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

Susanna Guatelli SPENVIS and Geant4 Workshop

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

S. Guatelli, G. Guerrieri, M. G. Pia

INFN Genova, Italy

SPENVIS and Geant4 Workshop,

Catholic University, Leuven, Belgium,

3-7 October 2005


VisionVision

• 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


Approaches of human body Approaches of human body modelsmodels

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)

NRPBMIRD5

(1969/1972)

Kramer/Drexler(1982/1984)Jones & Wall

(1985)

Rosenstein(1979)

Hart et al.(1994)

Gibbs et al.(1984)

Williams et al.(1986)

Veit et al.(1989)Zankl & Wittmann

(2001)

Petoussi-Henss et al.(2002)

Dimbylow(1995)

Caon et al.(1997) Saito et al.

(2001)Tanaka et al.

(1989)Xu et al.(2000)

Spitzer & Whitlock(1998)


Interest on Interest on Anthropomorphic PhantomsAnthropomorphic 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)


Anthropomorphic phantoms in Anthropomorphic phantoms in Geant4Geant4

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

Executive Summary:…More general requirements have also been identified in order to apply Geant4 tointerplanetary 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 differentparts of the body can be significant.

From QinetiQ

Requirement from Space Science G4 User CommunityRequirement from Space Science G4 User Community


Scope of the projectScope of the project

Development of a Geant4 package to model anthropomorphic phantoms


Geant4 anthropomorphic phantomGeant4 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


Acquisition of CT imageAcquisition of CT image

3D patient anatomy3D patient anatomy

DICOM file

Voxel phantoms in Voxel phantoms in Geant4Geant4

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

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


Mathematical phantomsMathematical phantomsin Geant4 in 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




Geant4 Phantom PackageGeant4 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


• QualityQuality and reliabilityreliability 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

Software processSoftware process

adopt a rigorous software process


Summary of software Summary of software productsproducts

User Requirements

Analysis and design

Implementation

Tests


User RequirementsUser Requirements


Anthropomorphic phantom: URD (1)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


Anthropomorphic phantom: URD (2)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


Anthropomorphic Anthropomorphic phantom: designphantom: design

Domain decomposition:

Abstraction of the process of the building a phantom

Abstraction of the description of a phantom model


Design patternsDesign patterns

• 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

Abstract Factory

Builder

The Builder design pattern has been adopted to control the

definition of anatomy components in the phantom


ImplementationImplementation

G4Ellipsoid

Use of GDML

G4 Anthropomorphic phantoms


New solid in Geant4: New solid in Geant4: G4EllipsoidG4EllipsoidMost 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!

G4Ellipsoid:• First version by G. Horton-Smith (Caltech, USA), • Revised by G. Guerrieri (INFN Genova) as part of this work and by D. Anninos (CERN, Cornell University, USA)

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

G4Ellipsoid and G4Elliptical Cone available from next public G4 Release


GDML: Geometry Description Markup LanguageGDML: Geometry Description Markup LanguageSolids CSG solids: - box - tube - cone - sphere - parallelepiped - trapezoid - general trapezoid Boolean solids: - union - subtraction - intersection

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

• 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

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


• 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

How to use the G4PhantomHow to use the G4Phantom


Female ORNL Anthropomorphic PhantomFemale ORNL Anthropomorphic Phantom

Thyroid

Skull

Lungs Arm Bones

Spine

Esophagus

Spleen

StomachKidneysPelvis

Ovaries

Lower Large Intestine

Leg BonesUrinary Bladder

Uterus

Upper Large Intestine

Liver

Breasts

Heart

Not visible: Brain (in the skull)

Pancreas

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


Female ORNL Anthropomorphic PhantomFemale ORNL Anthropomorphic Phantom


Female ORNL Anthropomorphic PhantomFemale ORNL Anthropomorphic Phantom> Run 1 <> Run 1 <

Particle: gamma

Energy: 100. MeV

no. Particle: 20

Beam Direction: along Z axis

Visualization system: OpenGL

TrackID: 2 -> LegBonesORNLVolume -> Energy deposit: 3.4576726 MeV TrackID: 2 -> BodyVolume -> Energy deposit: 5.1323606 MeV TrackID: 2 -> BodyVolume -> Energy deposit: 5.1711365 MeV TrackID: 2 -> BodyVolume -> Energy deposit: 701.06096 keV TrackID: 16 -> BodyVolume -> Energy deposit: 807.59738 keV TrackID: 23 -> BodyVolume -> Energy deposit: 1.497982 keV TrackID: 22 -> BodyVolume -> Energy deposit: 2.3391091 keV TrackID: 21 -> BodyVolume -> Energy deposit: 220.25512 eV TrackID: 20 -> BodyVolume -> Energy deposit: 10.468365 keV TrackID: 19 -> LegBonesORNLVolume -> Energy deposit: 16.651015 keV TrackID: 24 -> BodyVolume -> Energy deposit: 4.0614721 keV

Output of run 1


Use of the ORNL phantom in a Use of the ORNL phantom in a radioprotection studyradioprotection 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


Shielding study of vehicle conceptShielding study of vehicle concept

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

GCR p, 106 events

phantom

GCR protons are incident on the vehicle concept:Simplified Inflatable habitat complemented by water shielding


First resultsFirst results

• Calculation of the dose in the anthropomorphic phantom

Preliminary

Preliminary

Preliminary


ConclusionsConclusions

Customized Phantom

• 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

Voxel phantoms(DICOM interface)

Analytical phantoms

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

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