Geant4 advanced example: hadrontherapy
G.A.P. Cirrone*, G. Cutone, F. Di Rosa, G. Russo

Istituto Nazionale di Fisica Nucleare
Laboratori Nazionali del Sud
Via S. Sofia n. 64
95123 CATANIA (Italy)

*cirrone@lns.infn.it

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. 


2.Physics

The Geant4 Low Energy Electromagnetic processes are activated for electron, gamma, positron, proton antiproton particles.
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.
 

3.The processes

The sensitive detector is divided in slices; Each slice represents the collecting volume of the ionisation chamber;
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.

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.
See the README file for the details.
We are planning to move to the AIDA interface in the next release of the application.


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 
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.

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.
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).

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

  In the README of the application you will find the information about: