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Radiotherapy, hadrontherapy and treatment planning systems.
Faiza Bourhaleb INFN-Torino
University Med 1er-Morocco Radiotherapy Optimization techniques Hadrontherapy Treatment planning ANCOD++ Perspectives
NURT-Havana 25 October 2001
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Radiotherapy, the history:
RT as an inter-disciplinary technique.
Conventional RT !!??No: Too many error sources due to
a large rectangularly shaped fields bad definition of tager volume to irradiate.
Since 1973, conformational RT.
The Intensity Modulated RT birth => MLC
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Optimization and treatment planning
Patient steps before treatment CT and 3D definition of the global volume for treatment.Doctors prescription. Planning of the treatment?
Optimizing a TP Forward planning Monte Carlo simulation Inverse planning
ANCOD++ !??
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Why we should think to some thing else!!!
The solution is it an inverse planning, and what about optimization of beam intensities.
The beams intensities are the unique free parameter.
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Inverse planning:
Asking help from mathematics and numerical calculation
Big variety of algorithm already exciting:
Conjugate Gradient minimization.
Quasi Newton minimization.
Simulated annealing minimization.
All to resolve a simple linear system:
voxel),()( beamdwvoxelDbeam
beamrequired
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Physical properties of protons and carbon ions
Particularities of hadrontherapy.
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Biological properties
Alpha particles
Carbon ions
Double strand break
Lethal event
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Relative biological efficiency:
For the same biological effect show that we need much less dose delivering. Possibility of cell repair decrease in a considerable way.
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Treatment planning in hadrontherapy.
Patient information: AnatomyCT images for treatment
Doctors prescriptions considering devices limitations for the treatment.
Optimization technique: Mathematic algorithm2D or 3D optimization!
Display of final 3D dose distribution and notion of DVH.
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Voxel scan technique adopted:
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ANCOD++ description
VOXELCTTarget
AcceleratorFieldEnergyOptimize
Dose
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ANCOD++, results
100
40
Dose
X
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DVH inside target
DVH outside target
NB:comparison with IMRT ?
Vol
ume%
Dose%
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Comparison: IMRT Protons
Abdomen
Brain
Between eyes
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ANCOD++ GEANT 3
ANCOD++ and GEANT3 simulation
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The future !!??
Hadrontherapy has a big chance to be the therapy of the future since it has really minimum possible side effects, sparing as no other technique can do the organs at risk. It adopts the newest techniques of treatment planning, optimizing time and in that way money also. It is now a technique a bit expensive comparing with therapies with photon or electrons but like all the new technologies at the beginning the precision costs a lot but then the expenses decrease quickly with time.
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Thanks!!
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Filter degrader
Cancer
Bolus
Final collimator
scatterer
Ridge filter
Ridge filter
First collimator
Bolus
Final collimator
Body
Revolution and era of Conformational RT:
Blocks
Filters
Wedges
Compensators
Collimators…..
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The IMRT birth => MLC.
Gantry with an DMLC
The Multivane Intensity modulating Collimator (MIMIC).
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Iterative method used in our software.
Dose required in a specific voxel is changed in each iteration for the new one with correction.
We start considering the supervising weight the one of the beam steered in the actual voxel to have the Bragg peak there and so the maximun of energy deposition.
However it is necessary to iterate many times to join the compromise between different beams to respond the best to our requirements and prescriptions.