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Tianye Niu - One of the best experts on this subject based on the ideXlab platform.
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scatter correction for a clinical cone Beam ct system using an optimized Stationary Beam blocker in a single scan
Medical Physics, 2019Co-Authors: Xiaokun Liang, Qinxuan Zhou, Zhicheng Zhang, Yangkang Jiang, Wei Zhao, Chen Luo, Jing Xiong, Xiaoming Yang, Jihong Sun, Tianye NiuAbstract:PURPOSE Scatter contamination in the cone-Beam CT (CBCT) leads to CT number inaccuracy, spatial nonuniformity, and loss of image contrast. In our previous work, we proposed a single scan scatter correction approach using a Stationary partial Beam blocker. Although the previous method works effectively on a tabletop CBCT system, it fails to achieve high image quality on a clinical CBCT system mainly due to the wobble of the LINAC gantry during scan acquisition. Due to the mechanical deformation of CBCT gantry, the wobbling effect is observed in the clinical CBCT scan, and more missing data present using the previous blocker with the uniformly distributed lead strips. METHODS An optimal blocker distribution is proposed to minimize the missing data. In the objective function of the missing data, the motion of the Beam blocker in each projection is estimated using the segmentation due to its high contrast in the blocked area. The scatter signals from the blocker are also estimated using an air scan with the inserted blocker. The final image is generated using the forward projection to compensate for the missing data. RESULTS On the Catphan©504 phantom, our approach reduces the average CT number error from 86 Hounsfield unit (HU) to 9 HU and improves the image contrast by a factor of 1.45 in the high-contrast rods. On a head patient, the CT number error is reduced from 97 HU to 6 HU in the soft-tissue region and the image spatial nonuniformity is decreased from 27% to 5%. CONCLUSIONS The results suggest that the proposed method is promising for clinical applications.
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su f j 211 scatter correction for clinical cone Beam ct system using an optimized Stationary Beam blocker with a single scan
Medical Physics, 2016Co-Authors: Xiaokun Liang, S Gong, Qinxuan Zhou, Zhicheng Zhang, Yaoqin Xie, Tianye NiuAbstract:Purpose: X-ray scatter photons result in significant image quality degradation of cone-Beam CT (CBCT). Measurement based algorithms using Beam blocker directly acquire the scatter samples and achieve significant improvement on the quality of CBCT image. Within existing algorithms, single-scan and Stationary Beam blocker proposed previously is promising due to its simplicity and practicability. Although demonstrated effectively on tabletop system, the blocker fails to estimate the scatter distribution on clinical CBCT system mainly due to the gantry wobble. In addition, the uniform distributed blocker strips in our previous design results in primary data loss in the CBCT system and leads to the image artifacts due to data insufficiency. Methods: We investigate the motion behavior of the Beam blocker in each projection and design an optimized non-uniform blocker strip distribution which accounts for the data insufficiency issue. An accurate scatter estimation is then achieved from the wobble modeling. Blocker wobble curve is estimated using threshold-based segmentation algorithms in each projection. In the blocker design optimization, the quality of final image is quantified using the number of the primary data loss voxels and the mesh adaptive direct search algorithm is applied to minimize the objective function. Scatter-corrected CT images are obtained using the optimized blocker. Results: The proposed method is evaluated using Catphan@504 phantom and a head patient. On the Catphan©504, our approach reduces the average CT number error from 115 Hounsfield unit (HU) to 11 HU in the selected regions of interest, and improves the image contrast by a factor of 1.45 in the high-contrast regions. On the head patient, the CT number error is reduced from 97 HU to 6 HU in the soft tissue region and image spatial non-uniformity is decreased from 27% to 5% after correction. Conclusion: The proposed optimized blocker design is practical and attractive for CBCT guided radiation therapy. This work is supported by grants from Guangdong Innovative Research Team Program of China (Grant No. 2011S013), National 863 Programs of China (Grant Nos. 2012AA02A604 and 2015AA043203), the National High-tech R&D Program for Young Scientists by the Ministry of Science and Technology of China (Grant No. 2015AA020917)
