? (50, 75, and 150 ?? mW / cm 2 ), tumor regrowth rate, k , was determined for each condition. A tumor cure index, CI = 1 ? k / k control , was calculated based on the k between PDT-treated groups and that of the control, Available on the SPIE Digital Library.
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Affiliation(s)
- Haixia Qiu
- Chinese PLA General Hospital, Department of Laser Medicine, No. 28 Fuxing Road, Haidian District, Beijing 100853, China
- University of Pennsylvania, School of Medicine, Department of Radiation Oncology, 3400 Civic Center Boulevard TRC 4W, Philadelphia, Pennsylvania 19104, United States
| | - Michele M. Kim
- University of Pennsylvania, School of Medicine, Department of Radiation Oncology, 3400 Civic Center Boulevard TRC 4W, Philadelphia, Pennsylvania 19104, United States
- University of Pennsylvania, Department of Physics and Astronomy, 209 South 33rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Rozhin Penjweini
- University of Pennsylvania, School of Medicine, Department of Radiation Oncology, 3400 Civic Center Boulevard TRC 4W, Philadelphia, Pennsylvania 19104, United States
| | - Timothy C. Zhu
- University of Pennsylvania, School of Medicine, Department of Radiation Oncology, 3400 Civic Center Boulevard TRC 4W, Philadelphia, Pennsylvania 19104, United States
- Address all correspondence to: Timothy C. Zhu, E-mail:
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Lopez N, Mulet R, Rodríguez R. Tumor reactive ringlet oxygen approach for Monte Carlo modeling of photodynamic therapy dosimetry. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2016; 160:383-91. [PMID: 27197059 DOI: 10.1016/j.jphotobiol.2016.04.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 04/01/2016] [Accepted: 04/03/2016] [Indexed: 01/26/2023]
Abstract
Photodynamic therapy (PDT) is an emergent technique used for the treatment of several diseases. It requires the interaction of three components: a photosensitizer, a light source and tissue oxygen. Knowledge of the biophysical aspects of PDT is important for improving dosimetry protocols and treatment planning. In this paper we propose a model to simulate the spatial and temporal distribution of ground state oxygen ((3)O2), cumulative singlet excited state oxygen ((1)O2)rx and photosensitizer, in this case protoporphyrin IX (PpIX) in an ALA mediated PDT treatment. The results are analyzed in order to improve the treatment dosimetry. We compute the light fluence in the tissue using Monte Carlo simulations running in a GPU system. The concentration of (3)O2, ((1)O2)rx and the photosensitizer are calculated using this light fluence and a set of differential equations describing the photochemical reactions involved in PDT. In the model the initial photosensitizer concentration depends on tissue depth and type, moreover we consider blood vessel damage and its effect in the ground state oxygen concentration in the tissue. We introduce the tumor reactive single oxygen (TRSO) as a new dosimetry metric. It represents the amount of singlet oxygen per tumor volume that reacts, during the treatment, with the molecules in the tumor. This quantity integrates the effect of the light irradiance, the optical properties of the tumor and the normal tissue, the oxygen consumption and supply, and the photosensitizer biodistribution on the skin.
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Affiliation(s)
- N Lopez
- Group of Complex Systems and Statistical Physics, Department of General Physics, Physics Faculty, University of Havana, La Habana CP 10400, Cuba.
| | - R Mulet
- Group of Complex Systems and Statistical Physics, Department of Theoretical Physics, Physics Faculty, University of Havana, La Habana CP 10400, Cuba.
| | - R Rodríguez
- Department of Computational Medicine, National Institute of Nephrology. La Habana CP 10600, Cuba; Department of General Physics, Physics Faculty, University of Havana, La Habana CP 10400, Cuba.
