Hadron Therapy Medical Applications
G.A. Pablo Cirrone
On behalf of the CATANA – GEANT4 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 radiotherapeutictreatment of tumours
0
20
40
60
80
100
120
0 5 10 15 20 25 30depth cm of water
% d
ose
resp
onse
8 MV X-rays200 MeV protons20 MeV electronscobalt 60
So we can answare to the question:Why clinical proton beams?
• penetration depth is well-defined and adjustable
• most energy at end-of -range
• protons travel in straight lines
• dose to normal tissue minimised
• no dose beyond target
PROTONS PERMIT TO DELIVER AN HIGH DOSE TOTHE TUMOUR SPARING THE SOURRONDING TISSUES
In Catania we developed a facility
CATANAfor the treatment ofocular tumours with proton beams of 62
AMeV
LNSSuperconducting Cyclotron is the
unique machine in inItaly and South Europe used for protontherapy
Treatment of thechoroidal melanoma
In Italy about 300 new cases for year
Laboratori Nazionali del Sud –INFN Catania, Italy
CyclotronLocation
Proton BeamTreatment
Room Location
•0 ° respect the switching magnet
•80 meter after extraction
•3 m proton beam line
LAYOUT OF LNSPRESENT TREATMENT ROOM
Scattering system
Modulator &Range shifter
Monitorchambers
Ligth field
Laser
A brief description of the treatment
•The surgical phase
•The Treatment planning phase
•The verification phase
•The treatment phase
Surgical Phase (Tantalum clips insertions)
CLIPS: characterizeposition and size oftumor volume
two X-Rays tubes for the visualization of the clips
Treatment Planning System
EYEPLANEYEPLAN
In origin developed by Michael Goiten eTom Miller ( Massachussetts General
Hospital) e ora mainteined by Martin Sheen(Clatterbridge Center for Oncology) e Charle
Perrett (PSI)
Treatment Planning System Output
Isodoses curves for different planes
θ
Fixation Light
φ
θ Polar Angleφ Azimutal Angle
Isocenter
Fixation Point
Patiens look at the fixation lightduring the treatment
PROTON BEAM
Patient Distribution by Origin Region
20
6
5
5
5
4
6
20
2
1
1
N.B Total number of patients : 52
Hadron-Therapy Center of Sicilian Region
Project approved on March, 7 2003
DETECTORS USED FOR DOSE DISTRIBUTION MEASUREMENTS
DEPTH DOSE DISTRIBUTION LATERAL DOSE DISTRIBUTION
•Markus Ionization chamber •GAF Chromic Film
2 mm
Sensible Volume = 0.05 cm3
Markus Chamber layout Irradiated GAF Chromic
Resolution 100 µm for DDP and 200 µm for LDP
Experimental ‘PURE’ Bragg curve
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25 30 35
Depth in water (mm)
Rel
ativ
e Io
nizz
atio
n (%
)
Markus Ionization Chamber
31.150.503.194.6830.14MARKUS
Practical Range(d10%, ICRU 59)
Distal -dose
falloffd80%-20%
F.W.H.M.PEAK –PLATEAU
RATIO
PEAK DEAPTH
DETECTOR
Experimental ‘modulated’ Bragg curve
0
20
40
60
80
100
120
0 10 20 30 40Depth in water (mm)
Rel
ativ
e D
ose
(%)
95%
R90%
80%
20%
Modulated region
Experimental Lateral Dose Distribution
0
20
40
60
80
100
-20 -15 -10 -5 0 5 10 15 20
Distance from axis [ mm ]
Sig
nal [
% ]
Radiochromic Film
R 90%-50% Ps [mm]
Pd [mm]
Simmetry [%]
Homogeneity at 95% level
[mm] LNS 0.92 0.8 1 2.4 21 CCO 0.93 0.75 0.75 2.6 23
Why to start a Simulation Work ?
Therapy with hadrons still represents apioneering thecnique
Today the development of ahadron-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 moregeneral approach in the medical-physics field
Why to start a Simulation Work ?
