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Geant4 - Hadrontherapy example
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README
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This example is developed by G.A.Pablo Cirrone, Giorgio Russo and
Francesco Di Rosa of the Laboratori Nazionali del Sud - Istituto Nazionale
di Fisica Nucleare, Via S. Sofia, 44 Catania, Sicily, Italy (www.lns.infn.it)
The authors are supported by Laboratori Nazionali del Sud, Catania and by the
Dipartimento di Fisica of Catania University, Catania.
The authors wish to thank Susanna Guatelli and Maria Grazia Pia for
their support in the realization of the sensitive detector and
Harald Paganetti (from NPTC, Massachussets (US)) for the
help in the realization of the movement of the modulator wheel.
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----> INTRODUCTION.
The hadrontherapy example simulates a hadron therapy beam line.
In particular the example models the specific proton therapy beam line
installed at Laboratori Nazionali del Sud (INFN) in Catania, Sicily (Italy).
For more information on the proton therapy center of Catania
or/and proton/hadron therapy in general, please visit the
pages:
> www.lns.infn.it/~catana
----> GEOMETRY SET-UP.
The elements simulated are:
1. A scattering system, to spread geometrically the beam;
2. A system of collimators, to avoid the scattering radiation;
3. A modulation system that spreads the beam in energy and
produces the so-called spread out bragg peak;
It is constituted by a rotating wheel of different thichnesses.
The wheel rotates around is axis (parallel to the proton
beam axis) and its movement can be obtained by means of a
messenger between runs.
4. A set of monitor chambers (special transmission ionisation
chambers used to control hadron flux during the irradiation);
5. A "nozzle" and a final collimator defining the final shape
of the beam before reaching the patient.
6. A water phantom: it is a box of water inside of which the
dosimeter is placed; the dosimeter performs the measurements of
dose distributions.
The use of the water phantom is required by the international protocol
on the measure of dose in the case of proton and ion beams (IAEA 398, 2000).
7. A "Markus" ionisation chamber, to reconstruct the depth dose distribution
(Bragg curve).
8. A radiographic film, to evaluate the beam lateral dose
distribution, registering the spatial distribution of the
primary particles
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----> 1.EXPERIMENTAL SET-UP.
The application fully simulates the proton therapy beam line
installed at Laboratori Nazionali del Sud. Inside the water
phantom (placed at the end of the proton beam line) the Markus ionisation
chamber and a radiographic film are located; these elements permit the
reconstruction of the Bragg curve (registered on the file BraggPeak.out)
and of the lateral and energy distribution of the particles (registered
on the files energyDistribution.out and angularDistribution.out). Please
see later for the description of the produced files.
The Markus chamber is realized by means of a water cylinder (placed inside
the water phantom) with its main axis coincident with proton beam axis.
The cylinder is divided in slices and the energy deposit in each slide is
collected at the end of each run. The default thickness of the slices
is 2 micron.
The radiographic film is simulated by a plane. It is located, by default,
at the entrance window of the water phantom (the isocenter point) and
its thickness is 1. mm.
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----> 2.SET-UP
- a standard Geant4 example GNUmakefile is provided
setup with:
compiler = gcc-3.2.3
G4SYSTEM = linux-g++
The following section reports the necessary environment variables
necessary for the run of Hadrontherapy.
----> 2.1 ENVIROMENT VARIABLES
- G4SYSTEM = Linux-g++
- G4INSTALL points to the installation directory of GEANT4;
- G4LIB point to the compiled libraries of GEANT4;
- G4WORKDIR points to the work directory;
- CLHEP_BASE_DIR points to the installation directory of CHLEP;
- G4LEVELGAMMADATA points to the photoevaporation library;
- NeutronHPCrossSections points to the neutron data files;
- G4RADIOACTIVEDATA points to the libraries for radio-active decay
hadronic processes;
- G4LEDATA points to the low energy electromagnetic libraries
- LD_LIBRARY_PATH = $CLHEP_BASE_DIR/lib
----> 2.2 VISUALISATION
The user can visualise the experimental set-up with OpenGL, DAWN and vrml
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----> 3. HOW TO RUN THE EXAMPLE.
In interactive mode:
> $G4WORDIR/bin/Linux-g++/Hadrontherapy
The defaultMacro.mac is executed
The primary particle beam parameter are:
Radiation: proton beam;
Energy distribution: gaussian;
Mean energy: 63.4 MeV;
Energy spread: 300 keV;
Beam spot size: 1 mm;
Beam angular spread: 0.057 deg;
Cut per region feature permits to set different cut in different regions.
In this example it is sufficient to set a small cut inside the dosemeter
(where the information of dose distribution is collected).
Default values are:
cut = 10 mm along the beam line;
cut = 0.2 mm inside the dosemeter;
The modulator wheel can be rotated via the messenger:
Idle>/modulator/angle/modAngle xx deg
It is sufficient to rotate the modulator from 0 deg (default position)
to 45 deg using 1 deg steps to obtain a Spread Out Bragg Peak (SOBP).
Modulator wheel can be omitted setting its material air.
run $G4WORKDIR/bin/Linux-g++/Hadrontherapy visualisation.mac
to visualise the experimental set-up with OpenGL
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----> 4. PHYSICS
Electromagnetic and hadronic processes are modeled.
The LowEnergy package is used to model the electromagnetic processes
of all the particles involved in the experimental set-up.
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----> 5. SIMULATION OUTPUT
The output is in ASCII file format:
1.) BraggPeak.out: a two columns file.
The first column represent depth in water (mm), the second contains the energy
deposit (MeV).
2.) energyDistribution.out: a two columns file.
The first column contains the energy deposit (in MeV) by primary particles
in the plane (radiographic film) positioned at isocenter.
The second column indicates the number of the primary particle
responsible for the energy deposit.
3.) angularDistribution.out: a three columns file.
It contains the coordinates in millimeters (x, y, z) of a primary
particle interacting with the plane representing the radiographic film.
x direction is along the beam direction,
y and z directions are orthogonal to the beam direction.
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----> 6. FUTURE PLANS
Next planned improvements will be:
** Use of AIDA and PI analysis tools to store the results of the
simulation in .xml/.hbk files
** Addition of messengers to interactively change position, dimension
and composition of all the beam line elements and of the
simulated dosimetric systems and to change cut values;
** Addition of messenger to change energy, energy spread,
beam spot size and angular divergence of the proton beam;
** Realization of the read-out-geometry: this will permit to collect
the energy deposit inside a voxelized three dimensional volume.
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for comments, advices, doubts and questions please contact:
cirrone@lns.infn.it, giorgiorusso@lns.infn.it
last modified: Susanna Guatelli, 28/5/2004
Gabriele Cosmo