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low dose and scatter free cone Beam ct imaging using a Stationary Beam blocker in a single scan phantom studies
Computational and Mathematical Methods in Medicine, 2013Co-Authors: Xue Dong, Tianye Niu, Michael Petrongolo, Lei ZhuAbstract:Excessive imaging dose from repeated scans and poor image quality mainly due to scatter contamination are the two bottlenecks of cone-Beam CT (CBCT) imaging. Compressed sensing (CS) reconstruction algorithms show promises in recovering faithful signals from low-dose projection data but do not serve well the needs of accurate CBCT imaging if effective scatter correction is not in place. Scatter can be accurately measured and removed using measurement-based methods. However, these approaches are considered unpractical in the conventional FDK reconstruction, due to the inevitable primary loss for scatter measurement. We combine measurement-based scatter correction and CS-based iterative reconstruction to generate scatter-free images from low-dose projections. We distribute blocked areas on the detector where primary signals are considered redundant in a full scan. Scatter distribution is estimated by interpolating/extrapolating measured scatter samples inside blocked areas. CS-based iterative reconstruction is finally carried out on the undersampled data to obtain scatter-free and low-dose CBCT images. With only 25% of conventional full-scan dose, our method reduces the average CT number error from 250 HU to 24 HU and increases the contrast by a factor of 2.1 on Catphan 600 phantom. On an anthropomorphic head phantom, the average CT number error is reduced from 224 HU to 10 HU in the central uniform area.
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scatter correction for full fan volumetric ct using a Stationary Beam blocker in a single full scan
Medical Physics, 2011Co-Authors: Tianye Niu, Lei ZhuAbstract:Purpose: Applications of volumetric CT (VCT) are hampered by shading and streaking artifacts in the reconstructed images. These artifacts are mainly due to strong x-ray scatter signals accompanied with the large illumination area within one projection, which lead to CT number inaccuracy, image contrast loss and spatial nonuniformity. Although different scatter correction algorithms have been proposed in literature, a standard solution still remains unclear. Measurement-based methods use a Beam blocker to acquire scatter samples. These techniques have unrivaled advantages over other existing algorithms in that they are simple and efficient, and achieve high scatter estimation accuracy without prior knowledge of the imaged object. Nevertheless, primary signal loss is inevitable in the scatter measurement, and multiple scans or moving the Beam blocker during data acquisition are typically employed to compensate for the missing primary data. In this paper, we propose a new measurement-based scatter correction algorithm without primary compensation for full-fan VCT. An accurate reconstruction is obtained with one single-scan and a Stationary x-ray Beam blocker, two seemingly incompatible features which enable simple and efficient scatter correction without increase of scan time or patient dose. Methods: Based on the CT reconstruction theory, we distribute the blocked data over the projection area where primary signals are considered approximately redundant in a full scan, such that the CT image quality is not degraded even with primary loss. Scatter is then accurately estimated by interpolation and scatter-corrected CT images are obtained using an FDK-based reconstruction algorithm. Results: The proposed method is evaluated using two phantom studies on a tabletop CBCT system. On the Catphan©600 phantom, our approach reduces the reconstruction error from 207 Hounsfield unit (HU) to 9 HU in the selected region of interest, and improves the image contrast by a factor of 2.0 in the high-contrast regions. On an anthropomorphic head phantom, the reconstruction error is reduced from 97 HU to 6 HU in the soft tissue region and image spatial nonuniformity decreases from 27% to 5% after correction. Conclusions: Our method inherits the main advantages of measurement-based methods while avoiding their shortcomings. It has the potential to become a practical scatter correction solution widely implementable on different VCT systems.
