Fp7 fmtxct project umce hgugm first year activity report partner fihgm
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FP7 FMTXCT Project UMCE-HGUGM first year activity report Partner FIHGM. Laboratorio de Imagen M é dica. Medicina Experimental Hospital Universitario Gregorio Mara ñó n, Madrid. Workpackage 2: XCT development Workpackage 8: FMT-XCT imaging accuracy versus PET-XCT.

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FP7 FMTXCT Project UMCE-HGUGM first year activity report Partner FIHGM

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FP7 FMTXCT ProjectUMCE-HGUGM first year activity report Partner FIHGM

Laboratorio de Imagen Médica. Medicina Experimental

Hospital Universitario Gregorio Marañón, Madrid


  • Workpackage 2: XCT development

  • Workpackage 8: FMT-XCT imaging accuracy versus PET-XCT


Workpackage 2: XCT development

  • Use of X-ray contrast agents

  • Double exposure techniques

  • Dual energy X-ray source


CT System Outline

Mechanical Design


Multi-Energy data acquisition/processing

New Tube Features


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


Detector Dynamic Range Expansion

Dual-Exposure technique

Dataset #1

Dataset #2


Detector Dynamic Range Expansion

Dual-Exposure technique (work in progress)

Dual exposure

Single exposure

CNR (PTFE/Air) = 22.11

CNR (PTFE/Air) = 13.91


Multi-Energy data acquisition/processing

Simulated Spectra for the new tube

  • Changing filter setting

Mean Energy = 55.6 kV

Mean Energy = 66.1 kV

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


Multi-Energy data acquisition/processing

Simulated Spectra for the new tube

  • Changing X-ray tube setting

Mean Energy = 34.9 kV

Mean Energy = 66.1 kV


Use of X-ray contrast agents

Fenestra Iopamiro


Mouse

200 µA, voltage 50 kV

200 µm

Fenestra LC

Mouse

200 µA, voltage 50 kV

200 µm

Iopamiro


Mouse

200 µA, voltage 50 kV

200 µm

Iopamiro

Dynamic study


Workpackage 8: FMT-XCT imaging accuracy versus PET-XCT


Materials selection for the optical phantom construction

Silicon Ti02 Pro Jet

Polyester resin

Bulk materials

Scatterers

Absorbers

+

+

Lipid emulsions

(Intralipid)

Polymer microspheres

India ink

Water

Gelatin


Resolution is depth dependent

Diffusion approximation: One photon mean free path ≈ 1mm

Source

Things to have in mind when designing a FMT phantom.

Source

Detector


Things to have in mind when designing a FMT phantom.

Heterogeneities, surface


Fluorescent spheres, 2 mm

(Should their size vary?)

Heterogeneities

4 mm

Phantom design


FMT-XCT


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


What to measure

Resolution. FWHM of point-like source?

Quantification accuracy

Sensitivity: In-vivo specific application

PET phantom remarks


Will the imaging performance hold in the “many body imaging situation”?


PET phantom


PET phantom


PET phantom


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


FMT system


coronal Z=0.25 cm

Resultados preliminares, maniquíes:

Planar imaging

Agar based, TiO2 (scatter), Blank ink (absorption)


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