| 1. |
- Dam, J. S, et al.
(författare)
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Fiber optic system for in vivo real-time determination of tissue optical properties from steady-state diffuse reflectance measurements
- 2000
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Ingår i: PHOTON MIGRATION, DIFFUSE SPECTROSCOPY AND OPTICAL COHERENCE TOMOGRAPHY: IMAGING AND FUNCTIONAL ASSESSMENT. - : SPIE. - 0277-786X .- 1996-756X. - 0819438162 ; 1:31, s. 103-109
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Konferensbidrag (refereegranskat)abstract
- We present a versatile and compact fiber optic probe for real-time determination of the absorption and the reduced scattering coefficients from spatially resolved continuous wave diffuse reflectance measurements. The probe collects the diffuse reflectance at six distances in the range 0.6 - 7.8 mm at four arbitrary wavelengths, which were 660, 785, 805, and 974 nm in these experiments. The maximum sampling rate for one cycle of measurements including all four wavelengths is about 100 Hz. The absorption and the reduced scattering coefficients are extracted real-time from the probe measurements using multivariate calibration methods based on multiple polynomial regression and Newton-Raphson algorithms. The system was calibrated on a 6x7 matrix of Intralipid/ink phantoms with optical properties within typical biological ranges, e.g. at 785 nm, the ranges of the absorption and the reduced scattering coefficients, were 0 - 0.3 /cm and 6 - 16 /cm, respectively. Cross-validation tests shoved that the mean prediction error, relative to the ranges of absorption and the reduced scattering coefficients were 2.8 \% and 1.3 \%, respectively.
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| 2. |
- Andersson-Engels, Stefan, et al.
(författare)
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Deep-tissue optical imaging and photoactivation activities at biophotonics@tyndall
- 2016
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Ingår i: Frontiers in Optics, FiO 2016. - 2162-2701. - 9781943580194
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Konferensbidrag (refereegranskat)abstract
- Activities for deep tissue imaging and photoactivation will be presented. Wihin Biophotonics@Tyndall projects based on upconverting nanoparticles and ultrasound optical tomography will be pursued. Data from collaborative research will be given.
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| 3. |
- Andersson-Engels, Stefan, et al.
(författare)
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In vivo luminescence imaging and tomography using upconverting nanoparticles as contrast agents
- 2012
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Ingår i: 2012 Asia Communications and Photonics Conference. - 2162-108X. ; , s. 2-3
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Konferensbidrag (refereegranskat)abstract
- Upconverting nanoparticles have recently drawn increasingly attention as contrast agents for optical bioimaging. They enable autofluorescence-free imaging within the tissue optical window, and improved spatial resolution as compared to conventional fluorescence-based contrast agents. (C) 2012 Optical Society of America
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| 4. |
- Bengtsson, Alexander, et al.
(författare)
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Characterization and modeling of acousto-optic signal strengths in highly scattering media
- 2019
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Ingår i: Biomedical Optics Express. - 2156-7085. ; 10:11, s. 5565-5584
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Tidskriftsartikel (refereegranskat)abstract
- Ultrasound optical tomography (UOT) is an imaging technique based on the acousto-optic effect that can perform optical imaging with ultrasound resolution inside turbid media, and is thus interesting for biomedical applications, e.g. for assessing tissue blood oxygenation. In this paper, we present near background free measurements of UOT signal strengths using slow light filter signal detection. We carefully analyze each part of our experimental setup and match measured signal strengths with calculations based on diffusion theory. This agreement between experiment and theory allows us to assert the deep tissue imaging potential of similar to 5 cm for UOT of real human tissues predicted by previous theoretical studies [Biomed. Opt. Express 8, 4523 (2017)] with greater confidence, and indicate that future theoretical analysis of optimized UOT systems can be expected to be reliable. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
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| 5. |
- 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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| 6. |
- Gunther, Jacqueline, et al.
(författare)
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Deep tissue imaging with acousto-optical tomography and spectral hole burning with slow light effect : A theoretical study
- 2018
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Ingår i: Journal of Biomedical Optics. - 1083-3668. ; 23:7
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Tidskriftsartikel (refereegranskat)abstract
- Biological tissue is a highly scattering medium that prevents deep imaging of light. For medical applications, optical imaging offers a molecular sensitivity that would be beneficial for diagnosing and monitoring of diseases. Acousto-optical tomography has the molecular sensitivity of optical imaging with the resolution of ultrasound and has the potential for deep tissue imaging. Here, we present a theoretical study of a system that combines acousto-optical tomography and slow light spectral filters created using spectral hole burning methods. Using Monte Carlo simulations, a model to obtain the contrast-to-noise ratio (CNR) deep in biological tissue was developed. The simulations show a CNR > 1 for imaging depths of ∼5 cm in a reflection mode setup, as well as, imaging through ∼12 cm in transmission mode setups. These results are promising and form the basis for future experimental studies.
