Implementation of a New Monte Carlo Simulation Tool for the Development of a Proton Therapy Beam Line and Verification of the related Dose Distributions G.A. Pablo Cirrone On behalf of the CATANA Collaboration Qualified Medical Physicist and PhD Student University of Catania and Laboratori Nazionali del Sud - INFN, Italy

What is the hadron-therapy? Use of ions for the radiotherapeutic treatment of tumours

In Catania we developed a facility CATANA for the treatment of ocular tumours with proton beams of 62 AMeV The Laboratori Nazionali del Sud

LNS Superconducting Cyclotron is the unique machine in in Italy and South Europe used for protontherapy Treatment of the choroidal and iris melanoma In Italy about 300 new cases for year

Scattering system Modulator & Range shifter Monitor chambers Ligth field Laser

Experimental Data from our Facility

Why to start a Simulation Work ? Therapy with hadrons still represents a pioneering thecnique Today the development of a hadron-therapy facility requires a long experimental work due to the lack of SIMULATION TOOLS Our work is inserted in the more general medical-physics GEANT4 activity and represents just a different application of a more general approach in the medical-physics field

So we start our simulation work using GEANT4: To simulate our complete beam line with all its elements and To riproduce all the dose distributions To validate the treatment planning systems It’s impossible to conceive a modern detector w/o simulation Rossi and Greisen 1941, Rev. Mod. Phys. 13:240 Why to start a Simulation Work ?

Our GEANT4 Application: hadronTherapy.cc Complete simulation of CATANA hadron-therapy beam line with two dosemeters Depth Dose Distribution in Water ( Bragg curve ): Markus type ionization chamber; Lateral Dose Distribution: Radiochromic film;

DETECTORS USED FOR DOSE DISTRIBUTION MEASUREMENTS DEPTH DOSE DISTRIBUTION Markus Ionization chamber 2 mm Sensible Volume = 0.05 cm 3 LATERAL DOSE DISTRIBUTION GAF Chromic Film Resolution 100  m for DDP and 200  m for LDP Markus Chamber layoutIrradiated GAF Chromic

Water box with ionisation chamber Water box + detector for Bragg curve as simulated Bragg Curve Reconstruction

Validation of Simulated Detector (From a Software point view) Comparison with NIST ranges data

Beam Line Simulation: Scattering system Permits to obtain an homogeneus lateral dose distribution at isocenter DOUBLE SCATTERER FOIL WITH CENTRAL STOPPER 15  m + 25  m + 7 mm thick copper beam stopper

Real hadron-therapy beam line GEANT4 simulation Each element of the line can be modified (in shape, material and position) and other kinds of dosemeters can be easily inserted

Physics models Standard Processes Standard + hadronic Low Energy Low Energy + hadronic

“beam’s picture” at isocenter

Low Energy + hadronic package Differences below 3% also in the peak region Beam Line Validation

Ranges comparison with experimental data for water and copper WATER ALLUMINUM

Difference in penumbra = 0.5 % Difference in FWHM = 0.5 % Difference Max in the homogeneity region = 2 % Beam Line Validation

Isodoses Curve Comparison Collimator Diameter = 20 mm Collimator Diameter = 25 mm Difference below 5 % Difference below 8 %

 Penumbra increases of 34%  Energy spread increases of 83% Use of Simulation to Obtain Not-Easy Informations profiles along beam axis  Knowledge of proton energy spectrum

Lower Energy Component for protons We demonstrated this is due to the particular design of final collimator Use of Simulation to Obtain Not-Easy Informations

Future developments Simulation of the Modulator Wheel to Obtain the Therapeutical Spread Out Bragg Peak tumour (Work in progress)

Future developments Insertion of DICOM images (i.e. Like those from a Computed Tomography Examination) More realistic doses distribuition Transfer of the application to the GRID Velocity comparable but quality superior respect with the conventional (analytical based) treatment planning systems actually in use Development of new statistical tools for ISODOSES COMPARISON between experimental data and fromTPS data

Future developments The application will be inserted soon (we hope in the first release of 2004) in the public distribution of the GEANT4 tool as advanced example We imagine our application can be used from other users for the design and development of new hadron-therapy facility and for the test of the treatment planning systems