Anthropomorphic Phantoms Analytical and voxel models Status and perspectives

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Anthropomorphic Phantoms Analytical and voxel
models Status and perspectives
Giorgio Guerrieri July 13th, 2005
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A wide panorama of phantoms
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Interest on Anthropomorphic Phantoms
2005, April Monte Carlo Topical Meeting,
Tennessee In the session about Tomographic
Models for Radiation Protection Dosimetry, many
talks about anthropomorphic phantom (mainly
voxel-based models) have been presented - GSF
Male And Female Adult Voxel Models Representing
ICRP Reference Man By Keith Eckerman - Effective
Dose Ratios For The Tomographic Max And Fax
Phantoms By Richard Kramer - Reference Korean
Human Models Past, Present and Future By
Choonsik Lee - The UF Family of Paediatric
Tomographic Models By Wesley Bolch and Choonik
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 Kimiaki Saito -
Stylized Versus Tomographic Models An Experience
On Anatomical Modelling At RPI By X. George Xu -
Use Of MCNP With Voxel-Based Image Data For
Internal Dosimetry Applications By Michael
Stabin - Application Of Voxel Phantoms For
Internal Dosimetry At IRSN Using A Dedicated
Computational Tool By Isabelle
Aubineay-Laniece - The Use Of Voxel-Based Human
Phantoms In FLUKA By Larry Pinsky - The Future Of
Tomographic Modelling In Radiation Protection And
Medicine (Panel discussion)
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Anthropomorphic Phantoms for Geant4 toolkit

• The representation of the human body is useful
  for radiation protection and medical
  physic simulation applications.
• In particular for applications in radiation
  shielding of habitats
• for astronauts, such as transfer vehicles and
  surface habitats
• for future manned exploration missions.
• The development of anthropomorphic phantoms,
  together with Geant4 physics
• modelling, makes possible to study the radiation
  damage to the astronauts' organs during
  interplanetary missions.
• The models of anthropomorphic phantoms can be
  used not only in space science, but also for
  cancer therapy studies too.

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Anthropomorphic Phantoms for Geant4 toolkit
The project for Geant4 toolkit is addressed to
develop anthropomorphic phantom that can be
entirely customized by the user. As in URD, the
user shall be able to - Choose model for each
body part to add to the phantom (ORNL, MIRD) -
Add single voxel-based body part from DICOM file
(CT, MRI)
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Analytical Model
The anatomies of new-born, and children of age 1
year, 5 year, 10 year, 15 year and adult male and
female had been modelled at the Oak Ridge
National Laboratory by Cristy and Eckerman
(1987).
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Modelling with geometries
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Final result
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Anthropomorphic Phantom URD (1)

• - The goal of the project is the development of
  a Geant4 package addressed to the modelingof an
  anthropomorphic phantom providing a realistic
  description of the human body and anatomy.
• - The phantom consists of a mathematical model
  of

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• The anthopomorphic phantom will be implemented
  exploiting the object oriented technology
• A rigorous software process is adopted.
• The object oriented technology allows
  extensive code reuse, flexibility, easy
  extension of the software.

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

The Abstract Factory provides an interface for
creating families of related object without
specifying their concrete classes.
It makes exchanging product families easy. It
can use different product configurations simply
by changing the concrete factory.
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The creational pattern Builder separates the
construction of a complex object from its
representation so that the same construction
process can create different representations.
The Builder object provides the director with an
abstract interface for constructing the
product. Thanks to the abstract interface
G4VPhantomBuilder, all one has to do to change
the product's internal representation is
define a new kind of builder.
Unlike creational patterns that construct
products in one shot, the Builder pattern
constructs the product step by step under the
director's control.
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Problems
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G4Ellipsoid
The ellipsoid and part of it are used to
describe several organs like stomach, ovaries,
brain, or lungs and kidneys...
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1-Dimensional Test
This test consisted of 1D-flux of geantinos with
direction parallel to X axis impinging onto an
ellipsoid. The ellipsoid has semi-axis lengths
a 7. µm , b 10. µm, c 15. µm. The solid is
spaced in an enclosed box volume defined world
which sizes are 40.µm. The number of events
generated in the test is 104. The same test was
performed for 1D-beams with direction parallel to
Y and Z directions. The path length of the
geantinos was verified to be equal to the sizes
of the ellipsoid, as expected.
Path Length
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2-Dimensional Test
This test consisted of an isotropic flux of
geantinos impinging onto an ellipsoid. The
ellipsoid has semi-axis lengths a 7. µm, b
10. µm, c 15. µm. The solid is spaced in an
enclosed box volume defined world which sizes are
40 µm. The number of the events generated in the
test is 5 105.
Projection on plane XY, YZ, ZX
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G4Ellipsoid
The new class G4Ellipsoid is meant to be
publicly available in the next Geant4 release.
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GDML Geometry Description Markup Language
The Geometry Description Markup Language
work-package is meant to provide geometry data
exchange format for the LCG applications. The
work-package consists of the GDML Schema part,
which is a fully self-consistent definition of
the GDML syntax, and the GDML I/O part, which
provides means for writing out and reading in
GDML files.
What users gain is the reduced time when writing
their geometry description as no need for
re-compilation and re-linking of their
applications is required even for one number
change. The other advantage is that it allows
them easy exchange of geometry data without a
need to reveal their source code and makes life
easier for developers as well because they can
use the GDML data for tracing bugs and problems
in geometry processing code.
The GDML work-package can be useful for simplify
geometry description of body parts
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Problems
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Extending GDML
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Implementation of an anthropomorphic phantom
example
We have explored GDML functionality for a
preliminary implementation of an example of an
analytical anthropomorphic phantom.

• Elements of Human phantom example
• Primary Particle
• Geometry
• Physics
• Messengers

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Primary Particle
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Geometry
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Materials
Materials are defined in GDML file There are
three materials defined for different body
parts - Skeleton for the parts of skeleton
system - Lung for the lungs - Soft Tissue
for all other body part These are defined by
their elemental composition and densities.
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Sensitive Body Part
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Messengers
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Example of geometry setup
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Female ORNL Anthropomorphic Phantom
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Female ORNL Anthropomorphic Phantom
Skull
Spine
Thyroid
Esophagus
Lungs
Arm Bones
Breasts
Spleen
Heart
Pancreas
Stomach
Liver
Kidneys
Upper Large Intestine
Pelvis
Ovaries
Uterus
Lower Large Intestine
Urinary Bladder
Leg Bones
Not visible Brain (in the skull)
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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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Female ORNL Anthropomorphic Phantomgt Run 2 lt
Particle gamma Energy 100. MeV no. Particle
20 Beam Direction along X axis Visualization
system OpenGL
Output of run 2
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Conclusions

• A new solid ellipsoid has been designed,
  implemented and tested to extend the Geant4
  geometry package.The solid enables the
  representations of many body parts.
• GDML work-package has been extended and now it's
  able to read the ellipsoid from Geant4 geometry
  and to create volumes parametrized of elliptical
  tube.
• GDML work-package seems to be useful to simplify
  the geometry description of the analytical
  anthropomorphic phantom.

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Future

• Development of a prototype of analytical
  anthropomorphic phantom to be used in simulation
  applications of radioprotection study or medical
  physics.
• Allow user to build customized anthropomorphic
  phantom with organs described by analytical model
  and DICOM interfacecreating a voxel-analytical
  phantom.

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Anthropomorphic Phantoms Analytical and voxel
models Status and perspectives
Giorgio Guerrieri July 13th, 2005