Presentation on theme: "Current Topics in Monte Carlo Treatment Planning McGill University, Medical Physics Unit May 3-5, 2004, Montreal, Quebec, Canada The Monte Carlo SRNA-VOX."— Presentation transcript:
Current Topics in Monte Carlo Treatment Planning McGill University, Medical Physics Unit May 3-5, 2004, Montreal, Quebec, Canada The Monte Carlo SRNA-VOX code for 3D proton dose distribution in voxelized geometry using CT data Radovan D. Ilić, Vesna Spasić-Jokić, Petar Beličev and Miloš Dragović Institute of nuclear sciences Vinča TESLA Accelerator Installation www.tesla-sc.org www.vin.bg.ac.yu/~rasa/hopa.htm
GENERAL-PURPOSE MONTE CARLO PROGRAM SRNA FOR PROTON TRANSPORT SIMULATION Proton therapy; Accelerator driven system design; Radioisotopes production for medical applications; Simulation of proton scatterer and degrader shapes and composition Radiation protection of accelerator installations
SRNA 2-KG attributes Original author: Radovan D. Ilić, Ph.D, VINCA Institute of Nuclear Sciences General Purpose: Numerical experiments for proton transport, radiotherapy and dosimetry Secondary particles: protons transported as the protons from source Proton energy range: 100 keV to 250 MeV Material Database: 279 elements: Z = 1-99, compounds and mixtures: 181,limited by available ICRU63 cross sections data Material geometry: 3 D – zones distributed by I and II order surfaces or in 3D voxelized geometry Program Language: Fortran 77 for Linux or Windows
SRNA-VOX MONTE CARLO CODE Simulation model:. Multiple scattering theory of charged particles (Moliere angular distribution, Berger). Energy loss with fluctuation (ICRU49 functions of stopping power, Vavilov's distribution with Schulek's distribution correction per all electron orbits ). Inelastic nuclear interaction (ICRU 63, Young and Chadwik 1997). Compound nuclei decay (our simple and Russian MSDM models). CT numbers describing 3D patient’s geometry. Correlation between CT numbers and tissue parameters: mass-density and elemental weight Numerical experiments set-up:. Energy range from 100 keV to 250 MeV. Materials limited by available ICRU63 cross sections data. Circular and rectangular proton sources in 4Pi with applied spectra. DICOM picture and sampling region for irradiation. Probabilities and data preparation by SRNADAT code. 3D dose presentation on patient anatomy
Comparison of the SRNA package (R.D.Ilić) Comparison of proton depth dose distribution obtained from Monte Carlo numerical experiments by SRNA-2KG and GEANT-3 codes Comparison of proton depth dose distribution obtained from Monte Carlo numerical experiments by SRNA-2K3 and GEANT-4 codes SRNA-2KG, GEANT3, SRIM Simulation and MLFC measurements at 205 MeV proton Indiana Univ. Cycl. Facility, USA Intercomparison of the usage of computational codes in radiation dosimetry, Bologna, Italy, July 14-16 2003
Comparison of proton depth dose distribution obtained from Monte Carlo numerical experiments obtained from Monte Carlo numerical experiments by SRNA-2KG and GEANT-3 codes by SRNA-2KG and GEANT-3 codes
Multi layer Faraday Cup (MLFC) experiments WHY: To specify the proton beam from accelerator and verify the quality and reproducibility of the proton beam for the proton therapy. WHO: Indiana University Cyclotron Facility HOW: Monte Carlo simulation by SRIM, SRNA-2KG and GEANT3 data compared with actual measurement data RECOMMENDATION: A simple test for nuclear interaction model can be checked by MLFC. Every Monte Carlo code to be used in charged particle therapy should pass this test
SRNA-2KG, GEANT3, SRIM Simulation and MLFC measurements at 205 MeV proton Indiana Univ. Cycl. Facility, USA Mascia A.E., Schreuder N., Anferov V.August 2001
H. Paganetti B. Gottschalk interaction Test of Monte Carlo nuclear interaction models for polyethylene (CH 2 ) using a multi-layer Faraday cup The MLFC is an excellent and simple tool to test nuclear interaction models This is a clean benchmark (100% acceptance, charge (not dose) measurement) Works for high-Z and low-Z materials Every Monte Carlo code to be used in charged particle therapy should pass this test
A parallel beam of protons from a disk source (diameter 15 mm) impinges on a PMMA compensator (cylindrical symmetry) and on a spherical water phantom approximating an eye (figure 1). All elements are in vacuum. If discrete regions are used for dose calculations (depth-dose and isodose curves), use voxels with dimensions 0.5 x 0.5 x 0.5 mm3. The results should be normalized to one primary proton
INTERCOMPARISON OF THE USAGE OF COMPUTATIONAL CODES IN RADIATION DOSIMETRY Bologna, Italy, July 14-16 2003 Stefano Agosteo Dipartimento Ingegneria Nucleare,Politcnico Milano, Italy S: Fluka 2002 P3-F: srna-2kg
SRNA-VOX: Deposited proton energy in eye 50 MeV circular proton beam with 1.2 cm radius CT data: slice thickens 0.5 cm; pixel dimension 0.081 cm
ISTAR –proton dose planning software Trends in proton therapy planning: Development of the Monte Carlo proton transport numerical device capable of producing a therapy plan in less than 30 minutes and Development of clinically acceptable on-line procedures comprising all steps necessary for proper patient treatment. ISTAR software solved the first of these problems Why ISTAR ?
