Riunione TOPEM Bologna 10-03-2010
- ore 11:00 - 11:45
F. Garibaldi - Introduzione e stato dell'arte dell'esperimento
- ore 11:45 - 12:30 A. Gabrielli - Presentazione della catena HPTDC-NINO su crate VME in laboratorio.
- ore 12:30 - 13:30 P. Musico - AOB Genova
- ore 13:30 - 14:30 Pausa Pranzo- ore 14:30 - 15:15 F. Loddo - AOB Bari
Topem: Stato dell’arte
F,Garibaldi – Bologna 10-03-2010
 L’esperimento: perche’ e come
 Challenges/problems
 A che punto siamo
(qualche risultato preliminare(Roma,Bari/Ct,Lns)
 Next steps
 Interazione con referees
 Richiesta fondi integrativi?
Prostate cancer is the most common cancer and the second leading cause of cancer death
PSA
SENSITIVITY 83%
SPECIFICITY 17%
CT
Selective indication :
 PSA > 10 ng/ml
 cT3

Gleason score > 7
PSADRETRUS
biopsy
diagnosis is made from tissue obtained on a blind biopsy
Need to consider fundamental changes in the approach to diagnosing
prostate cancer
In the future, multimodality imaging approach tailored to each patient
PET/MR Design Challenges
•
Limited space for the PET detector
•
PET detector must not use magnetic materials

•

Could distort MR image
MR gradient field-eddy currents

Could produce noise in detector

Could heat detector
MR RF transmit


Could produce MR image artifacts
MR-compatible PET shielding materials


Could distort MR image
PET detector must not emit in MR frequency

•
MRI & MRS
Could produce false PET events
MR materials

Will produce more gamma attenuation
-CITRATE that is present in the normal prostate
-CREATINA that may increase in the phlogosis and
all the proliferative processes
-COLINE more specific for a neoplastic
transformation
Dedicated high resolution high sensitivity PET probe for prostate imaging
Requirements for radionuclide imaging
- radiotracer (high specificity)
- high sensitivity
- practical consideration, cost
-
Detector goals
3D photon position capability
spatial resolution ~ 1mm
high coincidence photon efficiency
energy resolution ~ 12% or better
TOF ~ 300 ps or better
drawback of the standard PET
-
detectors far away from prostate
poor spatial resolution (6 – 12 mm)
poor photon detection efficiency (<1%)
activity ouside the organ
-> poor contrast resolution
- relative high cost per study
Dedicated PET detector ring
(Moses)
Better than standard scannner but still limited.
- Endorectal probe: PET coupled to a dedicated detector or to a standard PET
scanner
huge background
from the bladder
!!
Could
we
reduce
or
eliminate it?
6
Resolution (mm FWHM)
5
4
3
3 mm
2 mm
2
1
0
Probe resolution = 1mm FWHM
0
5
10
15
20
25
Distance from probe face (cm)
30
35
40
TOF provides a huge
Performance Increase!
nconv= D/d
Signals from Different Voxels are Coupled
 Statistical Noise Does Not Obey
Counting Statistics
If there are N counts in the image,nTOF=Δx/d
N
SNR = N
Timing resolution depends on
path))
-
scintillator (kind (n.of photons, decay time, geometry (light
photodetector (time jitter, capacitance, PDE etc)
coupling (light collection efficiency)
electronics (in our case has to be very compact  ASIC)
- front end
- readout architecture
Surti, Karp et al. LaBr3
A big advantage of SiPMs in a fast timing is
a low time jitter, below 100 ps. However, a
fast timing is limited by rather low photon
detection efficiency (PDE), not exceeding 10
– 20%, depending on the number of pixels.
This is of particular importance in timing
with slow scintillators, like LSO, with the
decay time constant of about 40 ns. Thus
the expected time resolution is a direct
function of sqr(n.p.e.) (PDE of SiPM). Thus,
the application of SiPMs to TOF PET
detectors requires a number of optimizations
related to the size of the device, its PDE,
number of pixels and finally its capacitance.
Mozsynski
Endorectal (SPECT and) PET [(2.5 x 5
(6) mm2] probe in multimodality with MRI
Array SiPm
DOI
≈1.5 mm
S. Majewski
[1(2) x 1 (2)] x [4 (5) x 4(5)] (5) cm3
S. Majewski
0T
7T
LYSO (LSO) vs LaBr3(Ce)
- Pixellated (not available for LaBr3(Ce)) vs continuous (dependence on layout)
- Availabilty of LaBr3(Ce)
- Balancing “isolation” of prostate from bladder vs SNR (NECR)
Low Density  Radial
Elongation
Penetration Blurs Image
Resolution vs. Position
3 Attenuation
Lengths
Resolution (mm fwhm)
20
LaCl3
NaI
15
LaBr3
BaF2
RGB
LuI
3
10
LuYAP
LSO
LuAP
GSO
BGO
5
0
0
5
10
15
20
25
Radial distance (cm)
Some Degradation with LuI3, More with Ce/LaBr3
Fraction
 Low Coincidence
Both Photons Deposit >350 keV
Efficiency
Compton
3 Atten.
Lengths
Scintillator
Photoelectric
LaCl3
NaI
RGB
LaBr3
BaF2
LuI3
GSO
LuYAP
LSO
LuAP
BGO
0
0.2
0.4
0.6
0.8
1
Relative Efficiency
Some Degradation with LuI3, More with Ce/LaBr3
Coincidence Timing
Resolution
BaF2
210 ps
Scintillator
RGB
330 ps
LaCl3
265 ps
LaBr3
260 ps
LuI3
200 ps
LSO
300 ps
LuAP
360 ps
BGO
3000 ps
0
100
200
300
400
500
Coincidence Timing Resolution (ps)
• New Scintillators Capable of Time-of-Flight
• 500 ps Resolution  5x Reduction in Noise Variance
suddivisione compiti
- Bari
- Ranieri: ASIC
- De Leo (coll. con CT (e Lecce))
- Bologna
- scheda ibrida per timing (coll. con Genova)
- Genova
- scheda ibrida timing (coll con Bologna)
- LNS
- caratterizzazione SiPM (PDE etc)
- timing con SiPM
- Roma
- caratterizzazione SiPm (Meddi)
- misure con minidetectors (Garibaldi)
- simulazione (collaborazione con Cagliari (?) e Genova (?))
- PET/MRI: Maraviglia e coll.
Roma (Meddi). Caratterizzazione SiPM IRST
Roma. F. G.
- simulazione: pending… (installato Geant4, (e Gate), codice Geant4 per
prostata da Neal Clinthorne. Collaborazione possibile con Viviana Fanti
(Cern/Cagliari), e Genova?
- da fare: misure “di base” con mini-rivelatori
- LYSO continuo e pixellato ( 1 x 1 mm2, 3 x 3 mm2) accoppiati
a SiPM Hamamatsu 4 x 4 (3x3 mm2), Misure DOI con 10 mm
e
5 mm di spessore (sandwitch). Readout disponibile,
interfaccia
per SiPM (Paolo).
- scintillatori, prima meta’ Aprile, 1 array SiPm Hamamatsu
gia’ disponibile
- readout: interfaccia Paolo
- primo minidetector in funzione  test in MRI (con e senza
screening (rame). (verifca effetto PET su MRI)
Catania-Bari: misure di timing con pmt veloci
TOPEM: attività prevista del gruppo INFN-LNS
•
•
•
•
•
•
•
•
•
•
Strumenti disponibili:
Laser pulsato 40ps 408nm
Laser pulsato 40ps 650nm
Sorgenti radioattive
Camera oscura
Sfera integratrice
Cella peltier & dito freddo
Amplificatore di tensione Gain=200,
4GHz
Oscilloscopio digitale 4GHz
Sistema di DAQ multiparametrico
ADC, QDC, TDC, Scaler
•
•
•
•
•
•
•
•
•
•
•
Misure da effettuare su SiPM:
Dark noise & cross-talk
Gain
Timing con laser
Risoluzione energetica con laser?
(se fattibile)
PDE (2 punti, 408nm e 650nm)
Timing con scintillatore (1 SiPM +
laser)
Timing in coincidenza con scint. (2
SiPM + 22Na)
Timing vs temperatura
Time walk
Risoluzione energetica con
scintillatore (22Na, 137Cs)
altro.....
LNS : Cosentino-Finocchiaro
1mm x 1mm
testati 24 campioni
1mm x 1mm
testati 24 campioni
1mm x 1mm
testati 4 campioni
1mm x 1mm
testati 4 campioni
spettri in carica con luce laser,
a tre diverse intensità
Bilancio 2010 > Riunione Assegnazioni > Gruppo V > Esperimento TOPEM > Verbale riunione
Verbale del Referee
L_esperimento intende realizzare un nuovo sistema di imaging della prostata, basato su un rivelatore PET in combinazione
con una MRI di tipo endorettale. La tecnica proposta intende risolvere gli attuali problemi diagnostici del cancro della prostata
attraverso un rivelatore PET in grado di migliorare efficienza e risoluzione spaziale dell_imaging prostatico dopo la
somministrazione di Colina radiomarcata C11. L_immagine funzionale combinata con MRI ad alta risoluzione dovrebbe
migliorare in modo consistente il valore prognostico. Il finanziamento proposto avvia un primo studio di fattibilit_ articolato in
quattro punti: a) realizzazione di un rivelatore PET composto da due testate delle dimensioni di circa 2 x 2 cm2 con cristalli
pixellati di LYSO/LSO e lettura della luce di scintillazione mediante array di SiPM; b) verifica della sua compatibilita_ con
MRI mediante test degli effetti del campo magnetico sull_imaging PET e degli effetti dell_apparato PET sull_ imaging MRI; c)
studio della coincidenza temporale con SiPM per valutare i vantaggi della tecnica ToF sull_imaging prostatico; d)
progettazione di un front-end integrato per la lettura e l_analisi timing dei SiPM. La Commissione ritiene che i risultati dello
studio di fattibilita_ siano vincolanti ai fini del prosieguo dell_esperimento. Data la necessit_ di integrare fra di loro parti
complesse (SiPM, FE chip, readout) la Commissione chiede alla collaborazione di indicare un Technical Coordinator che
presenti un documento descrittivo del sistema per maggio 2010. referees: Aloisio, Pani, Del Guerra, Greco, Ambrosi
Commento del Resp. Nazionale
Electronics
Individual Channel Electronics:
Anger Logic:
IDE AS VA-TA chip based, multiplexed readout
1024 Ch.
~ 2 kHz
Resistive Chains