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Zhu TC, Lu A, Ong YH. An improved analytic function for predicting light fluence rate in circular fields on a semi-infinite geometry. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2016; 9706:97061D. [PMID: 27053827 DOI: 10.1117/12.2213052] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Accurate determination of in-vivo light fluence rate is critical for preclinical and clinical studies involving photodynamic therapy (PDT). This study compares the longitudinal light fluence distribution inside biological tissue in the central axis of a 1 cm diameter circular uniform light field for a range of in-vivo tissue optical properties (absorption coefficients (μa) between 0.01 and 1 cm-1 and reduced scattering coefficients (μs') between 2 and 40 cm-1). This was done using Monte-Carlo simulations for a semi-infinite turbid medium in an air-tissue interface. The end goal is to develop an analytical expression that would fit the results from the Monte Carlo simulation for both the 1 cm diameter circular beam and the broad beam. Each of these parameters is expressed as a function of tissue optical properties. These results can then be compared against the existing expressions in the literature for broad beam for analysis in both accuracy and applicable range. Using the 6-parameter model, the range and accuracy for light transport through biological tissue is improved and may be used in the future as a guide in PDT for light fluence distribution for known tissue optical properties.
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Affiliation(s)
- Timothy C Zhu
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA
| | - Amy Lu
- The Warton School, University of Pennsylvania, Philadelphia, PA, USA
| | - Yi-Hong Ong
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA
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Qiu H, Kim MM, Penjweini R, Zhu TC. Dosimetry study of PHOTOFRIN-mediated photodynamic therapy in a mouse tumor model. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2016; 9694. [PMID: 27053822 DOI: 10.1117/12.2211169] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
It is well known in photodynamic therapy (PDT) that there is a large variability between PDT light dose and therapeutic outcomes. An explicit dosimetry model using apparent reacted 1O2 concentration ([1O2]rx) has been developed as a PDT dosimetric quantity to improve the accuracy of the predicted ability of therapeutic efficacy. In this study, this explicit macroscopic singlet oxygen model was adopted to establish the correlation between calculated reacted [1O2]rx and the tumor growth using Photofrin-mediated PDT in a mouse tumor model. Mice with radiation-induced fibrosarcoma (RIF) tumors were injected with Photofrin at a dose of 5 mg/kg. PDT was performed 24h later with different fluence rates (50, 75 and 150 mW/cm2) and different fluences (50 and 135 J/cm2) using a collimated light applicator coupled to a 630nm laser. The tumor volume was monitored daily after PDT and correlated with the total light fluence and [1O2]rx. Photophysical parameters as well as the singlet oxygen threshold dose for this sensitizer and the RIF tumor model were determined previously. The result showed that tumor growth rate varied greatly with light fluence for different fluence rates while [1O2]rx had a good correlation with the PDT-induced tumor growth rate. This preliminary study indicated that [1O2]rx could serve as a better dosimetric predictor for predicting PDT outcome than PDT light dose.
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Affiliation(s)
- Haixia Qiu
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104; Department of Laser Medicine, Chinese PLA General Hospital, Beijing, 100853
| | - Michele M Kim
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104; Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104
| | - Rozhin Penjweini
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104
| | - Timothy C Zhu
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104
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Penjweini R, Kim MM, Finlay JC, Zhu TC. Investigating the impact of oxygen concentration and blood flow variation on photodynamic therapy. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2016; 9694:96940L. [PMID: 27453622 PMCID: PMC4955668 DOI: 10.1117/12.2211120] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
Type II photodynamic therapy (PDT) is used for cancer treatment based on the combined action of a photosensitizer, a special wavelength of light, oxygen (3O2) and generation of singlet oxygen (1O2). Intra-patient and inter-patient variability of oxygen concentration ([3O2]) before and after the treatment as well as photosensitizer concentration and hemodynamic parameters such as blood flow during PDT has been reported. Simulation of these variations is valuable, as it would be a means for the rapid assessment of treatment effect. A mathematical model has been previously developed to incorporate the diffusion equation for light transport in tissue and the macroscopic kinetic equations for simulation of [3O2], photosensitizers in ground and triplet states and concentration of the reacted singlet oxygen ([1O2]rx) during PDT. In this study, the finite-element based calculation of the macroscopic kinetic equations is done for 2-(1-Hexyloxyethyl)-2-devinyl pyropheophorbide (HPPH)-mediated PDT by incorporating the information of the photosensitizer photochemical parameters as well as the tissue optical properties, photosensitizer concentration, initial oxygen concentration ([3O2]0), blood flow changes and ϕ that have been measured in mice bearing radiation-induced fibrosarcoma (RIF) tumors. Then, [1O2]rx calculated by using the measured [3O2] during the PDT is compared with [1O2]rx calculated based on the simulated [3O2]; both calculations showed a reasonably good agreement. Moreover, the impacts of the blood flow changes and [3O2]0 on [1O2]rx have been investigated, which showed no pronounced effect of the blood flow changes on the long-term 1O2 generation. When [3O2]0 becomes limiting, small changes in [3O2] have large effects on [1O2]rx.
