1. Overview of Geant4 applications in Medical Physics
2003 IEEE Nuclear Science Symposium
And Medical Imaging Conference
Tuesday, 21st October, 2003
Portland, Oregon, USA
Susanna Guatelli
INFN, Genova, Italy
Susanna Guatelli

2. MonteCarlo simulation is not used in clinical practice
MonteCarlo Methods in radiotherapy
MonteCarlo methods have been explored for years as a tool for precise
dosimetry, in alternative to analytical methods
De facto,
MonteCarlo simulation is not used in clinical practice
(only side studies)
Challenge : develop MC
for clinical use
The limiting factor is the speed
Other limitations:
Reliable?
For “software specialists only”, not user-friendly for general practice

3. Specific facilities controlled by a friendly UI
Extensibility to accommodate new user requirements (thanks to the OO technology)
A rigorous
software process
The transparency of physics
Independent validation
by a large user community worldwide
Use of evaluated data libraries
Adoption of standards wherever available
(de jure or de facto)
User support from experts

4. Geant4
Geant4
Geant4 is an Object Oriented Toolkit for the simulation of the passage of particles through matter.
Its application areas include high energy and nuclear physics experiments, astrophysics, medical physics, radiation background studies, radioprotection and space science
Geant4 exploits advanced Software Engineering techniques and Object Oriented technology
Geant4 has been developed and maintained by a world-wide collaboration of more than 100 scientists
The source code and libraries are freely distributed from the Geant4 web site
Katsuya Amako: Geant4 Simulation Toolkit: Overview and Its Object-Oriented Design , 22 October, 8.15
useful links:

5. Geant4 applications in Medical Physics
Verification of conventional radiotherapy treatment planning
(as required by protocols)
Investigation of innovative methods of radiotherapy
Radiodiagnostic
Dosimetric studies at cellular level

6. Detailed set-up description and efficient navigation
Geometry
Detailed set-up description and efficient navigation
CSG (Constructed Solid Geometries)
simple solids
BREPS (Boundary REPresented Solids)
volumes defined by boundary surfaces
polyhedra, cylinders, cones, toroids etc.
Boolean solids
union, subtraction…
ATLAS
Proton line beam
Fields: variable non-uniformity and differentiability

7. Geant4-Dicom interface
Reproduce patient’s
anatomy in a Geant4 application
Modelisation of complex
structures
file
Developed by L. Archambault, L. Beaulieu, V.-H. Tremblay
(Univ. Laval and l'Hôtel-Dieu, Québec)

8. Modelisation of beam lines Modelisation of electromagnetic field
Head Radiotherapy
IntraOperative Radiation Therapy(IORT)
High energy electron beam, 50 MeV
Electron beam
Karolinska Institutet,
Stockholm
Susanne Larsson
Roger Svensson
Irena Gudowska
Björn Andreasen
IORT Novac7
The title of my PhD project is:
Design and experimental verification of narrow scanned photon beams for IMRT and 3D PET-CT monitoring.
But I put “Treatment head development” on the slide as it is shortes. Change if u want. You can also change and only have my name on the slide if you want. Up to you.
The aim of this technique is to produce fast intensity modulated photon dose delivery especially useful for radiobiological optimised radiation therapy.
(the profiles in the middle if the picture illustrates the intensity modulated dose)
(Treatmenthead in the top of the picture)
We use a new thin transmission target technique for dose delivery. We produce narrow scanned photon beams.
High-energy, MeV, electron beams of low emittance incident on thin low-Z targets produce very narrow intense high-energy bremsstrahlung beams.
However, electrons are transmitted through the target and they have to be bent from the therapeutic field by a purging magnet and completely absorbed in an electron collector.
(PET-CT illustration in the bottom)
This technique is also suitable for 3D in vivo dose delivery verification of the distribution by PET-CT imaging of the induced b+ activity.
What I do:
I have done simulations of the particle transport of the beam production. I use the most vital components in my simulation:
50 MeV electron beam. Higher energy produces more narrow beam as the scattering of the photons, the intrinsic bremsstrahlung process and the electron multiple scattering in the target are in approximately proportional to the mean energy of the electrons. Now the machine normally works in 6 MeV.
3 mm Be Target. A thin target made of a material with low atomic number produces a narrow photon beam with high intensity in the forward direction due to less multiple scattering and also less photon absorption.
3D Magnetic field. 3D grid plus physical volume of iron of the pole gap. I import an externally produced 3D magnetic field grid in the simulations.
Electron Collector made of tungsten (W). The choice of material is essential to achieve maximum absorption of the transmitted electrons. There will be more initial bremsstrahlung photon production in a high atomic number collector than in a low atomic number collector. A high atomic number collector has significantly stronger attenuation of photons due to the higher density and photon attenuation coefficient. Therefore, the electron collector made of high atomic number material will not only stop the electrons in a shorter distance but also attenuate the bremsstrahlung photons produced in the collector more effectively per unit thickness. This will give lower photon energy fluence after the collector. I choose W as it is a material with high atomic number and it is quite common and fairly cheap. Osmium and rhenium for example less common and more expensive.
I have done Investigations of design and location of the electron collector have been done in order to minimise secondary electron and photon contamination of the therapeutic beam. I need more simulations with different materials and designs off course.
What other people do:
Björn Andreasen is developing the magnet in the OPERA-3d module TOSCA manufactured by VECTOR FIELDS Ltd.
Another PhD student (Sara Janek) is doing research on the PET-CT dose delivery verification. I will also do Geant4 simulations on foto-nuclear phantoms later.
Roger Svensson, Irena Gudowska and Anders Brahme is supervising us.
G. Barca*, F. Castrovillari**, D. Cucè**,
E. Lamanna**, M. Veltri*
* Azienda Ospedaliera (Hospital) of Cosenza
**Physics Dep., UNICAL & INFN, Cosenza
Susanna Guatelli

