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Development of Accurate Radiotherapy Treatment Planning System (ARTS) Presented by Song Gang FDS team Institute of Plasma Physics Chinese Academy of Sciences gang@ipp.ac.cn Http://www.fds.org.cn ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007

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Background

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Objectives and Issues of Radiotherapy Objectives Kill tumor cells to the great extent Protect the normal tissues and important organs at the most Main Issues Normal tissues damaged in radiotherapy Great difference (including material, structure, sensibility to radiation, etc. ) individually Uncertainty of radiation biological effect External exposure treatment ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007

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General View of Radiotherapy System Much fundamental research was performed on the above key study points ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007

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Present Status 10 million newfound cancerous persons per year in the world 70% cancerous persons need radiotherapy Great application potential, but therapeutic effect is still uncertain in some extent and should be improved: Now the radiotherapy technique can not realize accurate radiotherapy essentially Error of dose calculation: >3%; in extreme condition: up to 30%; Dose verification: by standard homogeneous phantom or water phantom, not actual human or emulated human phantom; Position: by laser lines and marks on body, large error caused by change of contour; ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007

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Progress

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Main Research Issues (1) 1.Recognition technique of human physical information and model building method based on CT images; 2.Digital human model set up, calculation model and visualization method of dose distribution. 3.Simulation of particle transport (neutron, photon, and electron) in human body and development of calculation algorithms for dose distribution in human body; ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007

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4.Algorithm for multi-objective optimization of inverse planning; 5.Fast and precise video-based automatic positioning method; 6.Design of emulated human phantom and development of verification method; 7.Accurate/Advanced Radiation Therapy System (ARTS), proposed and developed based on modern computer technology and digital simulation method for nuclear physics. ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007 Main Research Issues (2)

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Automatic Model Set up Method From 3-D medical images (adding material and density information) to calculation model, including both geometrical and physical information ( CT/MRI images -> Digital human model -> Calculation model ) MCAM ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007 MORP Medical Images MCNP Input File Visualization of Dose Calculation Model MCAM: Monte Carlo Automatic Modeling SystemMORP: Modeling of Radiotherapy Program

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Accurate & Fast Dose Calculation Method Regular Beam Model (RBM) + Modified Batho homogeneity correction method: Error: below 3 %, speed: within 1 minute, for regular field Modified Pencil Beam Model (fsPB) Error: below 3 %, speed: within 1 minute, for irregular field Accurate and precise coupled dose Calculation Method Analytic method: used in homogeneous region; Monte Carlo method: used in inhomogeneous region; high precision & speed The above dose calculation methods : all developed or modified by ARTS team Monte Carlo methods: EGS4, MCNP, etc. Discrete coordinate (SN) (1D/2D/3D) Nuclear Database ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007 Research progress: Poster 264 & 267

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Multi-dimension & Multi-field Visualization 3D dose distribution 2D dose distribution ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007 CDVH Outside contour of human body are gotten by outside contour extraction based on CT numbers Improved edge flag filling algorithm be used to fill objects Real-time visualization for outside contour, object, field and overlapping of which are implemented by surface rendering Visualization of key information make TPS (ARTS) more valuable

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Multi-objective Optimization of Inverse Planning Two multi-objective optimization algorithms used in ARTS: ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007 SAGA could obtain satisfactory solutions in 15 minutes NSGA-II could obtain satisfactory solutions in 5 minutes Use above methods to optimize dose distribution on a slice of CT: Introduced NSGA-II to ARTS with some improvement. NSGA- -II is a fast and elitist multi-objective optimization algorithm. Research progress: Poster 263 Hybrid multi-objective optimization algorithm (SAGA) Combined Simulated annealing algorithm and genetic algorithm, whose displacement is based on the evolutionary calculation and improve the ability of global optimization. Non-dominated Sorting Genetic Algorithm-II (NSGA-II)

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Video-Based Fast and Accurate Positioning Method Video positioning method with marks on body surface Breathe gate system Video positioning method without marks on body surface Based on the stereo vision and photogrammetry technique to calibrate the video camera with special demarcated lock Based on dynamic template matching technique to reduce the influence caused by the contour change of patient Positioning error is less than 1mm Positioning process takes less than 30 seconds Rebuild 3-D images with virtual net technique Compute the positioning error with inverse reconstruction Contour matching technique Eliminate the positioning error caused by the patients breath and organs movement Easy realization Three positioning methods developed and used in ARTS:

