1. Low Energy Electromagnetic Physics PART II
Maria Grazia Pia
INFN Genova
on behalf of the Low Energy Electromagnetic Working Group
Geant4 Workshop
Helsinki, October 2003

2. Technology transfer Particle physics software aids space and medicine
Geant4 is a showcase example of technology transfer from particle
physics to other fields such as space and medical science […].
CERN Courier, June 2002

3. Comparison with commercial treatment planning systems
Central-Axis depth dose
Comparison with commercial treatment planning systems
M. C. Lopes
IPOFG-CROC Coimbra Oncological Regional Center
L. Peralta, P. Rodrigues, A. Trindade
LIP - Lisbon
CT-simulation with a Rando phantom
Experimental data with TLD LiF dosimeter
Profile curves at 9.8 cm depth
PLATO overestimates the dose at ~ 5% level
CT images used to define the geometry:
a thorax slice from a Rando anthropomorphic phantom

4. Brachytherapy Flexibility of modeling geometries and materials
Courtesy of R. Taschereau, UCSF
Flexibility of modeling geometries and materials
Radioactive Decay Module
Low energy electromagnetic processes
Interactive facilities: visualisation, analysis, UI

5. Dosimetry Simulation of energy deposit through
Geant4 Low Energy Electromagnetic package
to obtain accurate dose distribution
Production threshold: 100 mm
2-D histogram
with energy deposit
in the plane containing the source
Analysis of the energy deposit in the phantom resulting from the simulation
Dose distribution
Isodose curves
AIDA + Anaphe
Python
for analysis
for interactivity
may be any other AIDA-compliant analysis system

6. S. Agostinelli, F. Foppiano, S. Garelli, M. Tropeano
Endocavitary brachytherapy
S. Agostinelli, F. Foppiano, S. Garelli, M. Tropeano
Role of the simulation: precise evaluation of the effects of source anisotropy
Longitudinal axis of the source
Difficult to make direct measurements
rely on simulation for better accuracy than conventional treatment planning software
Transverse axis of the source
Comparison with experimental data
validation of the software
Distance along X (mm)
Simulation
Plato
Data
Effects of source anisotropy
Distance along Z (mm)
Simulation
Plato

7. Superficial Brachytherapy
Distance along Z (mm)
Simulation
Nucletron
Data
F. Foppiano, M. Tropeano
Superficial Brachytherapy
Experimental validation:
Geant4
Nucletron data
IST data
Leipzig applicators
Code reuse:
still the same application as in the previous case
only difference: the implementation of the geometry of the applicator, derived from the same abstract class
No commercial software exists for superficial brachytherapy treatment planning!

8. Dosimetry Dosimetry Endocavitary brachytherapy
MicroSelectron-HDR source
Dosimetry
Superficial brachytherapy
Leipzig applicator

9. Interstitial brachytherapy
Dosimetry
Interstitial brachytherapy
Bebig Isoseed I-125 source
0.16 mGy =100%
Isodose curves

10. Distance away from seed
RBE enhancement of a 125I brachytherapy seed with characteristic X-rays from its constitutive materials
Goal: improve the biological effectiveness of titanium encapsulated 125I sources in permanent prostate implants by exploiting X-ray fluorescence
Distance away from seed
RBE
Titanium shell (50 µm)
Silver core (250 µm)
Percentage
++ tumors
-- healthy tissues
4.5 mm
All the seed configurations modeled and simulated with
R. Taschereau, R. Roy, J. Pouliot
Centre Hospitalier Universitaire de Québec, Dépt. de radio-oncologie, Canada
Univ. Laval, Dépt. de Physique, Canada
Univ. of California, San Francisco, Dept. of Radiation oncology, USA

11. Hadron Therapy Medical Applications
In this talk I would like to explain the reasons are bring us to work with G4 and the goals we wold like to obtain with its use.
We are the only italian prothontherapy center and actually we treated 15 patients
G.A. Pablo Cirrone
On behalf of the CATANA – GEANT4 Collaboration
Qualified Medical Physicist and PhD Student
University of Catania and Laboratori Nazionali del Sud - INFN, Italy

12. CATANA hadrontherapy facility
Modulator & Range shifter
Ligth field
Laser
Scattering system
Monitor chambers
CATANA hadrontherapy facility

13. Real hadron-therapy beam line
GEANT4 simulation

14. Hadrontherapy: comparison of physics models to data
Standard + hadronic
Standard Processes
Low Energy + hadronic
Low Energy

15. LowE e.m. + hadronic (precompound)
Beam Line Validation
LowE e.m. + hadronic (precompound)
Difference below 3% even on the peak

16. Lateral Dose Validation
Difference in penumbra = 0.5 %
Difference in FWHM = 0.5 %
Difference Max in the homogeneity region = 2 %

