1. 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)

2. 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 CERN and INFN
>5000 users

3. 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

4. The Physics Content of FLUKA
60 different particles + Heavy Ions
Nucleus-nucleus interactions from Coulomb barrier up to TeV/n
Electron and μ interactions 1 keV – TeV
Photon interactions 100 eV 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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.

11. 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

12. 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%

14. Applications in radiotherapy
IORT

15. Simulation of a Linac for RadioTherapy

16. 6 MeV Accelerator –photon fluence

17. Dosimetric validation

18. 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.

19. The Leksell Gamma Knife Perfexion:
The ionizing gamma radiation is emitted from Co 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.

20. 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.

21. 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.

22. Relative dose distribution:

23. 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

24. 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.

25. 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:

26. Applications in hadrotherapy

27. 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: / /7/07/P07018
Other work in progress: interactions of He and light ions…
CERN, 10 Jan 2013

28. 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

29. Example: use of FLUKA @CNAO to provide input databases
Beam delivery
Scanning with active energy variation
Required parameters
147 Energy steps ( mm)
1 Focus 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

30. 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

31. Dosimetric checks

32. 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)

33. 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…

34. 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

35. Components and program flow

36. 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

37. 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
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

38. 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

39. 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

40. 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

41. 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

42. 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

43. The FLUKA interface: importing DICOM files
Dicom sets
Slices
Slice Information

44. 2D projections 3D

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

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

47. 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)