A review of FLUKA applications for medical physics G. Battistoni, INFN Milano Contributions of: T.T. Böhlen, F. Cappucci, P. Colleoni, M. Chin, A. Ferrari, A. Mairani, S. Muraro, R. Nicolini, P. Ortega, K. Parodi, V. Patera, P. Sala, V. Vlachoudis (and others)

FLUKA Main authors: A. Fassò, A. Ferrari, J. Ranft, P.R. Sala Contributing authors: G. Battistoni, F. Cerutti, M. Chin, T. Empl, M.V. Garzelli, M. Lantz, A. Mairani, V. Patera, S. Roesler, G. Smirnov, F. Sommerer, V. Vlachoudis Developed and maintained under an INFN-CERN agreement Copyright 1989-2013 CERN and INFN >5000 users http://www.fluka.org

The FLUKA International Collaboration M. Brugger, M. Calviani, F. Cerutti, M. Chin, Alfredo Ferrari, P. Garcia Ortega, A. Lechner, C. Mancini-Terracciano, M. Magistris, A. Mereghetti, S. Roesler, G. Smirnov, C. Theis, Heinz Vincke, Helmut Vincke, V. Vlachoudis, J.Vollaire, CERN G. Kharashvili, Jefferson Lab, USA J. Ranft, Univ. of Siegen, Germany G. Battistoni, F. Broggi, M. Campanella, F. Cappucci, E. Gadioli, S. Muraro, R. Nicolini, P.R. Sala, INFN & Univ. Milano, Italy L. Sarchiapone, INFN Legnaro, Italy G. Brunetti, A. Margiotta, M. Sioli, INFN & Univ. Bologna, Italy V. Patera, INFN Frascati & Univ. Roma Sapienza, Italy M. Pelliccioni, INFN Frascati & CNAO, Pavia, Italy A. Mairani, CNAO Pavia, Italy M. Santana, SLAC, USA M.C. Morone, Univ. Roma II, Italy K. Parodi, I. Rinaldi, LMU Munich, Germany L. Lari, Univ. of Valencia, Spain A. Empl, L. Pinsky, B. Reddell, Univ. of Houston, USA M. Nozar, TRIUMF, Canada V. Boccone, Univ. of Geneva, Switzerland K.T. Lee, T. Wilson, N. Zapp, NASA-Houston, USA T. Boehlen, S. Rollet, AIT, Austria A. Fassò, R. Versaci, ELI-Beamlines, Prague, CR M. Lantz, Uppsala Univ., Sweden S. Trovati, PSI, Switzerland P. Colleoni, Ospedali Riuniti di Bergamo, Italy M.V. Garzelli, Nova Gorica Univ., Slovenia Anna Ferrari, S. Mueller HZDR Rossendorf, Germany

The Physics Content of FLUKA 60 different particles + Heavy Ions Nucleus-nucleus interactions from Coulomb barrier up to 10000 TeV/n Electron and μ interactions 1 keV – 10000 TeV Photon interactions 100 eV - 10000 TeV Hadron-hadron and hadron-nucleus interactions 0–10000 TeV Neutrino interactions Charged particle transport including all relevant processes Transport in magnetic fields Neutron multigroup transport and interactions 0 – 20 MeV Analog calculations, or with variance reduction

FLUKA Applications Cosmic ray physics Neutrino physics Accelerator design ( n_ToF, CNGS, LHC systems) Particle physics: calorimetry, tracking and detector simulation etc. ( ALICE, ICARUS, ...) ADS systems, waste transmutation, (”Energy amplifier”, FEAT, TARC,…) Shielding design Dosimetry and radioprotection Radiation damage Space radiation Hadron therapy Neutronics

Application for medicine: some examples Nuclear Medicine Dosimetry Radiotherapy Simulation of therapy devices Check of treaments Hadrontherapy Commissioning of facilities Treatment planning and forward checks Predictions for monitoring applications (imaging for hadrontherapy) Design of instruments, dosimetry Calculation for shielding and rad. protection in facilities

The FLUKA voxel geometry anthropomorphic phantom It is possible to describe a geometry in terms of “voxels”, i.e., tiny parallelepipeds (all of equal size) forming a 3-dimensional grid You can import a CT scan to a FLUKA Voxel Geometry Now available the official ICRP Human Phantom ICRP Publication 110: Adult Reference Computational Phantoms - Annals of the ICPR Volume 39 Issue 2 7

CT stoichiometric calibration CT segmentation into 27 materials of defined elemental composition (from analysis of 71 human CT scans) Soft tissue Air, Lung, Adipose tissue Skeletal tissue Schneider et al PMB 45, 2000 8

CT stoichiometric calibration (II) Assign to each material a “nominal mean density”, e.g. using the density at the center of each HU interval (Jiang et al, MP 2004) Schneider et al PMB 45, 2000 But “real density” (and related physical quantities) varies continuously with HU value: a HU-dependent correction on density on each voxel is applied

Application in nuclear medicine Radioactive source decay FLUKA contains data about decaying schemes of radioactive isotopes, allowing to select an isotope as radiation source. Complete databases are generated from the data collected from National Nuclear Data Center (NNDC) at Brookhaven National Laboratory.

