Geant4 anthropomorphic phantoms: models of the human body for radiation protection studies

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Geant4 anthropomorphic phantomsmodels of the
human body for radiation protection studies

• S. Guatelli, G. Guerrieri, M. G. Pia
• INFN Genova, Italy
• SPENVIS and Geant4 Workshop,
• Catholic University, Leuven, Belgium,
• 3-7 October 2005

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Vision

• A precise representation of the human body is
  important for accurate
• Dosimetry
• Radiation protection studies
• In space science
• To design shielding of astronauts habitats in
  transfer vehicles and surface habitats
• To study the radiation effects in astronauts
  organs

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Approaches of human body models
Mathematical phantoms The size and shape of the
body and its organs are described by analytical
expressions (planes, circular and elliptical
cylinders, spheres, cones, tori,
Voxel phantoms Based on digital images
recorded from Computer Tomography (CT) scanning
or Magnetic Resonance Imaging (MRI)
Williams et al. (1986)
Gibbs et al. (1984)
Veit et al. (1989)
NRPB
MIRD5 (1969/1972)
Petoussi-Henss et al. (2002)
Zankl Wittmann (2001)
Rosenstein (1979)
Caon et al. (1997)
Kramer/Drexler (1982/1984)
Saito et al. (2001)
Dimbylow (1995)
Jones Wall (1985)
Xu et al. (2000)
Hart et al. (1994)
Tanaka et al. (1989)
Spitzer Whitlock (1998)
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Interest on Anthropomorphic Phantoms
2005, April Monte Carlo Topical Meeting,
Tennessee Session on Tomographic Models for
Radiation Protection Dosimetry many talks about
anthropomorphic phantom (mainly voxel-based
models) - GSF Male And Female Adult Voxel Models
Representing ICRP Reference Man By K. Eckerman -
Effective Dose Ratios For The Tomographic Max And
Fax Phantoms By R. Kramer - Reference Korean
Human Models Past, Present and Future By C.
Lee - The UF Family of Paediatric Tomographic
Models By W. Bolch and C. Lee - Development And
Anatomical Details Of Japanese Adult Male/ Female
Voxel Models By T. Nagaoka - Dose Calculation
Using Japanese Voxel Phantoms For Diverse
Exposures By K. Saito - Stylized Versus
Tomographic Models An Experience On Anatomical
Modelling At RPI By X. G. Xu - Use Of MCNP With
Voxel-Based Image Data For Internal Dosimetry
Applications By M. Stabin - Application Of Voxel
Phantoms For Internal Dosimetry At IRSN Using A
Dedicated Computational Tool By I.
Aubineay-Laniece - The Use Of Voxel-Based Human
Phantoms In FLUKA By L. Pinsky - The Future Of
Tomographic Modelling In Radiation Protection And
Medicine (Panel discussion)
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Anthropomorphic phantoms in Geant4
Requirement from Space Science G4 User Community

• Ion-Nuclear Models for the Analysis of Radiation
  Shielding and Effects (IONMARSE) Contract Final
  Report (25 June 2004)

From QinetiQ
Executive Summary More general requirements
have also been identified in order to apply
Geant4 to interplanetary missions (i.e. not just
restrict requirements that address nuclearnuclear
interaction physics) A Geant4 geometry for an
anthropomorphic phantom should be developed,
which can then be used in studies to more
accurately determine the equivalent dose to
different human organs.This is important since
the effects of self-shielding from
different parts of the body can be significant.
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Scope of the project

• Development of a Geant4 package to model
  anthropomorphic phantoms

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Geant4 anthropomorphic phantom

• Geant4 offers the capability to model both voxel
  and mathematical phantoms
• Voxel phantom parameterised volumes
• Analytical phantoms CSG and BREPS volumes
• Accurate description of biological materials

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Voxel phantoms in Geant4

• A DICOM interface is available in Geant4 to
  model human phantoms starting from DICOM files

3D patient anatomy
DICOM file
Acquisition of CT image
Developed by L. Archambault, L. Beaulieu, V.-H.
Tremblay (Univ. Laval and l'Hôtel-Dieu,Québec)
and improved by S. Chauvie, S. Guatelli, A.
Kimura, M. G. Pia, T. Sasaki
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Mathematical phantomsin Geant4

• Development of the following analytical phantoms
  in Geant4
• K. F. Eckerman, M. Cristy, J. C. Ryman
• (The ORNL Mathematical Phantom Series)
• http//homer.ornl.gov/vlab/VLabPhan.html
• W. S. Snyder, M. R. Ford, G. G. Warner, H. L.
  Fisher jr
• (MIRD Pamphlet 5 Revised Estimates of
  absorbed fraction for monoenergetic photon
  sources uniformly distributed in various organs
  of a heterogeneous phantom, J Nucl Med Suppl 3,
  1969)

Established reference data
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Geant4 Phantom Package

• Novel approach thanks to an advanced OO design
• Possibility to have both voxel and analytical
  phantoms in the same environment
• Possibility to compose a phantom out of different
  analytical models
• Mix and match voxel and analytical components
• Optimize the CPU and memory resources and
  accuracy of the simulation