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| 7. |
- Gunther, Jacqueline, et al.
(författare)
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Theoretical study of combined acousto-optical tomography and slow light filters
- 2018
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Ingår i: Optical Tomography and Spectroscopy, OTS 2018. - 9781557528209 ; Part F90-OTS 2018
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Konferensbidrag (refereegranskat)abstract
- Monte Carlo simulations were used to determine the contrast-to-noise ratio of acoustooptical tomographic imaging with slow light filters versus possible imaging depth. Both reflection and transmission setups were considered. The theoretical model showed that imaging through 12 cm of breast tissue could be plausible.
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| 8. |
- Pifferi, A, et al.
(författare)
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Multi-distance optical characterization of the female breast by time-resolved diffuse spectroscopy
- 2003
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Ingår i: PHOTON MIGRATION AND DIFFUSE-LIGHT IMAGING. - : SPIE. - 1996-756X .- 0277-786X. - 0819450081 ; 5138, s. 6-11
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Konferensbidrag (refereegranskat)abstract
- Two systems for time-resolved diffuse spectroscopy were used for the optical characterization of the female breast in 4 volunteers. A first system was a compact laser diode instrument operated at 660 and 785 nm, while the second one was a broadband laboratory set-up based on mode-locked lasers tunable in the 610-1000 nm range. Measurements were obtained both in transmittance and in reflectance geometry at 5 inter-fiber distances ranging from I to 4 cm at different locations on the breast. Distinct spectral features both in absorption and in scattering were observed among the 4 volunteers, and for each subject between reflectance and transmittance measurements. These differences are correlated with the abundance of the glandular tissue and blood absorption. Upon increasing, the inter-fiber distance in reflectance, deeper tissue structures were investigated, generally resulting in higher water contribution.
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| 9. |
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| 10. |
- Svanberg, Katarina, et al.
(författare)
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Photodynamic Therapy of Nonmelanoma Malignant-tumors of the Skin Using Topical Delta-amino Levulinic Acid Sensitization and Laser Irradiation
- 1994
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Ingår i: British Journal of Dermatology. - : Oxford University Press (OUP). - 1365-2133 .- 0007-0963. ; 130:6, s. 743-751
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Tidskriftsartikel (refereegranskat)abstract
- Eighty basal cell carcinomas (BCCs) in 21 patients, 10 lesions of Bowen's disease in three patients, and four lesions of cutaneous T-cell lymphoma in two patients, were treated with photodynamic laser therapy (PDT), using topical application of the haem precursor delta-amino levulinic acid (ALA). The diagnoses were confirmed histologically prior to treatment. Fifty-five of the BCCs were superficial lesions, and 25 were nodular. Of the 80 BCCs, 39 (49%) were located on the trunk, 36 (45%) on the head and neck region, four (15%) on the leg and one on the arm. The two principal locations of the 10 Bowen's disease lesions were the leg (50%) and the trunk (40%). The T-cell lymphoma lesions were located on the shoulder and on the arm. A water-in-oil based cream containing 20% ALA was applied to the lesions, with a margin of about 10-20 mm beyond the visible tumour border, 4-6 h before the laser procedure. During this period of time the highly fluorescent and photodynamically active substance protoporphyrin IX (Pp IX) is synthesized via the haem cycle. Laser-induced fluorescence (LIF) was used for real-time monitoring of the Pp IX distribution in the tumour and in the normal surrounding skin, before and after treatment in all patients. Before laser treatment the Pp-IX distribution demonstrated by LIF showed a demarcation between tumour and normal skin of about 15:1 for BCC and Bowen's disease, and 5:1 for T-cell lymphomas. Laser light from a pulsed frequency-doubled Nd:YAG laser pumping a dye laser with light emission at 630 nn was used for the therapy. The power density in the irradiation was kept below 110 mW/cm(2), in order to avoid hyperthermal effects. A total energy of 60 J/cm(2) was delivered for 10-20 min, depending on the tumour size. A complete response rate of 100% in superficial BCCs and 64% in nodular BCCs occurred after a single laser treatment, and a response rate of 100% was achieved after one additional. treatment in the nodular BCCs. in the Bowen's disease lesions a complete response of 90% was obtained with a single treatment. Two of the four T-cell lymphomas resolved completely. The follow-up time was between 6 and 14 months.
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