HAL Id: cea-02557601
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Submitted on 30 Apr 2020
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Validation of Dose Calculations with PENFAST (a Fast
Monte Carlo Code for TPS in Radiotherapy) Using a
Beam Energy Spectrum Reconstructed by a Least
Squares Method
Bouchra Habib, François Tola, Jean-Marc Bordy, Bénédicte Poumarède
To cite this version:
Bouchra Habib, François Tola, Jean-Marc Bordy, Bénédicte Poumarède. Validation of Dose
Calcu-lations with PENFAST (a Fast Monte Carlo Code for TPS in Radiotherapy) Using a Beam Energy
Spectrum Reconstructed by a Least Squares Method. American Association of Physicists in Medicine
Annual Meeting (AAPM 2008), Jul 2008, Houston, United States. publié dans Medical Physics, 35
(6 Part 15 : General poster discussion), page 2808- Poster SU-GG-T-361, 2008, �10.1118/1.2962113�.
�cea-02557601�
Validation of dose calculations with PENFAST
(a fast MC code for TPS in radiotherapy) using a beam
energy spectrum reconstructed by a least squares method
B HABIB, B POUMAREDE, JM BORDY, F TOLA, J BARTHE
CEA, LIST, Department of Technology for Sensors and Signal Processing, F-91191 Gif-sur-Yvette, France. bouchra.habib@cea.fr
AAPM annual meeting – Houston, July 27 - 31, 2008
Conventional TPSare fastbut generally not enough accurateespecially in presence of heterogeneities where the electron transport effects cannot be accurately handled with conventional deterministic dose algorithms.
Implementation of Monte-Carlo (MC) methods allows better accuracy.
Recently, a fast MC dose calculation code, named PENFAST (a private code) has been developed by Salvat et al (2008). PENFAST is an optimized version of the conventional MC PENELOPE code, adapted to CT voxelized geometries.
In this work, PENFAST calculations of dose distributions in homogeneous and heterogeneous phantoms were compared with PENELOPE (version 2006) calculations as well as experimental data.
Context and objectives
Materials and Methods
Detailed modeling of the LINAC Saturne 43 (located at the French National Metrological Laboratory for ionizing radiations).
Primary electrons characterization using a least squares method with no negativity constraints (NLS) coupled with PENELOPE dose simulations in water.
Results and Discussion
Homogeneous phantom comparisons
Conclusions
Saturne 43, electrons 18 MeV : Depth dose curves
Phase Space File calculation
PENFAST simulation of dose distributions
in voxelized heterogeneous phantoms
0 0.2 0.4 0.6 0.8 1 1.2 0 20 40 60 80 100 120 140 Depth (mm) R e la ti v e d o s e Measurements PENELOPE 13.5 MeV PENELOPE 14.5 MeV PENELOPE 15.5 MeV PENELOPE 16.5 MeV PENELOPE 17.5 MeV PENELOPE 18.5 MeV PENELOPE 19.5 MeV PENELOPE 20.5 MeV PENELOPE 21.5 MeV PENELOPE 22.5 MeV PENELOPE 23.5 MeV bone lung 5cm (ph) 2cm 8cm Water 30×30cm² 40×40cm² 40cm 3cm (el) lung Water 30×30cm² 40×40cm² 40cm 10cm 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 16 16.5 17 17.5 18 18.5 19 19.5 20 E (MeV) R ela ti ve p ro ba bilit y P (E ) dE 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0 2 4 6 8 10 12 14 Depth (cm) R e la ti v e d o s e 0 0.2 0.4 0.6 0.8 1 1.2 Γ (1 % -1 m m ) Measurements PENELOPE PENFAST Γ(1%-1mm) PENELOPE Γ(1%-1mm) PENFAST 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0 2 4 6 8 10 12 14 Depth (g/cm²) R e la ti v e d o s e NACP-02 PTW-34001 Fricke PENFAST PENELOPE
water lung water
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 5 10 15 20 Depth (g/cm2) R e la ti v e d o s e NE-2571 PTW-31002 Fricke PENFAST PENELOPE
water bone lung water
Heterogeneous phantom comparisons
Saturne 43, photons 12 MV 0.0 0.2 0.4 0.6 0.8 1.0 1.2 -12 -8 -4 0 4 8 12 Distance (cm) R e la ti v e d o s e 0 0.2 0.4 0.6 0.8 1 1.2 Γ (1 % -1 m m ) Measurements PENELOPE PENFAST Γ(1%-1mm) PENELOPE Γ(1%-1mm) PENFAST
The homogeneous phantom study allows us to validate the PSF calculations and illustrates that the NLS method provides an accurate description of the radiation source energy spectrum.
The overall excellent agreement between PENFAST and PENELOPE codes, as well as measurements, validates the accuracy of the fast MC code PENFAST for photon and electron dose calculations in clinically relevant heterogeneous phantoms and under metrological conditions.
Complementary tests will be performed before using PENFAST in a clinical environment : small field conditions, complex compositions.
PENFAST calculations are within ± 2% relative difference with measurements in the heterogeneous phantoms.
PENELOPE and PENFAST dose distributions in water are within ± (1%, 1 mm) relative difference with measurements.
Saturne 43, electrons 18 MeV Example of an energy spectrum reconstructed by a NLS method Saturne 43, electrons 18 MeV : Dose profiles