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Software process

• Quality and reliability of the software are
  essential requirements
• Iterative and incremental process model
• Develop, extend and refine the software in a
  series of steps
• Get a product with a concrete value and produce
  results at each step
• Assess quality at each step
• Rational Unified Process (RUP) adopted as process
  framework
• Mapped onto ISO 15504

adopt a rigorous software process
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Summary of software products

• User Requirements
• Analysis and design
• Implementation
• Tests

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User Requirements
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Anthropomorphic phantom URD (1)

• The anthropomorphic model includes the body
  components

Body regions trunk, neck, head, legs, male
genitalia
Skeletal system leg bone, arm bone, pelvis,
spine, cranium, facial skeleton, skull,
rib cage, clavicles, scapulae
Gastrointestinal tract and contents esophagus,
stomach, intestine
Heart and contents outer surface of heart, left
ventricle, right ventricle, left atrium,
right atrium, heart
Organs adrenals, brain, breasts, gall bladder,
kidney, liver, lung, ovary, pancreas, skin,
spleen, testes, thymus, lobes of
thyroid, urinary bladder, uterus
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Anthropomorphic phantom URD (2)

• Composition of tissues
• The user shall be able to define composition of
  each tissue
• The user shall be able to associate a defined
  material to an organ of the phantom

• Event
• The user shall be able to retrieve the position
  and material of the body region
• traversed by tracks

• User interface
• The user shall be able to select a phantom by the
  sex, age and the model
• The user shall be able to define a phantom using
  parts derived from different
• models
• The user shall be able to create specific body
  region corresponding to subset of
• the phantom

• Visualisation
• The user shall be able to visualize the
  geometrical set-up
• The user shall be able to visualize the particle
  tracks

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Anthropomorphic phantom design

• Domain decomposition
• Abstraction of the process of the building a
  phantom
• Abstraction of the description of a phantom
  model

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The Builder design pattern has been adopted to
control the definition of anatomy components in
the phantom
Abstract Factory

• The Abstract Factory design pattern is adopted
  to define anatomic structures
• The user can select organs communicating with
  the abstract interface G4VBodyFactory,
  independently from their concrete classes

Builder
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Implementation

• G4Ellipsoid
• Use of GDML
• G4 Anthropomorphic phantoms

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New solid in Geant4 G4Ellipsoid

• Most of the organs can easily be approximated by
• Ellipsoid
• Circular and elliptical oblique cone
• Elliptical cone
• Torus with elliptical section

not implemented in the Geant4 Geometry!

• G4EllipticalCone
• Implemented by D. Anninos (CERN, Cornell
  University, USA)

G4Ellipsoid and G4Elliptical Cone available from
next public G4 Release
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GDML Geometry Description Markup Language
Solids CSG solids - box - tube -
cone - sphere - parallelepiped -
trapezoid - general trapezoid Boolean
solids - union - subtraction -
intersection

• GDML is used to define organs in terms of
  geometry, position and rotation in the
  experimental set-up, material
• GDML has been extended with the ellipsoid
• The GDML Processor is now able to handle an
  ellipsoid

Material definitions - isotopes -
elements - complex materials - molecules
- mixtures built from elements and/or
other complex
materials by fractional mass

• The GDML package has been extended to create
  parameterised volumes for the elliptical tube

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How to use the G4Phantom

• Work in progress, current status below
• The GDML files contain the information concerning
  the organs
• The user can choose to define the entire
  anthropomorphic phantom (ORNL or MIRD) or just
  some organs through the interactive session
• The user can choose interactively
• phantom by sex
• phantom by model (ORNL, MIRD or mix)
• The user can set organs sensitive
• The energy deposit given by both primary and
  secondary particles is collected in sensitive
  volumes

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Female ORNL Anthropomorphic Phantom

• Three materials used to model human tissues
• Skeleton,
• Lungs,
• Soft tissue

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Female ORNL Anthropomorphic Phantom
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Female ORNL Anthropomorphic Phantomgt Run 1 lt
Particle gamma Energy 100. MeV no. Particle
20 Beam Direction along Z axis Visualization
system OpenGL
Output of run 1
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Use of the ORNL phantom in a radioprotection study

• The anthropomorphic phantom can be used in Geant4
  application to evaluate the dose in human organs
• The anthropomorphic phantom has been integrated
  in the REMSIM Geant4 application for a
  radioprotection study in the interplanetary space
  
• The anthropomorphic phantom can be used also in
  other Geant4 space science applications

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Shielding study of vehicle concept

• Relative comparison of alternative shielding
  solutions for transfer vehicles of astronauts to
  Mars

GCR protons are incident on the vehicle
concept Simplified Inflatable habitat
complemented by water shielding
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First results
Preliminary

• Calculation of the dose in the anthropomorphic
  phantom

Preliminary
Preliminary
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Conclusions
Analytical phantoms

• Novel approach to model anthropomorphic phantoms
• Voxel phantoms
• Analytical phantoms
• Mix and match voxel/analytical
• in the same simulation environment
• Analytical anthropomorphic phantoms have been
  implemented in Geant4
• Further developments in progress
• The MIRD and ORNL analytical models will be
  released in a Geant4 advanced example in December
  2005
• The G4 anthropomorphic phantom is easy to
  integrate in Geant4 applications

Customized Phantom
Voxel phantoms (DICOM interface)