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tu c 214 09 single scan scatter correction for volumetric ct using a Stationary Beam blocker phantom studies
Medical Physics, 2011Co-Authors: Tianye Niu, Lei ZhuAbstract:Purpose: Although volumetric CT (VCT) is widely used nowadays, its imaging performance is greatly hindered by the inferior image quality mainly owing to large x‐ray scatter signals, which lead to CT number inaccuracy and image contrast loss. Among existing algorithms, measurement‐based scatter correction methods efficiently obtain accurate scatter estimation without prior knowledge on the object. However, with a Beam blocker in the field to attenuate primary, it is generally believed that the acquired data in scatter measurement projections are not complete for an accurate reconstruction. Thus an extra scan or moving the blocker during the scan is typically required. In this work, we propose a new measurement‐ based scatter correction algorithm without primary compensation. An accurate reconstruction is achieved with one single scan and a Stationary x‐ ray Beam blocker, two seemingly incompatible features. Methods: The blocked areas are distributed over the projection where primary signals are redundant using a new Beam blocker with a “crossing finger” shape. Scatter is then accurately estimated by interpolation and scatter‐corrected CTimages are obtained using an FDK‐based reconstruction. Three blockers with different strip gaps are manufactured for optimal strip gap selection. Results: The proposed method is evaluated using two phantom studies on our tabletop CBCT system. On the Catphan©600 phantom, our approach reduces the reconstruction error from 207 to 9 Hounsfield unit (HU) in the selected ROI, and improves the image contrast by a factor of 2 in the high‐ contrast regions. On an anthropomorphic head phantom, the reconstruction error is reduced from 154 to 3 HU in the soft‐tissue region. A blocker with a strip gap of 20mm achieves optimal image quality. Conclusions: Our method inherits the main advantages of measurement‐based methods while avoiding their shortcomings. It has the potential to become a practical scatter correction solution widely implementable on different VCT systems.
W Kohler - One of the best experts on this subject based on the ideXlab platform.
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measurement of diffusion and thermal diffusion in ternary fluid mixtures using a two color optical Beam deflection technique
Journal of Chemical Physics, 2010Co-Authors: A Koniger, H Wunderlich, W KohlerAbstract:We have developed a highly sensitive two-color Beam deflection setup to measure diffusion and thermal diffusion in ternary fluid mixtures following a suggestion of Haugen and Firoozabadi [J. Phys. Chem. B 110, 17678 (2006)]. Simultaneous detection of two laser Beams with different wavelengths makes it possible to determine the time dependent concentration profiles of all three components. By comparing the measured Beam deflection signals to a numerical solution of the coupled heat and mass transport equations, the diffusion matrix, the thermal diffusion, and the Soret coefficients are obtained by a numerical model combined with a nonlinear least-squares fitting routine. The results can be improved by additional thermal diffusion forced Rayleigh scattering experiments, which yield a contrast-weighted average thermal diffusion coefficient. The three Soret coefficients can be obtained independently from the Stationary Beam deflection amplitudes. Measurements have been performed on the symmetric (equal weight...
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measurement of diffusion and thermal diffusion in ternary fluid mixtures using a two color optical Beam deflection technique
Journal of Chemical Physics, 2010Co-Authors: A Koniger, H Wunderlich, W KohlerAbstract:We have developed a highly sensitive two-color Beam deflection setup to measure diffusion and thermal diffusion in ternary fluid mixtures following a suggestion of Haugen and Firoozabadi [J. Phys. Chem. B 110, 17678 (2006)]. Simultaneous detection of two laser Beams with different wavelengths makes it possible to determine the time dependent concentration profiles of all three components. By comparing the measured Beam deflection signals to a numerical solution of the coupled heat and mass transport equations, the diffusion matrix, the thermal diffusion, and the Soret coefficients are obtained by a numerical model combined with a nonlinear least-squares fitting routine. The results can be improved by additional thermal diffusion forced Rayleigh scattering experiments, which yield a contrast-weighted average thermal diffusion coefficient. The three Soret coefficients can be obtained independently from the Stationary Beam deflection amplitudes. Measurements have been performed on the symmetric (equal weight fractions) ternary mixtures dodecane/isobutylbenzene/1,2,3,4-tetrahydronaphthalene and 1-methylnaphthalene/octane/decane. There is only partial agreement between our results and literature data.
