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

1. Geant4 anthropomorphic phantoms:models 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 SPENVIS and Geant4 Workshop

2. 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 SPENVIS and Geant4 Workshop

3. 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) SPENVIS and Geant4 Workshop

4. 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) SPENVIS and Geant4 Workshop

5. Anthropomorphic phantoms in Geant4 Requirement from Space Science G4 User Community 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. Ion-Nuclear Models for the Analysis of Radiation Shielding and Effects (IONMARSE) – Contract Final Report (25 June 2004) SPENVIS and Geant4 Workshop

6. Scope of the project Development of a Geant4 package to model anthropomorphic phantoms SPENVIS and Geant4 Workshop

7. 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 SPENVIS and Geant4 Workshop

8. 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 byS. Chauvie, S. Guatelli, A. Kimura, M. G. Pia, T. Sasaki SPENVIS and Geant4 Workshop

9. 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 SPENVIS and Geant4 Workshop

10. 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 SPENVIS and Geant4 Workshop

11. 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 SPENVIS and Geant4 Workshop

12. Summary of software products User Requirements Analysis and design Implementation Tests SPENVIS and Geant4 Workshop

13. User Requirements SPENVIS and Geant4 Workshop

14. 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 SPENVIS and Geant4 Workshop

15. 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 SPENVIS and Geant4 Workshop

16. Anthropomorphic phantom: design • Domain decomposition: • Abstraction of the process of the building a phantom • Abstraction of the description of a phantom model SPENVIS and Geant4 Workshop

17. Design patterns The Builder design patternhas 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 SPENVIS and Geant4 Workshop

18. Implementation G4Ellipsoid Use of GDML G4 Anthropomorphic phantoms SPENVIS and Geant4 Workshop

19. 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) 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 SPENVIS and Geant4 Workshop

20. 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 SPENVIS and Geant4 Workshop

21. 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 SPENVIS and Geant4 Workshop

22. 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) Female ORNL Anthropomorphic Phantom • Three materials used to model human tissues: • Skeleton, • Lungs, • Soft tissue SPENVIS and Geant4 Workshop

23. Female ORNL Anthropomorphic Phantom SPENVIS and Geant4 Workshop

24. 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 Female ORNL Anthropomorphic Phantom> Run 1 < Particle: gamma Energy: 100. MeV no. Particle: 20 Beam Direction: along Z axis Visualization system: OpenGL Output of run 1 SPENVIS and Geant4 Workshop

25. 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 SPENVIS and Geant4 Workshop

26. phantom GCR p, 106 events 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 SPENVIS and Geant4 Workshop

27. First results Preliminary • Calculation of the dose in the anthropomorphic phantom Preliminary Preliminary SPENVIS and Geant4 Workshop

28. 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) SPENVIS and Geant4 Workshop