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  • Selling your ideas is challenging. First, you must get your listeners to agree with you in principle. Then, you must move them to action. Use the Dale Carnegie Training® Evidence – Action – Benefit formula, and you will deliver a motivational, action-oriented presentation.
  • http://www.irus.rri.on.ca/~pslomka/research00.html Nuclear Medicine is an imaging modality which provides valuable and often unique information about the function of various organs by imaging the distribution of radiopharmaceuticals inside patient’s body. AUTOMATED MULTIMODALITY IMAGE REGISTRATION Due to the low resolution of functional images (SPECT, PET ) it is desirable to integrate the functional information with the anatomical information obtained from other modalities, usually Magnetic Resonance Imaging (MRI) and Computed Tomography (CT). howstuffworks Imaging in Nuclear Medicine One problem with the human body is that it is opaque, and looking inside is generally painful. In the past, exploratory surgery was one common way to look inside the body, but today doctors can use a huge array of non-invasive techniques. Some of these techniques include things like X-rays, MRI scanners , CAT scans, ultrasound and so on. Each of these techniques has advantages and disadvantages that make them useful for different conditions and different parts of the body. Nuclear medicine imaging techniques give doctors another way to look inside the human body. The techniques combine the use of computers , detectors, and radioactive substances. These techniques include: Positron emission tomography (PET) Single photon emission computed tomography (SPECT) Cardiovascular imaging Bone scanning All of these techniques use different properties of radioactive elements to create an image. See How Radioactivity works for complete details. Nuclear medicine imaging is useful for detecting: tumors aneurysms (weak spots in blood vessel walls) irregular or inadequate blood flow to various tissues blood cell disorders and inadequate functioning of organs, such as thyroid and pulmonary function deficiencies. The use of any specific test, or combination of tests, depends upon the patient's symptoms and the disease being diagnosed. Single Photon Emission Computed Tomography (SPECT) SPECT is a technique similar to PET. But the radioactive substances used in SPECT (Xenon-133, Technetium-99, Iodine-123) have longer decay times than those used in PET, and emit single instead of double gamma rays. SPECT can provide information about blood flow and the distribution of radioactive substances in the body. Its images have less sensitivity and are less detailed than PET images, but the SPECT technique is less expensive than PET. Also, SPECT centers are more accessible than PET centers because they do not have to be located near a particle accelerator.

talk talk Presentation Transcript

  • GATE ( G eant4 A pplication for T omographic E mission): a PET/SPECT general-purpose simulation platform G.Santin (ESA-ESTEC & Trieste University) D.Strul, C.Morel (Lausanne University) (for the OpenGATE Collaboration)
  • Imaging in Nuclear Medicine
    • Anatomical imaging
      • X-rays, MRI scanners, CAT, ultrasound
      • Detailed info about the tissue structure and composition
    • Functional imaging
      • In vivo physiologic analysis
      • Spatial distribution (and evolution! ) of radio nuclides in the body (pharmacokinetics, metabolism)  We see the organ during its activity
      • Quantitative analysis (concentrations)
    • PET:
      • Biological molecules tagged with radioactive isotopes with short life-time ( 15 O  T 1/2 ~2 min, 11 C  20 min)
      • Resolution down to a few mm 3
    • SPECT:
      • Longer decay times ( 99m Tc  6 h, 123 I  13 h , 133 Xe  5 d)
        • no need for accelerator facilities
      • Poorer sensitivity (and resolution)
    • Multimodality
      • Due to low resolution  recently often associated to other modalities of scanning (MRI, CT)
  • Simulations in Nuclear Medicine
    • Wide range of applications
      • scanner design, image reconstruction, scatter correction, protocol optimization,…
    • Analytical computations
    • Since a couple of decades: accurate Monte Carlo simulations are widely used in parallel to analytical computations or experimental studies for a large range of PET and SPECT applications
      • Non exaustive list
    • Computation time
      • Is still a concern
      • (  see later)
  • Two approaches…
    • Dedicated simulation programs (PETsim, SimSET, Eidolon,… )
      • Simple geometry, limited number of requirements
      • Fast development
      • Optimized on application
      • Limits in the physics description
      • Maintenance, upgrades?