9. GATE Collaboration PEM Positron Emission Mammography (PEM)
Geant4 application for tomographic emission (GATE) is a recently developed simulation platform based on Geant4, specifically designed for PET and SPECT studies.
Experimental set-up changing
with time
Talk:
Steven Staelens, Overview of GATE,
PEM
Positron Emission Mammography (PEM)
Talk:
A. Trindade
Geant4 Applications and Developments for Medical Physics Experiments

10. Electromagnetic physics
Multiple scattering
Bremsstrahlung
Ionisation
Annihilation
Photoelectric effect
Compton scattering
Rayleigh effect
g conversion
e+e- pair production
Synchrotron radiation
Transition radiation
Cherenkov
Refraction
Reflection
Absorption
Scintillation
Fluorescence
Auger
electrons and positrons
gamma, X-ray and optical photons
muons
charged hadrons
ions
High energy extensions
LowEnergy extensions
Alternative models for the same process
needed for LHC experiments, cosmic ray experiments…
fundamental for medical applications
Data driven, Parameterised and theoretical models
Cross section data sets: transparent and interchangeable
the most complete hadronic simulation kit on the market
alternative and complementary models
Hadronic physics

11. Dosimetric validations
Geant4 dosimetric validations
Validation is fundamental for Medical Physics Applications
The validation process includes different levels
Microscopic validation: physics models validation
Macroscopic validation: experimental set-up validation
Validation in respect to experimental measurements
Macroscopic
validation
Microscopic
validation
See S. Guatelli, Precision Validation of Geant4 Electromagnetic
Physics (22 October)
See G.Folger, Validation of Geant4 Hadronic Physics (22 October)
Talk J.F Carrier:
Validation of GEANT4 for Simulations in Medical Physics

12. Brachytherapy Low Energy Physics for accurate dosimetry
Dosimetry for all brachytherapic
devices
Collaboration of frameworks
Analysis, UI, Visualisation, Access
to distributed resources
Talk:
S. Guatelli
From DICOM to GRID: a dosimetric system for brachytherapy born from HEP

13. Hadron therapy Hadrontherapy Electromagnetic and hadronic interactions
for protons, ions(and secondary particles)
Proton beam line
Talk:
P. Cirrone
Implementation of a New Monte Carlo Simulation Tool for the Development of a Proton Therapy Beam Line and Verification of the Related Dose Distributions

14. Metabolic Therapy with 131I
Isotope accumulated in the damaged lobe can destroy pathological cells without any surgical operation
131I  131Xe + - + 
Radioactive Decay Module  -
131I
131Xe (excited)
131Xe (stable)
G. Barca*, F. Castrovillari**, D. Cucè**,
E. Lamanna**, M. Veltri*
* Azienda Ospedaliera (Hospital) of Cosenza
**Physics Dep., UNICAL & INFN, Cosenza

15. explore the solar system and the Universe
Shielding and radioprotection in space missions
Collaboration ESA, ALENIA SPAZIO, INFN Genova in AURORA project
G.Brambati1,V.Guarnieri1, S.Guatelli2, C. Lobascio1,P.Parodi1, M. G. Pia2
1.ALENIA SPAZIO, Torino, Italy,2.INFN Genova, Italy
Geant4 application not only
in hospital treatments
AURORA
explore the solar system and the Universe
Geant4 application for
shielding and astronauts’
radioprotection studies

16. in chemistry and biochemistry
Simulation of Interactions of Radiation with Biological Systems at the Cellular and DNA Level
Geant4-DNA
Geant4 applications
in chemistry and biochemistry

17. Dosimetry at cellular level
Light-ion microbeams provide a unique opportunity to irradiate biological samples at the cellular level and to investigate radiobiological effects
Accurate description at cellular level
Talk S. Incerti:
Simulation of cellular irradiation with the CENBG microbeam line using GEANT4

18. How to achieve quick response?

19. Network
network of Personal Computer as a realistic alternative to a high-costs dedicated parallel hardware to be used in clinical practice
Talk S. Schauvie:
Radiotherapy treatment planning with Monte Carlo on a distributed system S. Chauvie1,2, G. Scielzo1  1Ordine Mauriziano - IRCC  2INFN 

20. Parallel mode:distributed resources
Distributed Geant4 Simulation
talk: DIANE -- Distributed Analysis Environment for GRID-enabled Simulation and Analysis of Physics Data (Friday 24th October)
Susanna Guatelli

21. Conclusions
Geant4 is a powerful and reliable tool for medical physics studies
adoption of rigorous software process
Transparency of the physics
Alternative and complementary physics models
Accurate description of experimental set-up
Many applications in Medical Physics and Medical
Imaging
Valid example of technology transfer
Integration to the GRID offers quick response