Application in nuclear medicine Calculation of absorbed dose at voxel level starting from 3D images of activity distribution (SPECT, PET images) Simulations in homogeneous water Simulated 99Tc-SPECT of water phantoms (SIMIND code): Dose calculation: Cylinder + spheres filled with 90Y # 1 # 2

DOSE Maps SPECT/PET - CT images handling VOXEL MONTE CARLO Dosimetry Collaboration INFN and IEO DOSE Maps VOXEL Dosimetry MONTE CARLO 109 particles With 109 particles simulated, FLUKA and VOXEL DOSIMETRY (a standard analytic procedure in nuclear medicine) results in water agree within 5%

Applications in radiotherapy IORT

Simulation of a Linac for RadioTherapy

6 MeV Accelerator –photon fluence

Dosimetric validation

The Leksell Gamma Knife Perfexion: The Leksell Gamma Knife Perfexion (LGK-PFX) is a 60Co based medical device, manufactured by Elekta AB Instruments Stockholm, Sweden. The It is emplyed in the cure of different brain pathologies: small brain and spinal cord tumors (benign and malignant), blood vessel abnormalities, as well as neurologic problems can be fully treated. Fabrizio Cappucci INFN, Milan.

The Leksell Gamma Knife Perfexion: The ionizing gamma radiation is emitted from 192 60Co sources (average activity ~1TBq each). The sources are arranged on 8 identical sectors of 24 elements. The sectors can be placed in correspondence of three different collimation set able to focus the gamma rays on a common spot, called the isocenter of the field, having a radial dimension of about 4, 8 and 16 mm respectively. Fabrizio Cappucci INFN, Milan.

Geometry Modelization: Materials ~ 1350 bodies Protective shield; LEAD. Collimator channels; TUNGSTEN. Gammex 457 Solid Water Isocenter of the field. Radiative sources encapsulated in stainless steel bushings. Thanks to the collaboration with ELEKTA, which provided, under a confidential agreement the detail of the geometry and all the involved material, has been possible to implement an accurate model for the radiation unit. Fabrizio Cappucci INFN, Milan.

Source Modeling: Geometry and materials Metallic bushing. 60Co cylindrical pellets of 1 mm in diameter and 1 mm in length. The β- electron (average energy of about 315 keV) is supposed to be absorbed from the source or the bushing itself, therefore, each MC primary history is composed only by the two photons. Fabrizio Cappucci INFN, Milan.

Relative dose distribution:

Relative dose profiles 16mm X profile 4mm Z profile 8mm Y profile All within acceptance threshold as derived from the Report of the American Association of Physicists in Medicine for stereotactic radiosurgery

Results: We have investigated the relative linear dose distribution along the three coordinated axes. Monte Carlo results have been compared with standard treatment planning provided by Elekta in the same homogeneous conditions of the target. 4∙109 primary histories (total calculation time of about 20h on 26 nodes) have been performed for each simulation.

Relative Output Factors (ROF): ROFs are the ratio between the dose given by a set of collimators and the dose given by the largest collimators, i.e. the 16 mm. Collimator size Elekta ROF FLUKA MC Statistical Error ∆ 8 mm 0.924 0.920 0.88% 0.43% 4 mm 0.805 0.800 0.92% 0.63% Δ is the percentage difference between the results from Monte Carlo calculation and the Elekta values:

Applications in hadrotherapy

Recent Physics Developments Accurate stopping power calculation with all relevant high order corrections Continuous development Interactions of hadrons and nuclei from few tens MeV/u to several hundreds/MeV/u Refiniment of nuclear models for de-excitation, production of relevant isotopes, see P.Sala Varenna 2012, Proc. of int. conf. on Nuclear Reaction Mechanisms. All e.m. physics important for gamma imaging: Compton and annihilation on bound electrons see JINST 2012 JINST 7 P07018 doi:10.1088/1748-0221/7/07/P07018 Other work in progress: interactions of He and light ions… CERN, 10 Jan 2013

