| 1. |
- 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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| 2. |
- Bossi, Alessandro, et al.
(författare)
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Time domain diffuse Raman spectroscopy using single pixel detection
- 2023
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Ingår i: Biomedical Optics Express. - 2156-7085. ; 14:11, s. 5749-5763
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Tidskriftsartikel (refereegranskat)abstract
- Diffuse Raman spectroscopy (DIRS) extends the high chemical specificity of Raman scattering to in-depth investigation of thick biological tissues. We present here a novel approach for time-domain diffuse Raman spectroscopy (TD-DIRS) based on a single-pixel detector and a digital micromirror device (DMD) within an imaging spectrometer for wavelength encoding. This overcomes the intrinsic complexity and high cost of detection arrays with ps-resolving time capability. Unlike spatially offset Raman spectroscopy (SORS) or frequency offset Raman spectroscopy (FORS), TD-DIRS exploits the time-of-flight distribution of photons to probe the depth of the Raman signal at a single wavelength with a single source-detector separation. We validated the system using a bilayer tissue-bone mimicking phantom composed of a 1 cm thick slab of silicone overlaying a calcium carbonate specimen and demonstrated a high differentiation of the two Raman signals. We reconstructed the Raman spectra of the two layers, offering the potential for improved and quantitative material analysis. Using a bilayer phantom made of porcine muscle and calcium carbonate, we proved that our system can retrieve Raman peaks even in the presence of autofluorescence typical of biomedical tissues. Overall, our novel TD-DIRS setup proposes a cost-effective and high-performance approach for in-depth Raman spectroscopy in diffusive media.
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| 3. |
- Curry, Nicholas, et al.
(författare)
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Performance Testing of Suspension Plasma Sprayed Thermal Barrier Coatings Produced with Varied Suspension Parameters
- 2015
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Ingår i: Coatings. - : MDPI AG. - 2079-6412. ; 5:3, s. 338-356
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Tidskriftsartikel (refereegranskat)abstract
- Suspension plasma spraying has become an emerging technology for the production of thermal barrier coatings for the gas turbine industry. Presently, though commercial systems for coating production are available, coatings remain in the development stage. Suitable suspension parameters for coating production remain an outstanding question and the influence of suspension properties on the final coatings is not well known. For this study, a number of suspensions were produced with varied solid loadings, powder size distributions and solvents. Suspensions were sprayed onto superalloy substrates coated with high velocity air fuel (HVAF) -sprayed bond coats. Plasma spray parameters were selected to generate columnar structures based on previous experiments and were maintained at constant to discover the influence of the suspension behavior on coating microstructures. Testing of the produced thermal barrier coating (TBC) systems has included thermal cyclic fatigue testing and thermal conductivity analysis. Pore size distribution has been characterized by mercury infiltration porosimetry. Results show a strong influence of suspension viscosity and surface tension on the microstructure of the produced coatings.
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| 4. |
- Susnjar, Stefan, et al.
(författare)
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Reconstruction of Raman spectra of two-layer diffusive media: model-based approach in time-domain
- 2023
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Ingår i: Proceedings of SPIE : Diffuse Optical Spectroscopy and Imaging IX - Diffuse Optical Spectroscopy and Imaging IX. - 1996-756X .- 0277-786X. - 9781510664654 ; 12628, s. 1-126280
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Konferensbidrag (refereegranskat)abstract
- We propose a novel analytical time-domain model for migration of Raman scattered photons in inhomogeneous two-layer diffusive media. Based on this model, the methods for reconstruction of the Raman spectra of the two layers are developed, tested in simulations and validated on phantom measurements data.
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| 5. |
- Susnjar, Stefan, et al.
(författare)
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Two-layer reconstruction of Raman spectra in diffusive media based on an analytical model in the time domain
- 2023
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Ingår i: Optics Express. - 1094-4087. ; 31:24, s. 40573-40591
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Tidskriftsartikel (refereegranskat)abstract
- We derive and validate an analytical model that describes the migration of Raman scattered photons in two-layer diffusive media, based on the diffusion equation in the time domain. The model is derived under a heuristic approximation that background optical properties are identical on the excitation and Raman emission wavelengths. Methods for the reconstruction of two-layer Raman spectra have been developed, tested in computer simulations and validated on tissue-mimicking phantom measurements data. Effects of different parameters were studied in simulations, showing that the thickness of the top layer and number of detected photon counts have the most significant impact on the reconstruction. The concept of quantitative, mathematically rigorous reconstruction using the proposed model was finally proven on experimental measurements, by successfully separating the spectra of silicone and calcium carbonate (calcite) layers, showing the potential for further development and eventual application in clinical diagnostics.
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