Low Energy Electromagnetic Physics
PART II
Maria Grazia Pia
INFN Genova
[email protected]
on behalf of the Low Energy Electromagnetic Working Group
Geant4 Workshop
Helsinki, 30-31 October 2003
http://www.ge.infn.it/geant4/training/
Maria Grazia Pia, INFN Genova
1
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
Maria Grazia Pia, INFN Genova
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Comparison with commercial
treatment planning systems
Central-Axis depth dose
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
CT images used to
define the geometry:
PLATO overestimates
the dose at ~ 5% level
a thorax slice from a
Rando
anthropomorphic
phantom
Maria Grazia Pia, INFN Genova
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Brachytherapy
Courtesy of R. Taschereau, UCSF
Flexibility of modeling geometries and materials
Radioactive Decay Module
Low energy electromagnetic processes
Interactive facilities: visualisation, analysis, UI
Maria Grazia Pia, INFN Genova
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Dosimetry
Simulation of energy deposit through
Geant4 Low Energy Electromagnetic package
to obtain accurate dose distribution
2-D histogram
with energy deposit
in the plane containing
the source
Production threshold: 100 mm
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
Maria Grazia Pia, INFN Genova
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Endocavitary brachytherapy
S. Agostinelli, F. Foppiano, S. Garelli, M. Tropeano
40
Cut 0.1mm
30
200%
150%
100%
75%
50%
25%
Distanza lungo Z (mm)
20
10
0
-10
-20
-30
Role of the simulation: precise evaluation
of the effects of source anisotropy
-40
-40
-30
-20
-10
0
10
20
30
Longitudinal axis of the source
40
Distanza lungo X (mm)
Transverse axis of the source
Difficult to make direct measurements
rely on simulation for better accuracy than
Comparison with experimental data
 validation of the software
conventional treatment planning software
Simulation
Simulazioni
Plato
Plato
Data
Misure
2,5
Effects
of source anisotropy
2,5
Simulazioni
Simulation
Plato
Plato
2,0
Dose %
Dose %
2,0
1,5
1,0
1,5
1,0
0,5
0,5
0,0
0,0
-40
-30
-20
-10
0
10
20
Distanza
lungo X (mm)
Maria Grazia Pia,
INFN Genova
Distance
along X (mm)
30
40
-40
-30
-20
-10
0
10
Distanza lungo Z (mm)
20
6
Distance along
Z (mm)
30
40
Simulation
Simulazione
Nucletron
Nucletron
Data
Misure
1,2
Superficial Brachytherapy
1,0
F. Foppiano, M. Tropeano
Experimental validation:
Geant4
Nucletron data
IST data
Dose %
0,8
0,6
0,4
0,2
Leipzig
applicators
0,0
0
10
20
30
Distance
along
Z (mm)
Distanza
lungo
Z (mm)
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!
Maria Grazia Pia, INFN Genova
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40
50
Dosimetry
Endocavitary brachytherapy
MicroSelectron-HDR source
Dosimetry
Superficial brachytherapy
Leipzig applicator
Maria Grazia Pia, INFN Genova
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Dosimetry
Interstitial brachytherapy
Bebig Isoseed I-125 source
0.16 mGy =100%
Isodose curves
Maria Grazia Pia, INFN Genova
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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)
1.08
1.08
Mo- Y
1.06
1.06
M200
M200
1.04
1.04
1.02
1.02
Silver core (250 µm)
++ tumors
11
00
11
-- healthy tissues
22
33
44
55
4.5 mm
Distance away from seed
All the seed configurations
modeled and simulated with
Maria Grazia Pia, INFN Genova
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. of10Radiation oncology, USA
Hadron Therapy Medical
Applications
G.A. Pablo Cirrone
On behalf of the CATANA – GEANT4 Collaboration
Qualified Medical Physicist and PhD Student
11
University of Catania and Laboratori Nazionali del Sud
- INFN, Italy
Maria Grazia Pia, INFN Genova
Modulator &
Range shifter
Ligth
field
Laser
Maria Grazia Pia, INFN Genova
Scattering
system
Monitor
chambers
CATANA hadrontherapy facility
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Real hadron-therapy
beam line
GEANT4 simulation
Maria Grazia Pia, INFN Genova
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Hadrontherapy: comparison of physics models to data
Standard
Processes
Standard +
hadronic
Low Energy
Low Energy
+ hadronic
Maria Grazia Pia, INFN Genova
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Beam Line Validation
LowE e.m. +
hadronic (precompound)
Difference below 3%
even on the peak
Maria Grazia Pia, INFN Genova
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Lateral Dose Validation
Difference in penumbra = 0.5 %
Difference in FWHM = 0.5 %
Difference Max in the homogeneity region = 2 %
Maria Grazia Pia, INFN Genova
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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 : [email protected]
Nuclear Science Symposium
Portland, OR, USA
October 19-25th, 2003
Maria Grazia Pia, INFN Genova
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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.