C. Strazielle - One of the best experts on this subject based on the ideXlab platform.
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neurobehavioral characterization of app23 transgenic mice with the shirpa primary screen
Behavioural Brain Research, 2005Co-Authors: Robert Lalonde, M Dumont, Matthias Staufenbiel, C. StrazielleAbstract:The SHIRPA primary screen comprises 40 measures covering various reflexes and basic sensorimotor functions. This multi-test battery was used to compare non-transgenic controls with APP23 transgenic mice, expressing the 751 isoform of human beta-amyloid precursor protein and characterized by amyloid deposits in parenchyma and vessel walls. The APP23 mice were distinguishable from controls by pathological limb reflexes, myoclonic jumping, seizure activity, and tail malformation. In addition, this mouse model of Alzheimer's disease was also marked by a crooked swimming trajectory. APP23 mice were also of lighter weight and were less inclined to stay immobile during a transfer arousal test. Despite the neurologic signs, APP23 transgenic mice were not deficient in Stationary Beam, coat-hanger, and rotorod tests, indicating intact motor coordination abilities.
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characterization of hemizygous sod1 wild type transgenic mice with the shirpa primary screen and tests of sensorimotor function and anxiety
Brain Research Bulletin, 2004Co-Authors: Robert Lalonde, M Dumont, Evelyn Paly, Jacqueline London, C. StrazielleAbstract:SOD1 is one of several overexpressed genes in Down's syndrome. In order to dissect genetic causes of the syndrome, hemizygous human wild-type SOD1 transgenic mice were compared to FVB/N non-transgenic controls at 3 months of age in the SHIRPA primary screen of neurologic function as well as in tests of motor activity and coordination. The responsiveness of SOD1/wt transgenic mice to visual and somatosensory stimuli was reduced in placing, pinna, corneal, and toe-pinch tests. In addition, SOD1/wt transgenic mice crossed fewer segments on a Stationary Beam. On the contrary, there was no intergroup difference for motor activity and anxiety in open-field and emergence tests and for latencies before falling on the Stationary Beam, coat-hanger, and rotorod. These results indicate mild deficits in sensorimotor responsiveness in a mouse model expressing human SOD1 and that the overexpressed gene may be responsible for some Down symptoms.
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Characterization of NFH-LacZ transgenic mice with the SHIRPA primary screening battery and tests of motor coordination, exploratory activity, and spatial learning
Behavioural processes, 2003Co-Authors: R. Lalonde, Joël Eyer, V. Wunderle, C. StrazielleAbstract:NFH-LacZ transgenic mice express a fusion protein between a truncated form of the endogenous neurofilament of heavy molecular weight and the complete E. coli β-galactosidase. NFH-LacZ transgenic mice could be distinguished from controls in the SHIRPA neurological battery by the appearance of action tremor and hindlimb clasping and a lower body weight. Despite normal exploratory activity and spatial learning, NFH-LacZ transgenic mice were deficient in Stationary Beam, coat-hanger, and rotorod tests of motor coordination. These results are concordant with neuropathological findings in spinal motoneurons and the cerebellum and indicate that despite the absence of paralysis, these transgenic mice may serve as an experimental model of the early stage of amyotrophic lateral sclerosis.
Lei Zhu - One of the best experts on this subject based on the ideXlab platform.
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low dose and scatter free cone Beam ct imaging using a Stationary Beam blocker in a single scan phantom studies
Computational and Mathematical Methods in Medicine, 2013Co-Authors: Xue Dong, Tianye Niu, Michael Petrongolo, Lei ZhuAbstract:Excessive imaging dose from repeated scans and poor image quality mainly due to scatter contamination are the two bottlenecks of cone-Beam CT (CBCT) imaging. Compressed sensing (CS) reconstruction algorithms show promises in recovering faithful signals from low-dose projection data but do not serve well the needs of accurate CBCT imaging if effective scatter correction is not in place. Scatter can be accurately measured and removed using measurement-based methods. However, these approaches are considered unpractical in the conventional FDK reconstruction, due to the inevitable primary loss for scatter measurement. We combine measurement-based scatter correction and CS-based iterative reconstruction to generate scatter-free images from low-dose projections. We distribute blocked areas on the detector where primary signals are considered redundant in a full scan. Scatter distribution is estimated by interpolating/extrapolating measured scatter samples inside blocked areas. CS-based iterative reconstruction is finally carried out on the undersampled data to obtain scatter-free and low-dose CBCT images. With only 25% of conventional full-scan dose, our method reduces the average CT number error from 250 HU to 24 HU and increases the contrast by a factor of 2.1 on Catphan 600 phantom. On an anthropomorphic head phantom, the average CT number error is reduced from 224 HU to 10 HU in the central uniform area.
