Ian C. Smith 1 A portal-based system for quality assurance of radiotherapy treatment plans using Grid-enabled High Performance Computing clusters CR Baker 2, V Panettieri 3, C Addison 1, AE Nahum 3 1 Computing Services Dept, University of Liverpool; 2 Directorate of Medical Imaging and Radiotherapy, University of Liverpool; 3 Physics Department, Clatterbridge Centre for Oncology

Rationale  MC codes can provide accurate absorbed dose calculations but are computationally demanding  Desktop machines not powerful enough, need parallel hardware e.g. High Performance Computing (HPC) clusters  Aim to exploit local and centrally funded HPC systems in a user- friendly manner  Two MC codes have been investigated to date:  MCNPX (beta v2.7a)  Parallel (MPI-based) code  General purpose transport code, tracks nearly all particles at nearly all energies (  PENELOPE  serial implementation  general purpose MC code implemented as a set of FORTRAN routines  coupled electron-photon transport from 50 eV to 1 GeV in arbitrary materials and complex geometries [1]. [1] Salvat F, Fernández-Varea JM, Sempau J. PENELOPE, a code system for Monte Carlo simulation of electron and photon transport. France: OECD Nuclear Energy Agency, Issy-les-Moulineaux; ISBN Available in pdf format at:

Grid Computing Server / UL-GRID Portal

Grid Computing Server / UL-GRID software stack

MCNPX Job Submission

PENELOPE Job Submission

PENELOPE (serial code) workflows  Rereasdasdas create random seeds for N input files using clonEasy[1] combine N individual phase-space files compute individual phase-space file create random seeds for N input files using clonEasy[1] stage-in phase-space file (only if necessary) compute partial treatment simulation results combine partial treatment simulation results using clonEasy[1] repeat for other patients phase-space file calculation patient treatment simulation Portal HPC cluster [1] Badal A and Sempau J 2006 A package of Linux scripts for the parallelization of Monte Carlo simulations Comput.Phys. Commun –50

External beam photon treatment modelled using PENELOPE Three 6 MV beams Resolution: 256 x 256 ( x 51 CT slices) Final average dose uncertainty 2% (2σ)

MCNPX: Proton beam modelling 29 May 2009 Clatterbridge proton facility Baker, Quine, Brunt and Kacperek (2009) Applied Radiation and Isotopes 67; 3:402 Protons transported through the beam-line (scattering system, range-shifters, modulators and collimators). ~2m Incident spectrum fitted to measured Bragg peak Generic phase-space file generated at the position of the modulator and subsequently transported through patient-specific range-shifter and modulator

29 May cm diameter beam, full energy (~60 MeV at patient, ~3.2 cm range in water) 500 million histories 0.5x0.5x5 mm voxels 50keV proton cut-off <1% statistical uncertainty in absorbed dose in high dose region (1  ) Bragg peak Half-modulation Proton absorbed dose in water

Timing Results  PENELOPE (Serial)  Phase-space file calculation  4 days per beam on 7 cores  700 x 10 6 particles per file  Patient calculation  1 simulation required 4 days on 1 core  1 simulation on 32 cores should only require 3 hours  MCNPX (Parallel under MPI)  500 million histories over 32 cores, < 4 hours, without variance reduction applied.

Future Directions  Expand portal interface to include submission of job workflows  Provide support for BEAM [1] and DOSxyz [3] (based on the EGSnrc MC code [2] )  Possible use of Windows Condor Pool to create PSFs for PENELOPE References: [1] 23D. W. Rogers, B. Faddegon, G. X. Ding, C. M. Ma, J. Wei, and T. Mackie, “BEAM: A Monte Carlo code to simulate radiotherapy treatment units,” Med. Phys. 22, 503–524 _1995_. [2] Kawrakow and D. W. O. Rogers. The EGSnrc Code System: Monte Carlo simulation of electron and photon transport. Technical Report PIRS-701 (4th printing), National Research Council of Canada, Ottawa, Canada, [3] Walters B, Kawrakow I and Rogers D W O 2007 DOSXYZnrc Users Manual Report PIRS 794 (Ottawa: National Research Council of Canada)