Seminario Geant4 INFN

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- DNA

• Multi-disciplinary Collaboration of
• astrophysicists and space scientists
• particle physicists
• medical physicists
• biologists
• physicians

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Object Oriented Toolkit for the simulation of
the passage of particles through matter
The transparency of physics
Advanced functionalities in geometry, physics,
visualisation etc.
Extensibility to satisfy new user requirements
thanks to the OO technology
Quality Assurance based on sound software
engineering
Geant4 provides various features relevant for
medical applications
Use of evaluated data libraries
Subject to independent validation by a large user
community worldwide
User support organization by a large
international Collaboration of experts
Adopts standards wherever available (de jure or
de facto)
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Low Energy Electromagnetic Physics
http//www.ge.infn.it/geant4/lowE/

• down to 250 eV for electrons and g
• based on the LLNL data libraries
• shell effects

Low Energy Electromagnetic package extends the
coverage of physics interactions

• down to 1 keV for hadrons and ions
• Bethe-Block above 2 MeV
• Ziegler and ICRU parameterisations
• (with material dependence)
• free electron gas model
• quantal harmonic oscillator model
• charge dependence (Barkas effect)

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Geant4 Low Energy Electromagnetic Physics
Photon attenuation coefficient in water
Ion ionisation
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Brachytherapy
Brachytherapy is a medical therapy used for
cancer treatments
Radioactive sources are used to deposit
therapeutic doses near tumors while preserving
surrounding healthy tissues
Geant4 allows a complete flexible description of
the real geometry
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Anisotropy
The dose deposition is not isotropic due to
source geometry and auto-absorption,
encapsulation and shielding effects
Radioactive Decay Module is
capable of handling the generation of the whole
radioactive chain of the 192Ir source
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Isodose curves
1 million 1 mm3 voxels
?-Selectron 192Ir source
The simulated source is placed in a 30 cm water
box
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Dosimetric Studies
Pixel Ionisation Chamber Relative dose with 6 MV
photons beam
Deposited energy vs Depth in water and
experimental data
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Bragg Peak of Protons in Water
Magic Cube Relative dose with 270 MeV protons
beam in water
Deposited energy vs Depth in water and
experimental data
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Work in progress

• Work in progress

• In vivo TLD dosimetry
• Simulation of the energy deposition of low energy
  photons in TLD LiF100 nanodosimeters
• Used to calculate dose to patient in
  radiodiagnostic examinations
• mammography
• virtual colonscopy

• CT image interface
• Interface between Geant4 and DICOM CT scan images
  format in order to perform in tissue simulation