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scatter correction for full fan volumetric ct using a Stationary Beam blocker in a single full scan
Medical Physics, 2011Co-Authors: Tianye Niu, Lei ZhuAbstract:Purpose: Applications of volumetric CT (VCT) are hampered by shading and streaking artifacts in the reconstructed images. These artifacts are mainly due to strong x-ray scatter signals accompanied with the large illumination area within one projection, which lead to CT number inaccuracy, image contrast loss and spatial nonuniformity. Although different scatter correction algorithms have been proposed in literature, a standard solution still remains unclear. Measurement-based methods use a Beam blocker to acquire scatter samples. These techniques have unrivaled advantages over other existing algorithms in that they are simple and efficient, and achieve high scatter estimation accuracy without prior knowledge of the imaged object. Nevertheless, primary signal loss is inevitable in the scatter measurement, and multiple scans or moving the Beam blocker during data acquisition are typically employed to compensate for the missing primary data. In this paper, we propose a new measurement-based scatter correction algorithm without primary compensation for full-fan VCT. An accurate reconstruction is obtained with one single-scan and a Stationary x-ray Beam blocker, two seemingly incompatible features which enable simple and efficient scatter correction without increase of scan time or patient dose. Methods: Based on the CT reconstruction theory, we distribute the blocked data over the projection area where primary signals are considered approximately redundant in a full scan, such that the CT image quality is not degraded even with primary loss. Scatter is then accurately estimated by interpolation and scatter-corrected CT images are obtained using an FDK-based reconstruction algorithm. Results: The proposed method is evaluated using two phantom studies on a tabletop CBCT system. On the Catphan©600 phantom, our approach reduces the reconstruction error from 207 Hounsfield unit (HU) to 9 HU in the selected region of interest, and improves the image contrast by a factor of 2.0 in the high-contrast regions. On an anthropomorphic head phantom, the reconstruction error is reduced from 97 HU to 6 HU in the soft tissue region and image spatial nonuniformity decreases from 27% to 5% after correction. Conclusions: Our method inherits the main advantages of measurement-based methods while avoiding their shortcomings. It has the potential to become a practical scatter correction solution widely implementable on different VCT systems.
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tu c 214 09 single scan scatter correction for volumetric ct using a Stationary Beam blocker phantom studies
Medical Physics, 2011Co-Authors: Tianye Niu, Lei ZhuAbstract:Purpose: Although volumetric CT (VCT) is widely used nowadays, its imaging performance is greatly hindered by the inferior image quality mainly owing to large x‐ray scatter signals, which lead to CT number inaccuracy and image contrast loss. Among existing algorithms, measurement‐based scatter correction methods efficiently obtain accurate scatter estimation without prior knowledge on the object. However, with a Beam blocker in the field to attenuate primary, it is generally believed that the acquired data in scatter measurement projections are not complete for an accurate reconstruction. Thus an extra scan or moving the blocker during the scan is typically required. In this work, we propose a new measurement‐ based scatter correction algorithm without primary compensation. An accurate reconstruction is achieved with one single scan and a Stationary x‐ ray Beam blocker, two seemingly incompatible features. Methods: The blocked areas are distributed over the projection where primary signals are redundant using a new Beam blocker with a “crossing finger” shape. Scatter is then accurately estimated by interpolation and scatter‐corrected CTimages are obtained using an FDK‐based reconstruction. Three blockers with different strip gaps are manufactured for optimal strip gap selection. Results: The proposed method is evaluated using two phantom studies on our tabletop CBCT system. On the Catphan©600 phantom, our approach reduces the reconstruction error from 207 to 9 Hounsfield unit (HU) in the selected ROI, and improves the image contrast by a factor of 2 in the high‐ contrast regions. On an anthropomorphic head phantom, the reconstruction error is reduced from 154 to 3 HU in the soft‐tissue region. A blocker with a strip gap of 20mm achieves optimal image quality. Conclusions: Our method inherits the main advantages of measurement‐based methods while avoiding their shortcomings. It has the potential to become a practical scatter correction solution widely implementable on different VCT systems.
