Technological Transfer

1
Technological Transfer from HEP to Medical
Physics How precise Brachytherapy MonteCarlo
simulations can be applied in Clinics Reality

• Brachytherapy is a medical therapy used for
  cancer treatment
• Radioactive sources deliver therapeutic dose to
  tumors,
• preserving the surrounding healthy tissues

• Interstitial brachytherapy
• ( prostate)
• Endocavitary brachytherapy
• (lungs,vagina,uterus)
• Superficial brachytherapy
• (skin)

Brachytherapy

• Three devices

• precision in calculation of dose distribution
• reproduction of the real geometry and tissues (CT
  )
• calculation speed
• simple to use ( for hospitals !)

Software characteristics for brachytherapy

• Calculation of dose delivered to tissues

Commercial software available
Such a software does not exist for superficial
brachytherapy!
Advantages High
calculation speed
(as for example Prowes, Variseed V7) used in
clinical practice

• Analytical calculation methods
• All the tissues are approximated to water

• Disadvantages
• Approximated dose calculation
• density insensitivity
• The source is approximated to a point

Problem How to achieve accuracy and quickness?
Solution from HEP World Geant4 GRID WEB

• Speed is a fundamental requirement for software
  used in the clinical practice
• The medical physicist sometimes has got to take
  decisions about the position
• of the sources in few seconds
• MC simulation were never been used in the
  clinical practice for the long calculations

• Geant4 is an Object Oriented Toolkit for the
  simulation of the passage of particles through
  matter
• .Its application areas include high energy and
  nuclear physics experiments, astrophysics,
  medical physics, radiation background studies,
  radioprotection and space science.
• Geant4 exploits advanced Software Engineering
  techniques and Object Oriented technology to
  achieve the transparency of the physics
  implementation and hence provide the possibility
  of validating the physics results.
• Geant4 has been developed and maintained by a
  world-wide collaboration of more than 100
  scientists.
• The source code and libraries are freely
  distributed from the Geant4 web site
  www.cern.ch/geant4.

GRID is a project funded by European Union. The
objective is to build the next generation
computing infrastructure providing distributed
computering resources across the world
Project development of a software for dose
calculation which is accurate in the dose
calculation and fast by a clinical use point of
view
Development of the project

• 3D dose distribution calculation
• Isodose curves

• Test from a microscopic point of view

Tests

• Tests on Geant4 e- and gamma electromagnetic
  processes
• CSDA range for e- and Gamma attenuation
  coefficient in different absorber materials
• Comparison of different Geant4 physics models
  (Standard/LowEnergy/Penelope)
• Comparison with protocol data ( ICRU 37 and ICRU
  49)

Sofware planning and development

• MonteCarlo method
• Accurate physical processes simulation
• Test to guarantee the quality of the software

Precision

• Functionalities (User Requirements)
• Design
• Software Process (USDP)
• A rigorous software process permits
• the development of reliable software
• necessary feature for tools addressed
• to medical physics

• Macroscopic Test
• Test about the dose distribution of
  brachytherapic
• sources ( I-125, Ir 131) along the perpendicular
  to the
• major axes on the source .

• Accurate description of the geometry
• Possibility to interface the software to CT

Real geometry reproduction
Simulation Geant4

• Geant4 results have been compared with
• experimental measurements and protocol reference
  data (TG43 and
• Italian Association of Medical Physics (AIFB)
  protocol)

Analysis AIDA/Anaphe

• Graphic visualisation user interface
• Dose distribution analysis ( i.e. isodose curves)

• The experimental dosimetric measurements of the
  seed Microselectron HDR (Ir-131)
• have been performed with ionisation chambers at
  the Italian National Institute
• of Cancer (IST), Genova (Italy)
• The experimental measurements of the seed Bebig
  Isoseed I-125 have been
• performed with films at the Medical Physics
  Institute of Savona (Italy)

Simple to use , Use in hospitals
G. Ghiso and S.Guatelli At Medical Physics
Institute in Savona(Italy)
Calculation speed DIANE, GRID

• Parallel system
• Calculation shared resource access

Calculation speed

• Estensivity to new functionalities
• Public access

• Dose distribution calculation
• Isodose curves

Other user requirements
Brachytherapy application
For all the brachytherapic devices
Generalisation of the software
Use of abstract classes Radioactive source
definition thanks to the design pattern Abstract
Factory

• Generalization
• Specific aspects of the source
• Interface to CT
• Dosimetry

Functionalities

• Each treatment planning software is specific to
  one brachytherapic technique.
• Treatment planning software is expensive
• ( hundreds k Euro)
• The software we developed is transparent to the
  particular brachytherapic source this is
  possible because Geant4 simulates the involved
  physics without any approximation.

Parametrization of the volumes in the geometry
Parametrization function volume -gt material

• 3D dose distribution
• Isodose curves
• Choice of the materials of the phantom
• Graphical visualization
• Possibility to interface the system to CT
• source composition
• geometry, materials, spectrum

Simulation result energy deposit Analysis dose
distribution and isodose curves
Some Results
Dose distribution of a MicroSelectron- HDR source
(Ir-131)
On a average PIII machine, As an average
hospital may have
Performance
Leipzig applicator
Endocavitary brachytherapy
1M events 61 minutes
The plots describe the dose distribution in
plans parallel to the one containing the source
(y 0. mm)
The simulations are two slow The time required to
obtain results with high statistics do not
permit the use of MC in clinical practice

• The radioactive source is
• positioned in the center of a phantom
• filled with water.
• The results can be generalised to
• more seed and in a human anatomy

Interstitial brachytherapy
1M events 67 minutes
Problem The simulations are very long (compared
to clinical use scale of time) in order to obtain
results with high statistics.
Superficial brachytherapy
1M events 65 minutes
On up to 50 workers, LSF at CERN, PIII machine,
500/1000 MHz It is not realistic to expect
such CPU resources in the average hospital
Performance in parallel mode
Parallelisation and access to the GRID
Running on the GRID
Endocavitary brachytherapy
DIANE RD project Application oriented gateway
to GRID
1M events 4 minutes, 34 sec

• Via DIANE
• A hospital is not required to own and maintain
  extensive
• Computing resources to exploit the scientific
  advantages
• of MonteCarlo simulation of radiotherapy
• Any hospital even small ones- or in less wealthy
  countries,
• that can not afford expensive commercial software
  systems
• may have access to advanced software technologies
  and
• tools for radiotherapy
• Work in progress submission to the GRID and
  retrieval of
• results from a web portal(to facilitate the
  usage by end-users)

Migration to distributed environment

• DIANE permits the parallelisation on the
• application and the access to GRID
• The application developer is shielded
• from complexity of underlying technology

Interstitial brachytherapy
1M events 4 minutes, 36 sec

• The application developer is shielded from
  complexity
• and underlying technology
• Not affecting the original code application
• Good separation of the subsystem
• the application does not need to know that
  it runs in
• distributed environment

• Parallel cluster processing
• Make fine tuning and customisation easy
• Transparently using the GRID
• Application independent

Superficial brachytherapy
1M events 4 minutes, 25 sec
S.Agostinelli1, F.Foppiano1, S.Garelli1, G.Ghiso2
, S.Guatelli 3, J.Moscicki4, M.G.Pia3,M.Tropeano5
1.Cancer Institute (IST), Genova,Italy 2.Servizio
Sanitario Savona,Italy 3.INFN Genova,Italy,
4.CERN, Geneve,Switzerland, 5.University of
Genova,Italy