A General Purpose

Brachytherapy Software

Simulation + Analysis (isodose calculation)

2/10/2002 Geant4 Workshop CERN

Susanna Guatelli Univ. and INFN GenovaCERN Technical Student

AIDA

Brachytherapy applicationBrachytherapy application

Br a medical therapy used for cancer treatment

•Brachytherapy is a medical therapy used for cancer treatment.

•Radioactive sources are used to deposit therapeutic doses near tumors, while preserving surrounding healthy tissue.

•brachytherapy is an advanced example of Geant4.

•Its aim is to calculate the dose delivered to tissue surrounding the sources.

•Endocavitary brachytherapy Uterus,vagina, lung

•Superficial brachytherapy Skin

•Interstistial brachytherapy Prostate

3 m m ste e l c a b le

5.0 m m

0.6 m m

3.5 m m

1.1 m m

Ac tive Ir-192 C o re

Ir-192

LeipzigApplicatorIr-192

I-125

The brachytherapy example calculates dose in the phantom for all these techniques

Validation of the software•Simulation of the dose distribution of the interstitial source Isoseed I-125

•Comparison with experimental data measurements of the distribution of dose with films (performed at the Institute of Medical Physics of San Paolo Hospital, Savona, Italy) •Comparison with the actual protocol about interstitial seeds (TG43)

User Requirements

• Model of a simple geometry• Physical processes for e-,e+, gamma• Primary particles• Track of the particles• Visualization of the experimental setup• Calculation of the energy deposit in the plane containing the source• Analysis and store of the results (histograms)

Design of the validation test

Implementation•The spectrum of primary particles is implemented•The phantom is a box filled with water•The geometry of the source is implemented•Low Energy processes are implemented for gamma •Standard processes for e+•Low Energy or Standard for e-•Cut in range 0.1 mm•Detector is the phantom: divided in voxels (dimension 1mm)•Visualization of the geometry involved•1D histogram filled with the initial energy of the gamma (check!)•2D histogram filled with the energy deposit in the plane containing the source in relation to the position (voxel) in the plane itself

Results

Spectrum of the gammas delivered

by the source

Energy delivered

in the plane containingthe source

Distributionof dosedose distribution

•Standard and Low Energy Packages for e-give the same results•No agreement with the protocol•Agreement with experimental measurements

More Studies are required !

Dose distribution: TG 43 protocol, experimental data (S. Paolo Hospital, Savona), G4-LowE

G4 Standard and LowE agreeG4 Standard and LowE agree

Protocol

Data (SV)

G4-LowE

User requirementsof brachytherapy example

•The aim of the software is to calculate the distribution of dosedistribution of dose of brachytherapeutic sources in 3D in the phantom and the isodose curvesisodose curves in planes. •The user shall be able to define the type of the brachytherapic source•The user shall be able to define the materials of the phantom•The software can be interfaced with CT images (it’s possible to define the materials of the real geometry involved)•Visualisation of the experimental environment•Store of the data

Software for all the kinds of brachytherapy

Design

S. Guatelli, M.G Pia, INFN Genova

Mainfeatures

of the implementationof the

brachytheapyexample

•Definition of the brachytherapic source

Abstract Factory

•Geometry: 1) the user can choose the absorber material of the phantom 2)thanks to the parameterisation of the phantom it is possible to define different materials for each elementary volume (voxels) 3) thanks to the parameterisation and the introduction of a map associating geometry and materials it’s possible to interface the software to CT•Physical Processes: Low Energy for gamma Standard for e+ Low Energy/Standard for e-

•Primary particles: 1)spectrum of the gamma delivered by the radioactive core 2)the direction of emission is random•Detector: phantom: divided in voxels ( box, dimension 1mm) •Particles: 1)all the particles ( primary and secondary) are tracked 2)cut in range 0.1 mm•Visualization of the experimental environment•Ntuple: store of the energy deposit in all the phantom•1D histogram: spectrum of gamma delivered by the radioactive core•Calculation of the isodose lines

ResultsBebig Isoseed I-125

microSelectron-HDR

Leipzig applicator

Endocavitary brachytherapy

Interstitial brachytherapy

Superficial brachytherapy

Leipzig applicatorDose in a phantom of soft tissue

Work inProgress!

50 MeV 100 %50 %10 %

Isodose voxels

nt4

INFN Genova M.G. Pia

CERN A. Pfeiffer

San Paolo Hospital, Savona G. Ghiso

National Institute for Cancer Research – IST, Genova A. Agostinelli, F. Foppiano, S. Garelli, M. Tropeano

, R.aaanMarti

Collaborations

And Geant4 collaboration, AIDA/Anaphe group