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single scan scatter correction for cone Beam ct using a Stationary Beam blocker a preliminary study
Proceedings of SPIE, 2011Co-Authors: Tianye Niu, Lei ZhuAbstract:The performance of cone-Beam CT (CBCT) is greatly limited by scatter artifacts. The existing measurement-based methods have promising advantages as a standard scatter correction solution, except that they currently require multiple scans or moving the Beam blocker during data acquisition to compensate for the missing primary data. These approaches are therefore unpractical in clinical applications. In this work, we propose a new measurement-based scatter correction method to achieve accurate reconstruction with one single scan and a Stationary Beam blocker, two seemingly incompatible features which enable simple and effective scatter correction without increase of scan time or patient dose. Based on CT reconstruction theory, we distribute the blocked areas over one projection where primary signals are considered to be redundant in a full scan. The CT image quality is not degraded even with primary loss. Scatter is accurately estimated by interpolation and scatter-corrected CT images are obtained using an FDK-based reconstruction. In a Monte Carlo simulation study, we first optimize the Beam blocker geometry using projections on the Shepp-Logan phantom and then carry out a complete simulation of a CBCT scan on a water phantom. With the scatter-to-primary ratio around 1.0, our method reduces the CT number error from 293 to 2.9 Hounsfield unit (HU) around the phantom center. The proposed approach is further evaluated on a CBCT tabletop system. On the Catphan©600 phantom, the reconstruction error is reduced from 202 to 10 HU in the selected region of interest after the proposed correction.
A Koniger - One of the best experts on this subject based on the ideXlab platform.
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measurement of diffusion and thermal diffusion in ternary fluid mixtures using a two color optical Beam deflection technique
Journal of Chemical Physics, 2010Co-Authors: A Koniger, H Wunderlich, W KohlerAbstract:We have developed a highly sensitive two-color Beam deflection setup to measure diffusion and thermal diffusion in ternary fluid mixtures following a suggestion of Haugen and Firoozabadi [J. Phys. Chem. B 110, 17678 (2006)]. Simultaneous detection of two laser Beams with different wavelengths makes it possible to determine the time dependent concentration profiles of all three components. By comparing the measured Beam deflection signals to a numerical solution of the coupled heat and mass transport equations, the diffusion matrix, the thermal diffusion, and the Soret coefficients are obtained by a numerical model combined with a nonlinear least-squares fitting routine. The results can be improved by additional thermal diffusion forced Rayleigh scattering experiments, which yield a contrast-weighted average thermal diffusion coefficient. The three Soret coefficients can be obtained independently from the Stationary Beam deflection amplitudes. Measurements have been performed on the symmetric (equal weight...
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measurement of diffusion and thermal diffusion in ternary fluid mixtures using a two color optical Beam deflection technique
Journal of Chemical Physics, 2010Co-Authors: A Koniger, H Wunderlich, W KohlerAbstract:We have developed a highly sensitive two-color Beam deflection setup to measure diffusion and thermal diffusion in ternary fluid mixtures following a suggestion of Haugen and Firoozabadi [J. Phys. Chem. B 110, 17678 (2006)]. Simultaneous detection of two laser Beams with different wavelengths makes it possible to determine the time dependent concentration profiles of all three components. By comparing the measured Beam deflection signals to a numerical solution of the coupled heat and mass transport equations, the diffusion matrix, the thermal diffusion, and the Soret coefficients are obtained by a numerical model combined with a nonlinear least-squares fitting routine. The results can be improved by additional thermal diffusion forced Rayleigh scattering experiments, which yield a contrast-weighted average thermal diffusion coefficient. The three Soret coefficients can be obtained independently from the Stationary Beam deflection amplitudes. Measurements have been performed on the symmetric (equal weight fractions) ternary mixtures dodecane/isobutylbenzene/1,2,3,4-tetrahydronaphthalene and 1-methylnaphthalene/octane/decane. There is only partial agreement between our results and literature data.