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FP7 FMTXCT Project UMCE-HGUGM first year activity report Partner FIHGM Laboratorio de Imagen Médica. Medicina Experimental Hospital Universitario Gregorio Marañón, Madrid
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Workpackage 2: XCT development Workpackage 8: FMT-XCT imaging accuracy versus PET-XCT
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Workpackage 2: XCT development Use of X-ray contrast agents Double exposure techniques Dual energy X-ray source
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CT System Outline Mechanical Design
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Multi-Energy data acquisition/processing New Tube Features Voltage setting range40 to 110 kV Current setting range10 to 800 μA Output windowBeryllium (thickness 500 μm) Focal spot size15 μm (6 W) – 80 μm (50 W) Emission angle62 deg (max) Power50 W
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CT System Outline Linear stage to change magnification factor and FOV Filter wheel to change X-ray beam properties X-ray shutter Continuous and step and shoot acquistion protocols Acquisition SW with online raw data processing GPU implementation to increase processing speed allowing the use of faster detectors
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Detector Dynamic Range Expansion Dual-Exposure technique Main features Two datasets acquired First Low SNR for dense materials Detector not saturated for soft materials Second High SNR for dense materials Detector saturated for soft materials Same X-ray beam spectral properties Different photon flux
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Detector Dynamic Range Expansion Dual-Exposure technique Dataset #1Dataset #2
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Detector Dynamic Range Expansion Dual-Exposure technique (work in progress) Dual exposure CNR (PTFE/Air) = 22.11 Single exposure CNR (PTFE/Air) = 13.91
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Mean Energy = 55.6 kVMean Energy = 66.1 kV Multi-Energy data acquisition/processing Simulated Spectra for the new tube Changing filter setting Spectral simulations carried out using SPEKTR software libraries Siewerdsen, et.al., “Spektr: A computational tool for x-ray spectral analysis and imaging system optimization”, Med. Phys.31(9), 2004
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Mean Energy = 34.9 kVMean Energy = 66.1 kV Multi-Energy data acquisition/processing Simulated Spectra for the new tube Changing X-ray tube setting
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Fenestra Iopamiro Use of X-ray contrast agents
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Mouse 200 µA, voltage 50 kV 200 µm Fenestra LC Mouse 200 µA, voltage 50 kV 200 µm Iopamiro
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Mouse 200 µA, voltage 50 kV 200 µm Iopamiro Dynamic study
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Workpackage 8: FMT-XCT imaging accuracy versus PET-XCT
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Materials selection for the optical phantom construction Water Gelatin Silicon Ti02 Pro Jet Polyester resin India ink Lipid emulsions (Intralipid) Polymer microspheres Bulk materialsScatterersAbsorbers ++
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Things to have in mind when designing a FMT phantom. Resolution is depth dependent Diffusion approximation: One photon mean free path ≈ 1mm Source Detector Source
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Things to have in mind when designing a FMT phantom. Heterogeneities, surface
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Phantom design Heterogeneities 4 mm Fluorescent spheres, 2 mm (Should their size vary?)
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FMT-XCT
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How to insert the fluorophore in the phantom? Resin vs Silicon - Mix the fluorophore with the bulk material* - Capillaries (diffusive-non diffusive interfaces) - Pellets * John Baeten et al “Development of fluorescent materials for Diffuse Fluorescence Tomography standars and phantoms” Optics express vol 15 2007
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What to measure Resolution. FWHM of point-like source? Quantification accuracy Sensitivity: In-vivo specific application PET phantom remarks
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Will the imaging performance hold in the “many body imaging situation”?
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PET phantom
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Detector Dynamic Range Expansion Dual-Exposure technique Main features X-ray tube current calculation for the second scan Based on Histogran processing Shift the histogram to place 75% of the total value into the High-Gain region Dataset combination Detector Model Image combination based on a Maximum-Likelihood calculation assuming Independent Gaussian distribution. - i : Acquisition number - j : Pixel number - A: Current value - N: Noise value
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FMT system
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Resultados preliminares, maniquíes: Agar based, TiO2 (scatter), Blank ink (absorption) coronal Z=0.25 cm Planar imaging
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