Genova 8 Marzo 2004 Radiotherapy treatment planning with

Genova, 8 Marzo 2004 Radiotherapy treatment planning with Monte Carlo on a distributed system Stéphane Chauvie, IRCC & Mauriziano Hospital & INFN & S Croce e Carle Hospital Turin, Italy

Contents Radiotherapy Treatment Planning Analitical algorithms for dose calculation Monte Carlo methods Cluster set-up Monte Carlo parallelization Data analisys and experimental comparison: open field and IM field measurements Head and neck tumor with IMRT Grant 2002 -03/645

Radiotherapy Oncology spare the surrounding healthy tissues. deliver high dose to the target volume PTV Pharot CTV id allow local control of tumor S. c. PRVSpinal cord avoid sideeffects

3 D-CRT vs IMRT Critical points: - high dose gradients - strongly unhomogeneous areas 3 DCRT & IMRT used in complex anatomical regions IM field How much is accurate the dose calculation ?

Dose calculation algorithms • Pencil beam • Monte Carlo • Convolution/Superposition Expensive Accurate but very slow Quick but inaccurate Cheap (free) Dose determination accuracy Total with dose calculation Meas in ref pomint, neam stability &flatness, CT data, setup 4, 1% 4, 2%(1%) to 6, 5% (5%) Ahnesjo 1999

Cluster Beowulf parallelisation + PC & Ethernet Th: High performance networks of PCs are now realistic alternative since offer parallel processing of MC at a lower cost showing competitive performances. = Beowulf

Cluster set-up Hardware installation Monte Carlo Software configuration simulation Benchmarking Monte Carlo parallelisation RUN

Installation, configuration & benchmarking Bios OS Disk conf Partition RAID Memory CPU Compilators Linking models Parallelization: LAM-MPI to H-LAN Master S W I T C H Node 02 Node 03 Node 04 Node 05 Node 06 Node 07 Node 08 Security: SSH

Installation, configuration & benchmarking to H-LAN Master S Node 02 W Node 03 I Node 04 T Node 05 C Node 06 H Node 07 Sup = Tser/Tpar = 3. 99 Node 08 Efficiency = Sup/ Nprocessors = 0. 997

Simulation: geometry V = 6 MV e- Varian 600 C/D Millenium 120 -leaf MLC

simulation: physics Processes Multiple scattering Bremsstrahlung Particle e- Ionisation e+ Annihilation Photoelectric effect Compton scattering Rayleigh effect conversion e+e- pair production Geant 4 has only production thresholds, no tracking cuts l all particles are tracked down to zero range l energy, TOF. . . cuts can be defined by the user NO TUNING, NO CUT

Patient model Soft tissue: Bone: - CT- el linearity - cortical bone - bone marrow diluition Lung: - CT- linearity DICOM interface - CT-tissue relationship ICRU

Monte Carlo Parallelization Take care of PRNG IM simple field in homogeneous phantom Phase Space Data Water measurements IM patient field in homogeneous phantom Anthropomorphic phantom measurements Simulation inside patient IMRT treatment

Phase Space Data PSD (x, y, z) (px, py, pz) E

Water measurements 10 X 10 PDD % PDD and dose profile in water 20 X 20 Scanner IC 15 ionization chamber SSD=SAD

Anthropomorphic phantom measurements Measure 100, 0 2, 4 Monte Carlo 100, 0 2, 2 Diff % 0, 0 178, 4 3, 0 120, 1 2, 7 98, 8 3, 4 175, 4 2, 3 -1, 7 118, 0 2, 2 -1, 7 97, 0 2, 3 -1, 8 Broad Diff Pencil Diff beam % 103, 1 102, 9 Super/ Diff conv % 101, 9 166, 0 -6, 9 122, 3 1, 8 100, 0 1, 2 176, 3 -1, 2 121, 8 1, 4 98, 3 -0, 5 Microchamber A 14 SL 173, 2 -2, 9 124, 7 3, 8 107, 0 8, 3 SSD=SAD

Patient simulation X=10 Y=10 SSD=SAD Gantry 0° TAC

IMRT treatment simulation 10 X 10 E=0. 9925 isocentric technique 7 field! Every field segments no. 165, 4 15, 3 events no. (15, 5 0, 5)107 hits no. (4, 02 0, 39) 105 time (hours) 0, 51 0, 03 IMRT plan evaluation in 3, 5 hours with 280000 hits and 3 nodes

Current ”Geant 4” activities in Cuneo. . . 10 Me. V Cyclotron CT-PET