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Affiliation(s)
- Rozhin Penjweini
- Department of Radiation Oncology, School of Medicine,
University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Michele M. Kim
- Department of Radiation Oncology, School of Medicine,
University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Physics and Astronomy, University of
Pennsylvania, Philadelphia, PA 19104, USA
| | - Jarod C. Finlay
- Department of Radiation Oncology, School of Medicine,
University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Timothy C. Zhu
- Department of Radiation Oncology, School of Medicine,
University of Pennsylvania, Philadelphia, PA 19104, USA
- ; phone 215-662-4043
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Kim MM, Penjweini R, Gemmell NR, Veilleux I, McCarthy A, Buller G, Hadfield RH, Wilson BC, Zhu TC. A feasibility study of singlet oxygen explicit dosmietry (SOED) of PDT by intercomparison with a singlet oxygen luminescence dosimetry (SOLD) system. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2016; 9694:969406. [PMID: 27064489 PMCID: PMC4823004 DOI: 10.1117/12.2213236] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
An explicit dosimetry model has been developed to calculate the apparent reacted 1O2 concentration ([1O2]rx) in an in-vivo model. In the model, a macroscopic quantity, g, is introduced to account for oxygen perfusion to the medium during PDT. In this study, the SOED model is extended for PDT treatment in phantom conditions where vasculature is not present; the oxygen perfusion is achieved through the air-phantom interface instead. The solution of the SOED model is obtained by solving the coupled photochemical rate equations incorporating oxygen perfusion through the air-liquid interface. Experiments were performed for two photosensitizers (PS), Rose Bengal (RB) and Photofrin (PH), in solution, using SOED and SOLD measurements to determine both the instantaneous [1O2] as well as cumulative [1O2]rx concentrations, where [1O2] rx = (1/τΔ) · ∫[1O2]dt. The PS concentrations varied between 10 and 100 mM for RB and ~200 mM for Photofrin. The resulting magnitudes of [1O2] were compared between SOED and SOLD.
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Affiliation(s)
- Michele M. Kim
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, USA
| | - Rozhin Penjweini
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA
| | - Nathan R. Gemmell
- Department of Electronic and Nanoscale Engineering, University of Glasgow, UK
| | - Israel Veilleux
- Princess Margaret Cancer Centre, University of Toronto, Canada
| | - Aongus McCarthy
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, UK
| | - Gerald Buller
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, UK
| | - Robert H. Hadfield
- Department of Electronic and Nanoscale Engineering, University of Glasgow, UK
| | - Brian C. Wilson
- Princess Margaret Cancer Centre, University of Toronto, Canada
| | - Timothy C. Zhu
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA
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Kim MM, Penjweini R, Finlay JC, Zhu TC. Determination of the low concentration correction in the macroscopic singlet oxygen model for PDT. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2015; 9694:96940D. [PMID: 27053824 PMCID: PMC4819237 DOI: 10.1117/12.2213417] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The macroscopic singlet oxygen model has been used for singlet oxygen explicit dosimetry in photodynamic therapy (PDT). The photophysical parameters for commonly used sensitizers, HPPH and BPD, have been investigated in pre-clinical studies using mouse models. So far, studies have involved optimizing fitting algorithms to obtain the some of the photophysical parameters (ξ, σ, g) and the threshold singlet oxygen dose ([1O2]rx,sh), while other parameters such as the low concentration correction, δ, has been kept as a constant. In this study, using photobleaching measurements of mice in vivo, the value of δ was also optimized and fit to better describe experimental data. Furthermore, the value of the specific photobleaching ratio (σ) was also fine-tuned using the photobleaching results. Based on literature values of δ, σ for photosensitizers can be uniquely determined using the additional photobleaching measurements. This routine will further improve the macroscopic model of singlet oxygen production for use in explicit dosimetry.
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Affiliation(s)
- Michele M Kim
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA; Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, USA
| | - Rozhin Penjweini
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA
| | - Jarod C Finlay
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA
| | - Timothy C Zhu
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA
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