last modified G.A.P. Cirrone 29/06/2004
Introduction
Hadrontherapy is an advanced
radiotherapic technique to treat radioresistant and inoperable tumors using
particles like protons and ions. Main Features of the Hadrontherapy example
1.General
features of the application
The application give the possibility
to simulate a typical hadron therapy treatment beam line (including all its
elements) and to calculate
the proton/ion dose distribution curves.
The Geant4 Low Energy
Electromagnetic processes
are activated for electron, gamma, positron, proton antiproton particles. 3.The processes
The sensitive detector
is divided in slices; Each slice represents the collecting volume of the
ionisation chamber;
4. The data output Actually
three simple ascii files are produced by a simulation run in order to get the
information on the dose distributions. The Hadrontherapy example development
The GEANT4 Hadrontherapy advanced
example allows to to the user to simulate a complete (and generic) proton
therapy beam line furnishing him, also the possibility to test its elements and
to generate all the dose distribution curves of the involved beams. It could be
an important instrument for all the centres are developing a new proton therapy
facility, if they want to design and optimise their the transport beam line,
check the dose distributions before the experimental measurements and, finally,
test their, analytical based, treatment planning systems. Using
such application the user will be able to adapt the simulation to his/her
specific beam line inserting in a simple way all the typical elements (range
shifter, modulator wheel, collimators (see Figures 1 and 2), etc.) of his/her
beam line. Each element can be changed in position, composition, dimension and
all this can be done without enter in the C++ code, and hence without any
compilation, but just defining an input file.
Figure
1. Real and simulated final collimator used in a typical eye proton therapy
treatment.
Figure
2. Real and simulate modulator wheel. The modulator permits the energy
modulation of the proton beam energy and, hence, to
Figure
3. The real proton therapy beam line installe at Laboratori Nazionali del Sud (INFN)
in Catania (left picture); the graphic output of the advanced example developed
for the simulation of the same beam line (rigth) The
high flexibility of Geant4, based on the Object Oriented technology, make this
possible in a very simple way. The Hadrontherapy advanced
example follows the Unified Software Development Process; in this way it's
possible to guarantee the rogorousity of the product.
Figure
4. Comparison beetween two Bragg peaks obtained using the example (and using two
different Geant4 physics configurations) and the experimental data.
Figure
5. Lateral dose distribution after a simulation run of 1 milions of protons at
the end of the beam line (where the patient is positioned during the treatment)
How to run the application
2.Physics
Alternatively it is possible to
use the Standard Electromagnetic package for the same particle beams.
The LHEP and HEP hadronic models are activated.
Cut per region feature is activated permitting to set the a more accurate
simulation resolution inside the sensitive detector.
The total energy deposit in each slice is collected at
the end of the run and it is associated with the center of the slice itself.
See the README file for the details.
We are planning to move to the AIDA interface in the next release of the
application.
obtain the Spread Out Bragg Peak.
Figure 3 shows a particular application of the example: the simulation of the
eye-proton therapy beam line installed at Laboratori Nazionali del Sud of
Istituto Nazionale di Fisica Nucleare in Catania, (Sicily) Italy.
The requested functionalities
are listed in the User Requirements
.
The design is shown in Hadrontherapy
example design .
Validation tests have been
performed on the basis of the exerimental data acquired at the CATANA proton
therapy facility.
These tests regard mainly the
comparison of the simulated depth (Bragg Peak) and lateral dose distribution
curves and proton beam range in different material with the experimental ones.
Experimental data are acquired using some typival dosimetric systems emplyed in
the proton therapy practice: a Markus, air-free ionisation chamber for the depth
dose reconstruction and the GafChromic films for the lateral dose distribution
measurements.
Figure 4 shows the comparison beetween
the Bragg peak output of Hadrontherapy obtained activating the Low Energy
electromagnetic models and than adding the Hadronic Pre Compound model (to tke
into account the nuclear interactions in the dose deposition) and a set of
experimental data. Figure 5 shows a three dimensional lateral distribution
picture of the proton at the end of the beam line (where patient tipically sit).
In the README of
the application you will find the information about: