Development of a Dose Profiler for range monitoring in particle therapy - Università degli studi di Roma "La Sapienza" Dottorato di ricerca in ...
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Università degli studi di Roma “La Sapienza”
Dottorato di ricerca in Fisica, XXX ciclo
Development of a Dose Profiler for range
monitoring in particle therapy
Ph.D. candidate: Giacomo Traini
Supervisor: Prof. Riccardo Faccini
02/02/2016
Outline
●
What is Particle Therapy (PT) ?
●
Dose monitoring techniques
●
Development of Dose Profiler
●
Ph.D. thesis plan
02/02/2016 Giacomo Traini – Dottorato in Fisica 2
XXX ciclo
Particle Therapy
●
Beams of accelerated
charged ions (p, 12C) for
cancer therapy
●
Pro: better accuracy in dose
release and cancer cells
killing power with respect to
conventional radiotherapy (X-
rays)
●
Cons: expensive costs
●
More than 50 facilities all CNAO (Centro Nazionale di Adroterapia
Oncologica) facility, Pavia
over the world
02/02/2016 Giacomo Traini – Dottorato in Fisica 3
XXX ciclo
Physics bases: Bethe-Bloch
02/02/2016 Giacomo Traini – Dottorato in Fisica 4
XXX ciclo
Dose released: Bragg peak
D.Schardt T.Elsasser, Rev. Mod. Phys., 82, (2010)
●
Highly localized dose deposition, in a
region named Bragg Peak (BP)
●
Depth of BP depends on the energy
of the particles, and density of the
crossed medium
12
PT ( C) Radiotherapy (photons)
●
PT allows to preserve healty
tissues and organ at risk (OAR)
around tumor
M.Durante and J.S.Loeffler, Nat. Rev. Clin. Oncol., 7, 37-43 (2010)
02/02/2016 Giacomo Traini – Dottorato in Fisica 5
XXX ciclo
RBE
Relative Biological Effectivness
●
Depend on LET (Linear Energy
Transfer) of the radiation
●
Photon irradiation producing free-
radicals, inducing the cells damage
mostly in an indirect way
●
Charged ions induce direct
damages to the DNA
Convenient for treatment of radioresistent tumors
02/02/2016 Giacomo Traini – Dottorato in Fisica 6
XXX ciclo
Uncertainty on dose released
●
Resolution of CT images
●
Morfologic changes occurring
during the treatment
●
Mispositioning of patient
A novel on-line monitoring
technique is required to
Undesired dose
fully profit from the therapy
Tumor region deposited on healthy tissues spatial selectiveness
02/02/2016 Giacomo Traini – Dottorato in Fisica 7
XXX ciclo
Monitoring techniques
●
Problem: particles of the primary beam
don't escape from the patient!
●
Possible approach: use secondary
radiation produced by strong interaction
with target nuclei
● γ-PET:511 keV pair photons generated by the annihilation of the positrons of β+
emitters produced in the fragmentation process
● γ-Prompt: photons emitted by nucleus de-excitation (1-10 MeV)
●
Charged particles : produced by projectiles or target fragmentation
EMISSION POINT OF SECONDARIES IS CORRELATED WITH DOSE DISTRIBUTION AND BP
02/02/2016 Giacomo Traini – Dottorato in Fisica 8
XXX ciclo
γ-PET monitoring
●
Offline PET-scan
Beam: 12C 220 MeV/u
Target: PMMA ● β+ emitters: 11C (τ ~ 30 min), 10C, (τ
~ 10s), 15O (τ ~ 3 min)
LIMITATIONS
●
Low activity with respect to
Beam: p 110 MeV
conventional PET
Target:: PMMA
●
Metabolic wash-out
●
Online extension: large
background of neutral particles
K.Parodi et al., IEEE TNS, Vol. 52, N. 3, (2005)
(n, γ)
02/02/2016 Giacomo Traini – Dottorato in Fisica 9
XXX ciclo
γ-Prompt monitoring
●
Characteristic emission time ~ ns
Beam: 12C 73 MeV/u ●
Energy spectra (1-10 MeV)
Target: PMMA
●
High statistic both for p and 12C
●
Correlation between BP and γ-prompt
emission region
LIMITATIONS
● Background: n and uncorrelated γ
produced by n, site specific
●
Very low efficiency: use of collimators
or compton-camera to reconstruct the
Dose released
origin of the photon
P. Testa et al. “Dose profile monitoring with carbon ions by means of prompt-γ measurements”, Nuclear Instruments and Methods in Physics Research B 267 (2009),
pp. 993–996
02/02/2016 Giacomo Traini – Dottorato in Fisica 10
XXX cicloCharged fragments monitoring
●
Mostly p, but also D,T
●
Larger production at forward angles with
12
Beam: C 220 MeV/u respect to the beam direction
Target: PMMA
●
Correlation between BP and charged
particles emission region
●
Easy reconstruction with a tracker
L. Piersanti et al. - Phys. in Med. And Biol., vol. 59, no. 7, p. 1857, (2014)
LIMITATIONS
●
Low statistic with respect to
PMMA entrance BP
prompt photons
●
Resolution worsen by multiple
scattering
02/02/2016 Giacomo Traini – Dottorato in Fisica 11
XXX cicloDose Profiler development
x-y
384 scintillating fibers
Trac ker Calo rime ter view
500µm x 500 µm
(scintillating fibers) (LYSO 4x4 matrix)
20 cm
84 3
Pixellated LYSO coupled
\ With multi-anode 500scinti
µm llat
PMTs x 5 ing
f 00 ib
µm e rs
20
20
5 cm
cm
cm
1 cm
Fibers coupled to
Hamamatsu SiPMs ~ 2 cm 2.5 cm
(not in scale)
1 mm2
02/02/2016 Giacomo Traini – Dottorato in Fisica 12
XXX cicloDose Profiler aim
Designed and optimized for charged particles tracking, but also capable
to reconstruct the direction of prompt photons
Kinematic of a Compton interaction of prompt
photon in the fibers reconstructed.
Track reconstructed selecting fired fibers
and energy deposited in the calorimeter
02/02/2016 Giacomo Traini – Dottorato in Fisica 13
XXX cicloINSIDE project
Development of a multimodal in-beam dose monitoring system able to detect at the same
time back-to-back gammas from β+ annihilation and charged particles
PET
head s
Trac ker
The DP will be tested and finally installed in
the treatment room of CNAO
Calo rime ter
02/02/2016 Giacomo Traini – Dottorato in Fisica 14
XXX cicloDP expected performances
Monte carlo simulation Proton position resolution
- Beam 12C 220 MeV/u
- Target: PMMA cylinder r = 2.5 cm
- Distribution of secondary protons generated
with a parametrized generator based on
experimental data.
σx ~ 4mm σy ~ 4mm
- Track reconstructed with χ and Kalman
2
filter to taking into account multiple
scattering x_MC - x_rec (cm) y_MC - y_rec (cm)
σz ~ 3mm
z_MC - z_rec (cm)
02/02/2016 Giacomo Traini – Dottorato in Fisica 15
XXX cicloMy Ph.D. thesis
02/02/2016 Giacomo Traini – Dottorato in Fisica 16
XXX cicloDP read-out and DAQ
Front-end
board
Custom More than
ASIC for 4000 total
SiPMs channels
readout
02/02/2016 Giacomo Traini – Dottorato in Fisica 17
XXX cicloTest of front-end board
●
Test of first prototype of front-end board
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192 SiPM, 6 BASIC32
●
Check of the board functionality: Raspberry Pi system
SETUP
SiPMs BASIC
02/02/2016 Giacomo Traini – Dottorato in Fisica 18
XXX cicloTest of ASICs
Plugged to V1495
Vacuum pick-up
system
BASIC32_ADC Antistatic wrist strap
CAEN V1495: includes an FPGA that provides ASIC
Configuration and DAQ
02/02/2016 Giacomo Traini – Dottorato in Fisica 19
XXX cicloTrigger & DAQ development
CALORIMETER
BASIC
FPGA CONCENTRATOR
BASIC
BASIC TRIGGER
X 16 LOGIC
BASIC
BASIC
TO BASICs
BASIC
TRIGGER ---->BASIC read-out enable
X 16 (tracker)
02/02/2016 Giacomo Traini – Dottorato in Fisica 20
XXX cicloFuture steps
●
Development of DAQ, programming the firmware of
FPGAs. Test the FPGA board with a specific
experimental setup
●
Preliminary cosmic ray measurement: evaluation of
efficiency, cross talk
●
Test-beams of the complete system: the
achievement is a very accurate calibration of the
device. In fact, in preparation for a clinical
application in a PT at CNAO, a very high reliability on
the performances of the DP is strongly required
02/02/2016 Giacomo Traini – Dottorato in Fisica 21
XXX cicloSummary
●
Particle therapy is an emerging technique that exploits
charged ions for cancer therapy
●
A monitoring device is strongly needed for the quality control
and improvement of the treatments
●
A novel detector name Dose Profiler, that exploits charge
secondary fragments produced at large angles with respect to
the beam direction, is currently under development
●
Goals of my Ph.D. :
- Realization and test of the DAQ system
- Preliminary cosmic ray test.
- Test-beam measurement, accurate calibration of the detector
- Test at CNAO for pre-clinical application
02/02/2016 Giacomo Traini – Dottorato in Fisica 22
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