F. Foppiano, M.G. Pia, M. Piergentili Medical Linac IEEE NSS, October 2004, Rome, Italy...
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F. Foppiano, M.G. Pia, M. Piergentili Medical Linac IEEE NSS, October 2004, Rome, Italy [email protected]
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Transcript of F. Foppiano, M.G. Pia, M. Piergentili Medical Linac IEEE NSS, October 2004, Rome, Italy...
F. Foppiano, M.G. Pia, M. Piergentili
Medical Linac
IEEE NSS, October 2004, Rome, Italy
Intensity modulated radiation therapy
step and shoot
• Dose distribution more homogeneous within the PTV
• Much sharper fall-off of dose at PTV boundary
• Inhomogeneous dose distribution to treat concave surface
Progress in 3D medical imaging
Normal tissues exposed to high doses
can be reduced
Beam aperture is shaped to the irregular form of the target
Photon fluencies are modulated
Head and neckbreast
prostate
M.Piergentili
Problem Statement and General plan
Geant4
AIDA/Anaphe
OO tecnology
Specific software process
functionalities design Advanced software
Microscopic validation of Geant4 processes
Dosimetric validation of the sistem
Experimental measurements
Validation of the
dosimetric system
planning and developing
the dosimetric
system
simulation analysis+
DIANE
Statistical toolkit
Commercial systems
Analytic algoritmsAnalytic algoritmsEs.: Eclipse, Plato
speedy, but contain approximations
Determine the dose distributions given in a phantom by the head of a linear accelerator
M.Piergentili
Dosimetric system
The actual analysis produces some histograms from which the user can calculate the Percent Depth Dose (PDD), the lateral profiles at the following depths in the phantom: 15 mm, 50 mm, 100 mm and 200 mm, and the isodoses curves in a plane
Gaussian distribution for energy and momentum of primary particles
Each pair of jaws can be rotated through an axis that is perpendicular to the beam axis
The user can choose the position of every single leaf
M.Piergentili
Dosimetric system Flattening filter
MLC
Primary collimators and target
M.Piergentili
Design
FlexibilityExtensibilityDistributed responsibility
DecoratorDecorator
M.Piergentili
Software tecnologies
Mapped onto ISO 15504
Dinamic and static dimension
Based on use cases
Rational Unified Process
Specific software process for this dosimetric system
Software process artifacts
M.Piergentili
Experimental measurements with ion chamber
IAEA 398
Percent Depth Dose
Squared fields 5x5 cm, 10x10 cm, 40x40 cm
PTW 31002 Flexible.
PTW MP3
M.Piergentili
Comparison with experimental data
range D p-value
-84 -60 mm 0.385 0.23
-59 -48 mm 0.27 0.90
-47 47 mm 0.43 0.19
48 59 mm 0.30 0.82
60 84 mm 0.40 0.10
range D p-value
-56 -35 mm 0.26 0.89
-34 -22 mm 0.43 0.42
-21 21 mm 0.38 0.08
22 32 mm 0.26 0.98
33 36 mm 0.57 0.13
Kolmogorov-Smirnov testKolmogorov-Smirnov test
1010 events
100 CPU dayson Pentium IV 3 GHz
M.Piergentili
Comparison with experimental data
D = 0.005; p-value = 1
range D p-value
0 14 mm 0.548 0.09
15 300 mm
0.144 0.123
Kolmogorov-Smirnov test
Voxels 5mmVoxels 1mm
M.Piergentili
Experimental measurements with radiographics films
Kodak X-Omat V filmsScanner VXR16 Dosimetry ProSoftware Rit 113
Grey tone Optical density Dose
Spatial resolution = 89 m
Field used to treat prostate cancer
M.Piergentili
Comparison with experimental data
filmDose distribution
in a plane (dosimetric
system)
Isodose lines (RIT113)
Isodose lines (dosimetric system)
M.Piergentili
Conclusions
• Low-cost dosimetric system
• Package Low Energy • Validation of physical processes
in Geant4• Comparison with experimental
measurements
Future improvements
• Phase space• Dynamic tecnique
Thanks to Barbara Mascialino for the statistical analysis
This is an Advanced Example of
precision
Submission of a paper to IEEE Transaction on Nuclear Science
M.Piergentili
