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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
Developed and maintained under an INFN-CERN agreement Copyright 1989-2013 CERN and INFN
http://www.fluka.org
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
>5000 users
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
Regions of high losses(e.g., Collimators,…)
ATLAS
Regions with low losses(e.g., due to residual gas)
The LHCLoss Regions
Point 1
Point 2
Point 3.2
Point 3.3
Point 4 Point 5
Point 6
Point 7
Point 8
ALICE
LHCb
MomentunCleaning
RF CMS
LHC Dump
BetatronCleaning
Application for medicine: some examples
• Nuclear Medicineo Dosimetry
• Radiotherapyo Simulation of therapy devices o Check of treaments
• Hadrontherapyo Commissioning of facilitieso Treatment planning and forward checkso Predictions for monitoring applications (imaging for
hadrontherapy)o Design of instruments, dosimetryo Calculation for shielding and rad. protection in facilities
The FLUKA voxel geometry
7
anthropomorphic phantom
Now available the official ICRP Human PhantomICRP Publication 110: Adult Reference Computational Phantoms -
Annals of the ICPR Volume 39 Issue 2
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 importa CT scan to a FLUKA Voxel Geometry
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
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
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.
Radioactive source decay
Application in nuclear medicineCalculation of absorbed dose at voxel level starting from 3D images
of activity distribution (SPECT, PET images)
Simulated 99Tc-SPECT of water phantoms (SIMIND code):
Dose calculation: Cylinder + spheres filled with 90Y
Simulations in homogeneous water
# 1 # 2
SPECT/PET - CT images handling
VOXELDosimetry
MONTE CARLO109 particles
DOSE Maps
With 109 particles simulated, FLUKA and VOXEL DOSIMETRY (a standard analytic procedure in nuclear medicine) results in water agree within 5%
Collaboration INFN and IEO
Applications in radiotherapy
IORT
Simulation of a Linac for RadioTherapy
15
6 MeV Accelerator –photon fluence
Dosimetric validation
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 CappucciINFN, 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 CappucciINFN, Milan.
The Leksell Gamma Knife Perfexion:
Protective shield; LEAD.
Collimator channels;TUNGSTEN.
Isocenter of the field.
Radiative sources encapsulated in stainless steel
bushings.
Gammex 457 Solid Water
Fabrizio CappucciINFN, Milan.
Geometry Modelization: Materials
~ 1350 bodies
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.
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 CappucciINFN, Milan.
Source Modeling: Geometry and materials
Relative dose distribution:
All within acceptance threshold as derived from the Report of the American Association of Physicists in Medicine for stereotactic radiosurgery
16mm X profile
8mm Y profile
4mm Z profile
Relative dose profiles
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.
Results:
Δ is the percentage difference between the results from Monte Carlo calculation and the Elekta values: 100% · 1-
FLUKA
ELEKTA
OF
OF
Collimator size
ElektaROF
FLUKAROF
MC Statistical
Error∆
8 mm 0.924 0.920 0.88% 0.43%
4 mm 0.805 0.800 0.92% 0.63%
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.
Applications in hadrotherapy
Recent Physics Developments
27CERN, 10 Jan 2013
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…
Present application of MC calculationsin 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
Required parameters 147 Energy steps (30-320 mm)
1 Focus size @ ISO
Beam delivery
Scanning with active energy variation
FLUKA calculated FWHM at the isocentre as function of the proton beam energy
CNAO Med Phys Group
S. Molinelli et. al.Phys. Med. Biol. 58 (2013) 3837
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?
• 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
An integrated MC+optimization tool:
Components and program flow
A 3-port chordoma case
The Syngo TPS prescription
MC fw simutation of TPS prescription
Result of our MCOptimization
A. Mairani et al. PMB 58 (2013) 2471
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
ENVISION WP6, June 2013 39
GANIL: 90 deg photon yields by 95 MeV/n 12C in PMMA
Blue: FlukaRed: dataGreen: dose profileP
hoto
n y
ield
[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]
E> 2 MeV, within few ns from spill
Z (mm)
NaI detector
PMMAtarget
Pb Collimator
Schematic layout(dimensions mm) from J.Smeets et al., IBA
Photon yields by 160 MeV p in PMMA: final
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
2D projections
3D
FLUKA interface: superimposing results to CT images
Dose2 Beams b+ Activity
1 Beam
g g Emission Map1 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)
