SU-C-201-07: Validation of a GATE Gamma Camera Model for the Siemens Symbia

Authors

  • Mikell J,

    1. Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, TX
    2. University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX
    3. Christiana Care Hospital, Newark, DE
    4. Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston TX
    5. Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, PA
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  • Siman W,

    1. Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, TX
    2. University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX
    3. Christiana Care Hospital, Newark, DE
    4. Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston TX
    5. Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, PA
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  • Mourtada F,

    1. Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, TX
    2. University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX
    3. Christiana Care Hospital, Newark, DE
    4. Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston TX
    5. Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, PA
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  • Kappadath S

    1. Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, TX
    2. University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX
    3. Christiana Care Hospital, Newark, DE
    4. Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston TX
    5. Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, PA
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Abstract

Purpose:

To develop a simulation model of a clinical gamma camera/SPECT system and to validate the model using experimental and published measurements from the clinical system.

Methods:

Geant4 Application for Tomographic Emission (GATE) was used to create a model of the Siemens Symbia gamma camera. A modular model was implemented that allows specifying combinations of crystal thickness (3/8”, 5/8”) and collimator (LEHR, MELP, HE). Shielding, energy resolution, intrinsic resolution, crystal thickness, and collimator properties were set based on manufacturer specifications. Validation of the model was performed by simulating NEMA 2007 gamma camera tests including spatial resolution and sensitivity for Tc99; these were compared with experimental and published data for the scanner. The simulated energy spectra of a Tc99 line source in acrylic blocks was visually compared with the corresponding experimental acquisition. For a 4 cm diameter sphere filled with Tc99, the attenuation maps were generated from simulation data, and the photopeak and scatter window were extracted from GATE output using ROOT to create DICOM files to use in the clinical reconstruction.

Results:

Simulated spatial resolutions for LEHR 3/8” crystal at 0, 10 cm, 10 cm (with scatter), and 30 cm were 4, 6.7, 7.9, and 14.5 mm FWHM; these were 9% less than published data. For 5/8” crystal the spatial resolutions were 4.5, 7.0, 8.5, and 14.7 mm FWHM; these were 4% to 10% less than published data. Simulated sensitivity was within 3.5% of published data for both LEHR 3/8” and 5/8”. The simulated energy spectra matched the photopeak and scatter window well, but did overestimate the counts below 90 keV. The simulated attenuation map and projection data were successfully reconstructed with the clinical software, and the passed visual inspection.

Conclusions:

Validation of a specific clinical scanner allows future studies of quantification accuracy for both planar and SPECT imaging.

Research reported in this publication was supported by the National Cancer Institute of the National Institutes of Health under Award Number R01CA138986. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

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