17. Simulation of cellular irradiation with the CENBG microbeam line using GEANT4 Sébastien Incerti representing the efforts of the Interface Physics - Biology group Centre d'Etudes Nucléaires de Bordeaux - Gradignan IN2P3/CNRS Université Bordeaux Gradignan France Nuclear Science Symposium Portland, OR, USA October 19-25th, 2003

18. GEANT4 Need for a reliable simulation tool WHY A SIMULATION TOOL ?
Technical challenge : to deliver the beam ion by ion, in air, keeping a spatial resolution compatible with irradiation at the cell level, i.e. below 10 µm
A simulation tool will help to :
understand and reduce scattering along the beam line as much as possible : collimator, diaphragm, residual beam pipe pressure…
understand and reduce scattering inside the irradiation chamber : single ion detector, beam extraction into air, cell culture layer…
predict ion transport (ray tracing) in the beam line magnetic elements
dosimetry
with high flexibility and integration.
GEANT4

19. Testing GEANT4 at the micrometer scale
Reference
Simulation of ion propagation in the CENBG microbeam line using GEANT4, S. Incerti et al., Nucl. Instr. And Meth. B 210 (2003) 92-97
Testing GEANT4 at the micrometer scale
PROTONS
ALPHAS
horizontal error bars :  5% experimental uncertainty on the foil thickness value
vertical error bars combine statistical fluctuations obtained by varying the number of incident particles in the simulation and systematic fluctuations of the FWMH values due to the  5 % error on the foil thickness ; they range from 1% to 4% for protons and from 5% to 7% for alphas.
ICRU_R49p and ICRU_R49He electronic stopping power tables used (G4hLowEnergyIonisation)
Important issue on cuts :
- Default cutValue in PhysicsList.cc : 100 µm and above
- Max step length in target foil logic volume (UserLimits) in DetectorConstruction.cc : foil thickness / 10
- low energy EM and standard packages give same results in the measured region of thickness

20. Probability to reach a given 10 µm circular surface :
Beam on target cells
AIR
AIR
VACUUM
Beam initial energy distribution :
1 mm
10 µm
In red : scattered by diaphragm
In blue :
no scattering
Beam energy distribution on target :
Probability to reach a given 10 µm circular surface :
In vacuum :
Taking into account the residual air ( mbar ) :

21. GATE, a Geant4 based simulation platform, designed for PET and SPECT
For the OpenGATE collaboration:
Steven Staelens

22. Geometry: scanners +sources
Overview
Geometry: scanners +sources
Interface with the user : scripting (macros)

23. low energy e/g extensions
Solar X-rays, e, p
Courtesy SOHO EIT
low energy e/g extensions
Cosmic rays,
jovian electrons
were triggered by astrophysics requirements
X-Ray Surveys of Planets, Asteroids and Moons
Geant3.21
ITS3.0, EGS4
Geant4
C, N, O line emissions included
Induced X-ray line emission:
indicator of target composition
(~100 mm surface layer)
Courtesy ESA Space Environment & Effects Analysis Section

24. X-ray fluorescence, PIXE
ESA Bepi Colombo mission to Mercury
Analysis of the elemental composition of Mercury crust through X-ray spectroscopy
Fluorescent spectrum of Icelandic Basalt (“Mars-like”)
Experimental data:
6.5 keV photon beam, BESSY
Courtesy of A. Owens et al., ESA
many more new features,
no time to mention them all...

25. LowE at very high energy...
Fluorescence is an important effect in the simulation of ultra-high energy cosmic ray experiments
Courtesy of Auger

26. Geant4 simulation of test-mass charging in the LISA mission
Very long base-line: 1 million km
Very high precision: < 1nm – 1pm (!)

27. Physics List EM processes (LowE) Electrons, Gammas, etc
Atomic de-excitation
Hadrons
(no hFluorescence)
Secondaries
Cuts: (250 eV), 1mm - 5mm
Kill e- outside caging

28. Underground astroparticle experiments
Gran Sasso Laboratory, Italy
unique simulation capabilities:
Courtesy of Borexino
lowE physics
fluorescence
radioactivity
neutrons
etc..
Credit: O. Cremonesi, INFN Milano

29. Boulby Mine dark matter search Prototype Simulation
Courtesy H. Araujo and A. Howard, IC London
ZEPLIN III
LXe
GXe
PMT
mirror
source
One High Energy event

30. ...and much more No time to show all applications
Very good relationship between Geant4 LowE Group and its user community
valuable feedback on applications
new user requirements to extend and improve the package
Feel free to contact us!
Many user applications become (simplified) advanced examples distributed with Geant4
to help other groups in the user community to get started