| 1. |
- Axelsson, Johan, et al.
(författare)
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In vivo photosensitizer tomography inside the human prostate
- 2009
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Ingår i: Optics Letters. - 0146-9592. ; 34:3, s. 232-234
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Tidskriftsartikel (refereegranskat)abstract
- Interstitial photodynamic therapy (IPDT) provides a promising means to treat large cancerous tumors and solid organs inside the human body. The treatment outcome is dependent on the distributions of light, photosensitizer, and tissue oxygenation. We present a scheme for reconstructing the spatial distribution of a fluorescent photosensitizer. The reconstruction is based on measurements performed in the human prostate, acquired during an ongoing IPDT clinical trial, as well as in optical phantoms. We show that in an experimental setup we can quantitatively reconstruct a fluorescent inclusion in a fluorescent background. We also show reconstructions from a patient showing a heterogeneous distribution of the photosensitizer mTHPC in the human prostate. (C) 2009 Optical Society of America
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| 2. |
- Enejder, Annika, 1969, et al.
(författare)
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Influence of cell shape and aggregate formation on the optical properties of flowing whole blood
- 2003
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Ingår i: Applied Optics. - : The Optical Society. - 2155-3165 .- 0003-6935 .- 1539-4522. ; 42:7, s. 1384-1394
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Tidskriftsartikel (refereegranskat)abstract
- We studied the influence of shape and secondary, or intercellular, organization on the absorption and scattering properties of red blood cells to determine whether these properties are of any practical significance for optical evaluation of whole blood and its constituents. A series of measurements of transmittance and reflectance of light from bovine blood in a flow cuvette was conducted with a 650-900-nm integrating sphere at shear rates of 0-1600 s(-1), from which the influence of cell orientation, elongation, and aggregate formation on the absorption (mu(a)) and the reduced scattering coefficients could be quantified. Aggregation was accompanied by a decrease of 4% in mu(s)' compared with the value in randomly oriented single cells. Increasing the degree of cell alignment and elongation as a result of increasing shear rate reduced mu(s)' by 6% and mu(a) by 3%, evaluated at a shear rate of 1600 s(-1). Comparison with T-matrix computations for oblate- and prolate-shaped cells with corresponding elongation and orientation indicates that the optical properties of whole blood are determined by those of its individual cells, though influenced by a collective scattering factor that depends on the cell-to-cell organization. We demonstrate that cell morphological changes must be taken into consideration when one is conducting whole blood spectroscopy. (C) 2003 Optical Society of America.
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| 3. |
- Ghauri, Muhammad Daniyal, et al.
(författare)
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Hybrid heterogeneous phantoms for biomedical applications: a demonstration to dosimetry validation
- 2024
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Ingår i: Biomedical Optics Express. - 2156-7085. ; 15:2, s. 863-874
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Tidskriftsartikel (refereegranskat)abstract
- Phantoms simultaneously mimicking anatomical and optical properties of real tissues can play a pivotal role for improving dosimetry algorithms. The aim of the paper is to design and develop a hybrid phantom model that builds up on the strengths of solid and liquid phantoms for mimicking various anatomical structures for prostate cancer photodynamic therapy (PDT) dosimetry validation. The model comprises of a photosensitizer-embedded gelatin lesion within a liquid Intralipid prostate shape that is surrounded by a solid silicone outer shell. The hybrid phantom was well characterized for optical properties. The final assembled phantom was also evaluated for fluorescence tomographic reconstruction in conjunction with SpectraCure’s IDOSE software. The developed model can lead to advancements in dosimetric evaluations. This would improve PDT outlook as a clinical treatment modality and boost phantom based standardization of biophotonic devices globally.
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| 4. |
- He, Jiangping, et al.
(författare)
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Light scattering by multiple red blood cells
- 2004
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Ingår i: Journal of the Optical Society of America A: Optics and Image Science, and Vision. - 1084-7529. ; 21:10, s. 1953-1961
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Tidskriftsartikel (refereegranskat)abstract
- The interaction of light with multiple red blood cells was systematically investigated by the finite-difference time-domain method (FDTD). The simulations showed that the lateral multiple scattering between red blood cells is very weak and that the polarization has an almost insignificant influence on the distribution of the scattered light. The numerical results of the FDTD method were compared with the results from the Rytov approximation and the discrete dipole approximation (DDA). The agreement with the DDA was excellent.
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| 5. |
- He, Jiangping, et al.
(författare)
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Light Scattering By Multiple Red Blood Cells
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The interaction of light with multiple red blood cells was systematically investigated by the finite-different time-domain method. The simulations show that the lateral multiple scattering between red blood cells is very weak. The polarization is shown to have an almost insignificant influence on the distribution of the scattered light. The numerical results were compared with three approximate methods: the superposition approximation, the Rytov approximation and the discrete dipole approximation. The agreement was very good.
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| 6. |
- Höglund, Odd, et al.
(författare)
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Online dosimetry for temoporfin-mediated interstitial photodynamic therapy using the canine prostate as model
- 2016
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Ingår i: Journal of Biomedical Optics. - 1083-3668 .- 1560-2281. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- Online light dosimetry with real-time feedback was applied for temoporfin-mediated interstitial photodynamic therapy (PDT) of dog prostate. The aim was to investigate the performance of online dosimetry by studying the correlation between light dose plans and the tissue response, i.e., extent of induced tissue necrosis and damage to surrounding organs at risk. Light-dose planning software provided dose plans, including light source positions and light doses, based on ultrasound images. A laser instrument provided therapeutic light and dosimetric measurements. The procedure was designed to closely emulate the procedure for whole-prostate PDT in humans with prostate cancer. Nine healthy dogs were subjected to the procedure according to a light-dose escalation plan. About 0.15 mg/kg temoporfin was administered 72 h before the procedure. The results of the procedure were assessed by magnetic resonance imaging, and gross pathology and histopathology of excised tissue. Light dose planning and online dosimetry clearly resulted in more focused effect and less damage to surrounding tissue than interstitial PDT without dosimetry. A light energy dose-response relationship was established where the threshold dose to induce prostate gland necrosis was estimated from 20 to 30 J/cm(2). (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)
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| 7. |
- Johansson, Ann, et al.