    • General purpose simulation codes (Geant4, EGS4, MCNP)
      • Wide community of developers and users
      • code and physics validation
      • documentation and support
      • Complexity
      • Speed
  • GATE
    • Based on Geant4
      • Physics description
      • Long term availability
      • Upgrades , documentation & support
      • Object Oriented Analysis & Design
    • Extensions to build a simulation platform for PET/SPECT
      • Ease of use for non C++ programmers
        • scripting almost everywhere, geometry included…
      • Typical Nuclear Medicine options included
        • material database, sources, readout,…
    • AND MORE !
      • Time management
      • Movements
  • How it works
    • 3 different layers
    • Developer level
      • Framework and application classes
      • C++ programming
    • User level
      • Simulation parameters
        • Geometry
        • Sources
      • Scripting only
    User Interface Application classes Framework Geant4
  • GATE detailed structure Geometry mgr Specific I/O Source scripting Source mgr Time mgr Analysis mgr I/O mgr Geometry scripting I/O choice scripting Specific source type Specific source Geant4 Specific analysis Analysis scripting Timing scripting Specific volume User Interface
  • Geometry scripting world D.Strul Uni Lausanne Source Body Head Scanner Rsector Crystal LSO BGO
  • Geometry examples SPECT S. Staelens, Univ. Ghent PET Collimator detail
  • Source management
    • Multiple sources
      • Controlled by source manager
      • Inserted via scripting
      • Complex geometries: customized GPS
    • Optimized decay
      • Customized G4 Radioactive Decay Module (RDM)
      • PET-specific sources
    • An example:
      • Dual isotope scan
      • Simulation for independent time frames
        • 0-2 and 14-16 min
  • Timing
    • Simulation time
      • A clock models the passing of time during experiments
      • The user defines the experiment timing
    • Time-dependent objects
      • Updated when time changes
      • Allows programming of movement, tracer kinetics...
    0s 20s 40s 60s
  • Sensitive volumes and digitisation
    • Pre-programmed components
      • Sensitive detectors
      • Trajectory analyser
    • Digitizer
      • Linear signal processing chain
      • Modular : set-up via scripting
    Hits Energy response Spatial response Centroid readout Threshold Electronics Digis
  • Data output
    • Pluggable output modules
      • Multiple parallel output channels  ROOT, ASCII…
      • Include features for real-time display
    Output management ASCII ROOT Binary format GATE
  • Validation
    • Several SPECT/gamma camera projects
      • Clermont-Ferrand
      • Ghent
    • PET validation work to start soon
      • Lausanne, ….
    D. Lazaro, LPC-IN2P3, Clermont-Ferrand IASA gamma camera
  • Toward parallel computation
    • Computation speed is essential
      • “ Simple” geometry
      • But: voxels, huge number of events, …
    • Projects
      • LAN parallelisation
      • Implementation on DATAGRID (W.I.P.)
    Input file Data base file Input file exploding Output file merging Grid-GATE output file Output result file GATE on the Grid Data base file D. Lazaro, LPC-IN2P3, Clermont-Ferrand
  • OpenGATE collaboration
    • Shared development
      • Optimal use of manpower and skills
      • Long-term maintenance and support
      • Coordination of efforts
      • Multiple development axes : tool implementation, validation, …
    • Current composition
      • 10 groups
      • Fields: SPECT, PET,  PET
      • Application: design, validation
    • All members contribute
      • According to their interests and know-how
      • On a best-effort basis
    • Coordination
      • A spokesman
      • Steering committee (one delegate/member)
      • Technical meetings
  • Summary
    • On-going project
      • Develop a versatile simulation platform for PET/SPECT
      • Build a shared-development collaboration
      • Development and validation work on their way
    • For more info
      • http://www-iphe.unil.ch/~PET/research/gate/
    The End