Maria Grazia Pia, INFN Genova
GEANT4
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Reference
Testing GEANT4 at the micrometer scale
Simulation of ion propagation in the CENBG microbeam line using
GEANT4,
S. Incerti et al., Nucl. Instr. And Meth. B 210 (2003) 92-97
ALPHAS
PROTONS
•
•
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
Maria Grazia Pia, INFN Genova
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Beam on target cells
AIR
AIR
• Beam initial energy distribution :
VACUUM
1 mm
10 µm
T ± s T = 3.00 MeV ± 0.06 keV
In red :
scattered by
• Beam energy distribution on target :
diaphragm
T ± s T = 2.37 ± 0.01 MeV
In blue :
no scattering
pexp » 80 - 90%
Probability to reach a given 10 µm circular surface :
• In vacuum : pa ± s p = ( 99.41 ± 0.05)%
• Taking into account the residual air ( 5.10-6 mbar ) :pa ± s p = (70.5 ± 0.8)%
a
a
Maria Grazia Pia, INFN Genova
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GATE, a Geant4 based simulation
platform, designed for PET and
SPECT
For the OpenGATE collaboration:
Steven Staelens
Maria Grazia Pia, INFN Genova
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Overview
Geometry:
+sources
Interface
with the user scanners
: scripting (macros)
Maria Grazia Pia, INFN Genova
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low energy e/g extensions
Cosmic rays,
jovian electrons
were triggered by astrophysics requirements
X-Ray Surveys of Planets, Asteroids and Moons
Solar X-rays, e, p
Courtesy SOHO EIT
Geant3.21
Induced X-ray line emission:
indicator of target composition
(~100 mm surface layer)
ITS3.0, EGS4
Geant4
C, N, O line emissions included
Maria Grazia Pia, INFN Genova
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Courtesy ESA Space Environment
& Effects Analysis Section
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
Maria Grazia Pia, INFN Genova
many more new features,
no 24
time to mention them all...
LowE at very high energy...
Fluorescence is an
important effect in the
simulation of ultra-high
energy cosmic ray
experiments
Courtesy of Auger
Maria Grazia Pia, INFN Genova
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Geant4 simulation
of test-mass charging in the LISA mission
Very long base-line: 1 million km
Very high precision: < 1nm – 1pm (!)
Maria Grazia Pia, INFN Genova
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Physics List
EM processes (LowE)
Electrons, Gammas, etc
Atomic de-excitation
Hadrons
(no hFluorescence)
Secondaries
Cuts: (250 eV), 1mm - 5mm
Kill e- outside caging
Maria Grazia Pia, INFN Genova
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Underground astroparticle experiments
Courtesy of Borexino
Gran Sasso Laboratory, Italy
unique simulation
capabilities:
lowE physics
fluorescence
radioactivity
neutrons
etc..
Maria Grazia Pia, INFN Genova
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Credit: O. Cremonesi, INFN Milano
Boulby Mine dark matter
search Prototype Simulation
Courtesy H. Araujo and A. Howard,
IC London
ZEPLIN III
One High Energy event
mirror
LXe
GXe
PMT
Maria Grazia Pia, INFN Genova
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source
...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
Maria Grazia Pia, INFN Genova
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