Present application of MC calculations in hadron therapy Commissioning of infrastructures Commissioning of Treatment Planning System (TPS in the following) (Heidelberg, CNAO) Calculation of input physics databases (for example: the case of TPS developed within the INFN-IBA collaboration) Check of TP predictions (and possibly provide corrections) Calculation of secondary particle production Data analysis in dosimetry experiments

Example: use of FLUKA @CNAO to provide input databases Beam delivery Scanning with active energy variation Required parameters 147 Energy steps (30-320 mm) 1 Focus size @ ISO FLUKA calculated FWHM at the isocentre as function of the proton beam energy S. Molinelli et. al. Phys. Med. Biol. 58 (2013) 3837 CNAO Med Phys Group

Use of FLUKA @CNAO to provide input databases FLUKA calculated depth-dose distribution in water S. Molinelli et. al. Phys. Med. Biol. 58 (2013) 3837

Dosimetric checks

FLUKA recalculation of a patient PLAN Capability to import a CT scan to build 3D voxel geometry Capability to assigm materials and composition according to HU numbers from CT scan (now automatic!) Capability of coupling to radiobiological models based on Dual Radiation Approach Theory  Calculation of RBE-weighted dose (DRBE)

Treatment planning and Monte Carlo Currently treatment planning for hadron therapy are commonly based on fast analytic dose engines using Pencil Beam algorithms. MC calculation of doses and fluences are superior in accuracy because they take into account heterogeneities, large densities, geometry details. They can predict secondary particle production. However they require much longer execution times…

Towards a new TPS approach based on MC Can we build a TPS using the accuracy achievable by a detailed MC calculation? An integrated MC+optimization tool: to explore the possibility of a treatment planning which overcomes the “water-equivalent” approach to take into account all details about geometry and materials which can be applied to realistic treatment conditions with acceptable CPU time That can be applied in planning for ions with 1<Z<8: today’s talk will be focused on protons only

Components and program flow

A 3-port chordoma case The Syngo TPS prescription MC fw simutation of A. Mairani et al. PMB 58 (2013) 2471 MC fw simutation of TPS prescription Result of our MC Optimization

QA in hadrontherapy Use of detection of b+ activity (PET) or of prompt g’s (or charged particle) produced in the patient. MC is the only possible tool to achieve a reliable prediction of the observables. In the literature: Potentiality of FLUKA: F. Sommerer et al Phys. Med. Biol. 54 2009 K. Parodi et al. pioneered the application of PET as a tool to check hadrontherapy treatments comparing measurements with FLUKA Work going on to achieve a true “in-beam” application of the technique to minimize problems such as metabolic washout

The case for prompt g (nuclear de-excitation) Large flux, maybe enough stats for in-beam Collimation like Anger camera in SPECT Well known technique, robust, compact Wide g energy spectrum  careful design Neutron background rejection? TOF not so easy to exploit. Collimation reduces stats

GANIL: 90 deg photon yields by 95 MeV/n 12C in PMMA Blue: Fluka Red: data Green: dose profile Photon yield E> 2 MeV, within few ns from spill Z (mm) [sketch and exp. data taken from F. Le Foulher et al IEEE TNS 57 (2009), E. Testa et al, NIMB 267 (2009) 993. exp. data have been reevaluated in 2012 with substantial corrections] ENVISION WP6, June 2013

Photon yields by 160 MeV p in PMMA: final NaI detector PMMA target Pb Collimator Schematic layout (dimensions mm) from J.Smeets et al., IBA

Photon yields by 160 MeV p in PMMA: final Energy spectrum of “photons” after background subtraction (collimator open – collimator closed) for 160 MeV p on PMMA. FLUKA red line (with exp. resolution folded in), data black line (J.Smeets et al., IBA, ENVISION WP3) Absolute comparison

Univ. Pisa, Roma, Torino and INFN Project in collab. with CNAO Agreement with CNAO to build a Full in-beam (full-beam) PET system able to sustain annihilation and prompt photon rates during the beam irradiation. FLUKA strongly used for the design

The FLUKA interface: importing DICOM files Vasilis.Vlachoudis@cern.ch Dicom sets Slices Slice Information

2D projections 3D

FLUKA interface: superimposing results to CT images Dose 2 Beams b+ Activity 1 Beam g Emission Map 1 Beam

New tool for PET detector simulation Generation of PET scanner geometry and management of FLUKA output and signal reconstruction

Development of new facilities The TOP-IMPLART Project Usingf a linac for proton-therapy: Introduction of the use of FLUKA in shielding calculation (S. Muraro)