(författare)
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Interstitial photodynamic therapy for primary prostate cancer incorporating realtime treatment dosimetry
- 2007
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1042-4687 .- 1605-7422. ; 6427, s. 4270-4270
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Konferensbidrag (refereegranskat)abstract
- Photodynamic therapy (PDT) for the treatment of prostate cancer has been demonstrated to be a safe treatment option capable of inducing tissue necrosis and decrease in prostate specific antigen (PSA). Research groups report on large variations in treatment response, possibly due to biological variations in tissue composition and shortterm response to the therapeutic irradiation. Within our group, an instrument for interstitial PDT on prostate tissue that incorporates realtime treatment feedback is being developed. The treatment protocol consists of two parts. The first part incorporates the pre-treatment plan with ultrasound investigations, providing the geometry for the prostate gland and surrounding risk organs, an iterative random-search algorithm to determine near-optimal fiber positions within the reconstructed geometry and a Block-Cimmino optimization algorithm for predicting individual fiber irradiation times. During the second part, the therapeutic light delivery is combined with measurements of the light transmission signals between the optical fibers, thus monitoring the tissue effective attenuation coefficient by means of spatially resolved spectroscopy. These data are then used as input for repeated runs of the Block-Cimmino optimization algorithm. Thus, the irradiation times for individual fibers are updated throughout the treatment in order to compensate for the influence of changes in tissue composition on the light distribution at the therapeutic wavelength.
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| 8. |
- Johansson, Ann, et al.
(författare)
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Realtime light dosimetry software tools for interstitial photodynamic therapy of the human prostate
- 2007
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Ingår i: Medical Physics. - : Wiley. - 0094-2405. ; 34:11, s. 4309-4321
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Tidskriftsartikel (refereegranskat)abstract
- Photodynamic therapy (PDT) for the treatment of prostate cancer has been demonstrated to be a safe treatment option capable of inducing tissue destruction and decreasing prostate specific antigen (PSA) levels. However, prostate-PDT results in large intra- and interpatient variations in treatment response, possibly due to biological variations in tissue composition and short-term response to the therapeutic irradiation. Within our group, an instrument for interstitial PDT on prostate tissue has been developed that combines therapeutic light delivery and monitoring of light transmission via numerous bare-ended optical fibers. Here, we present algorithms that utilize data on the light distribution within the target tissue to provide realtime treatment feedback based on a light dose threshold model for PDT. This realtime dosimetry module is implemented to individualize the light dose and compensate for any treatment-induced variations in light attenuation. More specifically, based on the light transmission signals between treatment fibers, spatially resolved spectroscopy is utilized to assess the effective attenuation coefficient of the tissue. These data constitute input to a block-Cimmino optimization algorithm, employed to calculate individual fiber irradiation times provided the requirement to deliver a predetermined light dose to the target tissue while sparing surrounding sensitive organs. By repeatedly monitoring the light transmission signals during the entire treatment session, optical properties and individual fiber irradiation times are updated in realtime. The functionality of the algorithms is tested on diffuse light distribution data simulated by means of the finite element method (FEM). The feasibility of utilizing spatially resolved spectroscopy within heterogeneous media such as the prostate gland is discussed. Furthermore, we demonstrate the ability of the block-Cimmino algorithm to discriminate between target tissue and organs at risk (OAR). Finally, the realtime dosimetry module is evaluated for treatment scenarios displaying spatially and temporally varying light attenuation levels within the target tissue. We conclude that the realtime dosimetry module makes it possible to deliver a certain light dose to the target tissue despite spatial and temporal variations of the target tissue optical properties at the therapeutic wavelength.
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| 9. |
- Karlsson, Anders, et al.
(författare)
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Numerical simulations of light scattering by red blood cells
- 2005
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Ingår i: IEEE Transactions on Biomedical Engineering. - 0018-9294 .- 1558-2531. ; 52:1, s. 13-18
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Tidskriftsartikel (refereegranskat)abstract
- Scattering of electromagnetic waves from a red blood cell is simulated using the finite-difference time-domain method (FDTD), the Rytov approximation and the discrete dipole approximation (DDA). Both FDTD and DDA are fall wave methods that give accurate results in a wide range of wavelengths. The Rytov approximation is a much simpler method that is limited to scattering angles within 30° from the forward direction. The investigation comprehends different wavelengths and different orientations of the cell. It shows that the shape, volume, and orientation of the cell have a large inflaence on the forward scattering.
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| 10. |
- Karlsson, Anders, et al.
(författare)
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Numerical simulations of light scattering by red blood cells
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The electromagnetic scattering properties of red blood cells were analyzed by three different methods. The finite-different time-domain method is a general and flexible approach and enables accurate simulations of scattering from objects with arbitrary shape. This method was compared with two approximate methods: the Rytov approximation and the Discrete Dipole Approximation. The interaction of light with a red blood cell was systematically investigated using different wavelengths and orientations of the cells. The simulations show that the cell shape, as well as the cell volume and orientation, have a large influence on the forward scattering.
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