A General Purpose Brachytherapy Software

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2/10/2002 Geant4 Workshop CERN

• A General Purpose Brachytherapy Software
• Simulation Analysis (isodose calculation)

AIDA
Susanna Guatelli Univ. and INFN Genova CERN
Technical Student
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Brachytherapy application

• Brachytherapy is a medical therapy used for
  cancer
• treatment.
• Radioactive sources are used to deposit
  therapeutic doses
• near tumors, while preserving surrounding
  healthy tissue.

Br a medical therapy used for cancer treatment

• brachytherapy is an advanced example of Geant4.
• Its aim is to calculate the dose delivered to
  tissue
• surrounding the sources.

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• Endocavitary brachytherapy
• Uterus,vagina, lung

Ir-192

• Superficial brachytherapy
• Skin

Leipzig Applicator Ir-192
I-125

• Interstistial brachytherapy
• Prostate

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

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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)

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Design of the validation test
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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

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Results
Distribution of dose
dose distribution
Spectrum of the gammas delivered by the source

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

Energy delivered in the plane containing the
source
More Studies are required !
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Dose distribution TG 43 protocol, experimental
data (S. Paolo Hospital, Savona), G4-LowE
? Protocol ? Data (SV) ? G4-LowE
G4 Standard and LowE agree
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User requirementsof brachytherapy example

• The aim of the software is to calculate the
  distribution of dose of brachytherapeutic sources
  in 3D in the phantom and the
• isodose 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
  (its 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

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Design
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(No Transcript)
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Mainfeaturesof the implementationof the
brachytheapyexample
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• Definition of the brachytherapic source

Abstract Factory
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• 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
• its possible to
  interface the software to CT
• Physical Processes
• Low Energy for gamma
• Standard for e
• Low Energy/Standard for
  e-

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• 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

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Results
Bebig Isoseed I-125
Interstitial brachytherapy
Superficial brachytherapy
Leipzig applicator
Endocavitary brachytherapy
microSelectron-HDR
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Leipzig applicator
Dose in a phantom of soft tissue
Work in Progress!
Isodose voxels
50 MeV
100 50 10
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Collaborations
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
And Geant4 collaboration, AIDA/Anaphe
group