phototube

crystal
Resistive chain and
output signals
Cristal and Phototubes,
Planar view



Higher Sensitivity
Lower channel-to-channel crosstalk
 better signal quality
Great flexibility in processing data
Enhanced data
Complexity
Speed
High Cost
4096 ch at 10 KHz
Gamma Emission posizion (X,Y) obtained with:
N ch a n n el
X 
X  X
ZX

Z
X

;Y 
Y
Y Y

Z
Y

X 
c X
i
i 1
N ch a n n el
c
i 1
i
N ch a n n el
i
;Y 
c Y
i i
i 1
N ch a n n el
c
i 1
i
ci  i th channel signal
(X i , Yi )  i th channel position
Low Density  Radial
Elongation
Penetration Blurs Image
Resolution vs. Position
3 Attenuation
Lengths
Resolution (mm fwhm)
20
LaCl3
NaI
15
LaBr3
BaF2
RGB
LuI
3
10
LuYAP
LSO
LuAP
GSO
BGO
5
0
0
5
10
15
20
25
Radial distance (cm)
Some Degradation with LuI3, More with Ce/LaBr3
Fraction
 Low Coincidence
Both Photons Deposit >350 keV
Efficiency
Compton
3 Atten.
Lengths
Scintillator
Photoelectric
LaCl3
NaI
RGB
LaBr3
BaF2
LuI3
GSO
LuYAP
LSO
LuAP
BGO
0
0.2
0.4
0.6
0.8
1
Relative Efficiency
Some Degradation with LuI3, More with Ce/LaBr3
Coincidence Timing
Resolution
BaF2
210 ps
Scintillator
RGB
330 ps
LaCl3
265 ps
LaBr3
260 ps
LuI3
200 ps
LSO
300 ps
LuAP
360 ps
BGO
3000 ps
0
100
200
300
400
500
Coincidence Timing Resolution (ps)
• New Scintillators Capable of Time-of-Flight
• 500 ps Resolution  5x Reduction in Noise Variance
For SPECT:
Conclusi
ons
• CeBr3 and LaBr3 are compelling
– Better light output & energy resolution than NaI:Tl
– Shorter attenuation length than NaI:Tl
– No other performance drawbacks!
For PET:
• LuI3 is very interesting, but has some tradeoffs
– Energy resolution, light output, & timing excellent
– Worse attenuation length & photoelectric fraction
• LaBr3 and CeBr3 have more severe tradeoffs
– Atten. length & photoelectric fraction much worse
Economic Growth is Absolutely Necessary