This work concerns mainly:
Design and optimization of thetansport beam line elements:
Test of the elements
Test of the detectorsReconstruction of the dosedistributions:
To measure dose distribution also in difficult experimental region
To verify the radiotherapytreatment planning systems
Why to start a Simulation Work ?
So we start our simulation work using GEANT4:
•To simulate our complete beam linewith all its elements and
•To riproduce all the dose distributions
It’s impossible to conceive a modern detector w/o simulation
Rossi and Greisen 1941, Rev. Mod. Phys. 13:240
Why GEANT4 for a Medical Application?
User support from experts
Free and “Transparent”code
Transparency of physics Use of evaluated data libraries
Independent validationby a large user community worldwide Specific facilities
controlled by a friendly UI
Our GEANT4 Application:
hadronTherapy.cc
Complete simulation of CATANAhadron-therapy beam line with two dosemeters
• Depth Dose Distribution in Water ( Bragg curve ):Markus type ionization chamber;
• Lateral Dose Distribution:Radiochromic film;
Each element of the line can be modified (in shape, material and position) and other kinds of dosemeters can be easily
inserted
Design of hadronTherapy Application
hadronTherapy design
Water box + detectorfor Bragg curve as simulated
Bragg Curve Reconstruction
Water box with ionisation chamber
Bragg Curve Reconstruction
Detector is simulated with20 K air cylindrical slices, 200 µm thick to reproduce experimental Markus chamber responce
Energy deposited ineach slice is collected
We calculated range values for the detectorsimulation validation from Bragg curve
Validation of detector for the Bragg curve reconstruction Comparison with ICRU/NIST data
Beam Line elements simulation
• Scattering system
• Collimators system
• Monitor chambers
• Final and Patient’s collimator
Scattering system
DOUBLE SCATTERER FOIL WITH CENTRAL STOPPER15 µm + 25 µm + 7 mm thick copper beam stopper
Permits to obtain an homogeneus lateraldose distribution at isocenter
Collimators system
Monitor chambers system
GEANT4 simulation
Real hadron-therapy beam line
Primary Beam Characteristic
On the basis of experimentals Bragg curves we were able to set the characteristics of the
primary beam
•Initial Energy
•Energy Spread
•Spatial Distribution
•Momentum Distribution
Physics models
StandardProcesses
Standard +hadronic
Low Energy Low Energy+ hadronic
“beam’s picture” at isocenter
Differenze al di sotto del 3% anche sul picco
Beam Line Validation
Package basse energie+
fisica adronica
WATER
Beam Line Validation
ALLUMINUMRanges comparison with experimental datafor water and copper
Lateral Dose Validation
Difference in penumbra = 0.5 %
Difference in FWHM = 0.5 %
Difference Max in the homogeneity region = 2 %
Isodoses Comparison (qualitative comparison)
Dose level at 80% and 60 % of the maximum
Red: radiochromic film
Blue: GEANT4
Isodoses Comparison (a more quantitative approach)
Difference of the areas for differtent isodose levels between GEANT4 and Experimental Data
Collimator Diameter = 20 mm
Collimator Diameter = 25 mm
Difference below 5 %
Difference below 8 %
Future developments
Simulation of the Modulator Wheel to Obtain the Therapeutical Spread OutBragg Peak
0
10
20
30
40
50
60
70
80
90
100
110
0 5 10 15 20 25 30 35Depth in water [mm]
Nor
mal
ized
Dep
th D
ose
Dis
trib
utio
n
tumour
(Work in progress)
Future developments
Insertion of DICOM images (i.e. Like those from a Computed Tomography Examination)
More realistic doses distribuition
Development of new statistical toolsfor ISODOSES COMPARISON between experimental data and fromTPS data
Transfer of the application to the GRID
Velocity comparable but quality superior respect with the conventional (analytical based) treatment planning systems actually in use
Future developments
The application will be inserted soon(we hope in the first release of 2004) in the publicdistribution 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
Thank you
Maria Grazia Pia
and
Susanna Guatelli
INFN Section of Genova (Italy)
For their scientific help and practical support they give me during the period I spent at CERN
in the study of GEANT4 code