Low Energy Electromagnetic Physics PART II

1
Low Energy Electromagnetic Physics PART II

• Maria Grazia Pia
• INFN Genova
• Maria.Grazia.Pia_at_cern.ch
• on behalf of the Low Energy Electromagnetic
  Working Group
• Geant4 Workshop
• Helsinki, 30-31 October 2003

http//www.ge.infn.it/geant4/training/
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
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
CT images used to define the geometry a thorax
slice from a Rando anthropomorphic phantom
4
Brachytherapy
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
AIDA Anaphe
Python
for analysis
for interactivity
may be any other AIDA-compliant analysis system
6
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

Effects of source anisotropy
7
Experimental validation Geant4 Nucletron
data IST data

• 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 Endocavitary brachytherapy
MicroSelectron-HDR source
Dosimetry Superficial brachytherapy
Leipzig applicator
9
Dosimetry Interstitial brachytherapy
Bebig Isoseed I-125 source
10
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
Titanium shell (50 µm)
Silver core (250 µm)
Percentage
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
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
13
Real hadron-therapy beam line
14
Hadrontherapy comparison of physics models to
data
Standard hadronic
Standard Processes
Low Energy hadronic
Low Energy
15
Beam Line Validation
LowE e.m. hadronic (precompound)
Difference below 3 even on the peak
16
Lateral Dose Validation
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 1 33175 Gradignan
France Email incerti_at_cenbg.in2p3.frNuclear
Science SymposiumPortland, OR, USAOctober
19-25th, 2003
18
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.

19
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

• 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
Beam on target cells
VACUUM
AIR
AIR

• Beam initial energy distribution

1 mm
10 µm
In red scattered bydiaphragm
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 ( 5.10-6
  mbar )

21
GATE, a Geant4 based simulation platform,
designed for PET and SPECT
For the OpenGATE collaboration
Steven Staelens
22
Geometry scanners sources
Overview
23
low energy e/g extensions
Cosmic rays, jovian electrons
were triggered by astrophysics requirements
X-Ray Surveys of Planets, Asteroids and Moons
Induced X-ray line emission indicator of target
composition (100 mm surface layer)
Courtesy ESA Space Environment Effects Analysis
Section
24
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 simulationof test-mass charging in the
LISA mission
     

• Very long base-line 1 million km
• Very high precision lt 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

• lowE physics
• fluorescence
• radioactivity
• neutrons
• etc..

29
Boulby Mine dark matter search Prototype
Simulation
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