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Dose Verification Traditional dose verification: water-to-man dose verification simple homogenous phantom / water phantom Complex, time-consuming To be developed: man-to-man dose verification Use the external dose information of the practical case to inverse the internal dose distribution. Simple, less-work, and real time Progress : Rapid and accurate inversion calculation of three-dimensional electron dose based on hybrid pencil beam model Applied the method of nonlinear inversion for parameter based on hybrid pencil beam model (HPBM), and used external dose information of the practical case to inverse the internal dose distribution, a "man- to-man " dose verification method. Research progress: Poster 265

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Results Homogeneous case (Fig.1): inversion time: about 3s (CPU: 2.0GHz, Win XP), and mean accuracy: 99.86% Inhomogeneous case (Fig. 2): inversion time: about 5s (CPU: 2.0GHz, Win XP), and mean accuracy: 99.5% Conclusion: Formed "man-to-man" dose verification Method; Developed the inversion algorithm of electron dose field based on HPBM, in both homogenous and inhomogeneous rapidly and accurately. Figure 2. Off-axis to on-axis dose in water-lung- water model (1cm-2cm-100cm), data from our Monte Carlo (EGSnrc) simulation, 10x10cm 2 applicator,10x10cm 2 field, 10MeV electron energy. Figure 1. Off-axis to on-axis dose in water. 10 cm x10 cm applicator, 10x10cm2 field, 10MeV electron energy, SSD=95cm in water, and data from our experiment with PDD.

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The emulated phantom can realize the following similarities: External shape / chemical component / internal structure / energy deposit Emulated Phantom Development and Dose Distribution Verification ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007 Dose verification experiment was carried out by the phantom to verify the RBM+ Modified Batho dose calculation method. Varian 23EX accelerator, SSD 100cm, 10cm 10cm field, 6MV photon: Meaning error between calculation and measurement: below 3%

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Interface of ARTS ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007

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Summary

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1. ARTS team of ASIPP is developing an advanced treatment planning system to solve current problems in radiotherapy; 2. Visualization, dose calculation, dose verification, inverse calculation, position, optimization, and biological effect are studied within the frame of ARTS; 3.Based on the above study, a prototype TPS system (ARTS) has been developed; 4.Some problems, especially on biological effect and fast/accurate dose calculation method, to be solved. ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007

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Study Progress and Introduction Materials of MCAM & ARTS: Poster 263, 264, 265 and 267 now! B1F Lobby Gallery at Glass Building

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Thank you

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Staff: ~600 Students: ~ 300 Academy of Sciences, Institute of Plasma Physics ASIPP ( http://www.ipp.ac.cn ) ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007 Preparatory

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FDS team FDS team Fusion Driven (Subcritical) System Fusion Design Study Fusion Digital Simulation Staff: ~20 Students: ~40 ~30 Ph.D ~20 M.D ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007 Photo Album of FDS team Preparatory

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Seven research groups: 1. Neutron (photon, electron) physics 2.Radiation Safety (Accurate radiotherapy, Radiation Protection) 3.Thermohydraulics & structure 4.Nuclear material & cladding technology 5.Radiochemistry (Nuclear waste disposal) 6.System engineering (Optimization, Risk, Economy 7.Computer technique Research Field and Structure of FDS Team Four laboratories: 1.Radiation safety & environment protection 2.Nuclear material & cladding technology 3.Nuclear waste disposal 4.Digital simulation & Visualization Advantages of FDS team: 1. Multi-disciplinary research physics / heat engineering / material / chemistry / safety / economics / medicine / computer technique / mathematics / electronics 2. Fundamental research of CAS, long-time fund support 3. Broad international cooperation ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007 Preparatory

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Multi-disciplinary Team Radiation physics Reactor Technology Division, ASIPP one of the strongest groups in the relevant area in the world H. Iida ITER-NAKA Computer technology Digital simulation & visualization Team of 100 Talents Programme of The Chinese Academy of Sciences Radiation biology Ion beam engineering major laboratory of the Chinese Academy of Sciences Team supported by National Science Fund for Distinguished Young Scholars ________________________________________________________________ G.SONG, International Nuclear Physics Conference 2007, Tokyo, Japan, June 3-8, 2007 Preparatory

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Thank you