PROTON DATA PLANNING window Picture Planning Data - information about the boundaries of the space selected for simulation; Beam geometry with fields for selection of the beam shape (rectangular or cylindrical) and dimensions, Euler angles defining the direction of the beam axis with respect to the selected "Beam center", and polar and azimuthally angles of the proton emission within the local SRNA-VOX coordinate system; Simulation setup with fields for selection of proton energy (mean energy and standard deviation for Gaussian distribution, or custom defined spectrum), simulation cutoff energy, number of proton histories and the simulation time limit. The result of these actions is written in two files: (i) Hound.txt containing data about the defined region, proton source and Houndsfield's numbers for all voxels of the region; (ii) Srna.inp with the setup data for simulation.
Beam geometry and simulation setup TThe tumor location is defined using the CT image with sufficient precision -The irradiation plan begins with the selection of the tumor region within a rectangular box -The selected region is defined by the indices of the first and the last CT slice in the longitudinal (Z) direction, and by marking the area in the transversal (X-Y) plane
Final CT and geometry data selection, and making files for set-up the proton dose simulation ISTAR - Proton dose planning software
Proton dose distribution Table of Houndsfield’s numbers with average densities and tissue composition (Scheinder et al) SRNADAT ISTAR SRNA-VOX Srna.inp file and the Hound.dat file, converted from Hound.txt – start of simulation 1.6 GHz/512 MB PC, the simulation time for 65 MeV protons beam containing 10 6 particles, is around 10 minutes "Open REDOSE Image" menu item, the values of the absorbed proton dose are displayed over the CT slice image. Values can be normalized either to the maximum value in the slice, or to the maximal value in the entire irradiated region. Image viewing commands include a transparency (blending) intensity control. The code allows selection of different palettes, for displaying various isodose levels.
Dose distribution in equatorial eye plane, simulated by the SRNA-VOX code, using 50 MeV protons with 1.2 MeV energy spread. The isodoses are at the values of 20, 60, 80 and 100 % of dose maximum. 50 MeV with spread 1.2 MeV 20 % 60 % 80 % 100 %
Dose distribution in breast in central beam plane simulated by the SRNA- VOX code using 65 MeV protons with 1.5 MeV energy spread. The isodoses are at the values of 20, 60, 80 and 100 % of dose maximum. 20 % 60 % 80 % 100 %
ISTAR advantages - Software is based on the knowledge and experience acquired in working on the SRNA - It is capable to accept CT data for defining patient’s anatomy and tissue composition - A simple procedure for selecting the irradiation area and incident proton beam parameters allow fast and comfortable calculation of the dose distribution and visualization of it in each CT recorded slice of the patient’s body. - Execution time is short enough to be introduced in clinical practice. - The statistical error of the obtained results can be made almost arbitrary small by simple increase of the number of the proton histories to a few millions, without exceeding e.g. 30 min as acceptable computer run time.
CONCLUSION SRNA package advantages: Enlargement of the proton energy range, Increasing the efficiency of the implemented algorithms in order to Decrease the time necessary for proton transport simulation Motivation for ISTAR proton dose planning software development were good results of verification of SRNA package