ore 11:00 - 11:45 F. Garibaldi - Introduzione e stato dell'arte dell'esperimento

- 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

Riunione TOPEM Bologna 10-03-2010

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?

PSA SENSITIVITY 83%

SPECIFICITY 17%

CTSelective indication : PSA > 10 ng/ml cT3 Gleason score > 7

diagnosisdiagnosis is made from tissue obtained on a is made from tissue obtained on a blind biopsyblind biopsy

Need to consider fundamental changes in the approach to diagnosing prostate cancer

In the future, multimodality imaging approach tailored to each patient

PSADRETRUS

biopsy

Prostate cancer is the Prostate cancer is the most common cancer and most common cancer and thethe second leading causesecond leading cause of cancer of cancer death death

• Limited space for the PET detector

• PET detector must not use magnetic materials

Could distort MR image

• PET detector must not emit in MR frequency

Could produce MR image artifacts

• MR-compatible PET shielding materials

Could distort MR image

MR gradient field-eddy currents

Could produce noise in detector

Could heat detector

MR RF transmit

Could produce false PET events

MR materials

Will produce more gamma attenuation

PET/MR Design Challenges

-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

MRI & MRS

Requirements for radionuclide imaging- radiotracer (high specificity)- high sensitivity- practical consideration, cost

Dedicated high resolution high sensitivity PET probe for prostate imaging

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 backgroundfrom the bladder !!

Could we reduce or eliminate it?

0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

Distance from probe face (cm)

Re

solu

tion

(m

m F

WH

M)

Probe resolution = 1mm FWHM

2 mm

3 mm

Signals from Different Voxels are Coupled

Statistical Noise Does Not Obey Counting Statistics

Signals from Different Voxels are Coupled

Statistical Noise Does Not Obey Counting StatisticsIf there are N counts in the image,

SNR =

N

N

TOF provides a huge Performance Increase!

nconv= D/d

nTOF=Δx/d

Franco Garibaldi

prova commenti

Timing resolution depends on

- scintillator (kind (n.of photons, decay time, geometry (light path))

- 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

[1(2) x 1 (2)] x [4 (5) x 4(5)] (5) cm3

Array SiPm

Endorectal (SPECT and) PET [(2.5 x 5 (6) mm2] probe in multimodality with MRI

DOI

S. Majewski

≈1.5 mm

S. Majewski

7 T

0 T

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

Resolution vs. PositionPenetration Blurs Image

3 AttenuationLengths

Some Degradation with LuI3, More with Ce/LaBr3Some Degradation with LuI3, More with Ce/LaBr3

0

5

10

15

20

0 5 10 15 20 25

Resolution (mm fwhm)

Radial distance (cm)

BGOLuAPLSOLuYAPGSO

LuI3

BaF2

LaBr3

NaI

RGB

LaCl3

Low Photoelectric Fraction

Low Coincidence Efficiency

Photoelectric Compton

Both Photons Deposit >350 keV

3 Atten.Lengths

0 0.2 0.4 0.6 0.8 1

BGOLuAPLSO

LuYAPGSO

LuI3

BaF2

LaBr3RGB

NaI

LaCl3

Relative Efficiency

Scintillator


Coincidence Timing Resolution

• New Scintillators Capable of Time-of-Flight• 500 ps Resolution 5x Reduction in Noise Variance


0 100 200 300 400 500

BGO

LuAP

LSO

LuI3

LaBr3

LaCl3

RGB

BaF2

Coincidence Timing Resolution (ps)

Scintillator

210 ps

265 ps

260 ps

200 ps

300 ps

360 ps

3000 ps

330 ps

suddivisione compiti

- Roma- caratterizzazione SiPm (Meddi)- misure con minidetectors (Garibaldi)- simulazione (collaborazione con Cagliari (?) e Genova (?))- PET/MRI: Maraviglia e coll.

- 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 (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.....

1mm x 1mmtestati 24 campioni

LNS : Cosentino-Finocchiaro




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, AmbrosiCommento del Resp. Nazionale

Higher Sensitivity Lower channel-to-channel

crosstalk better signal quality

Great flexibility in processing data

Enhanced data Complexity Speed High Cost

ElectronicsIndividual Channel Electronics:IDE AS VA-TA chip based, multiplexed readout

1024 Ch. ~ 2 kHz

Anger Logic:Resistive Chains

Cristal and Phototubes, Planar

view

Resistive chain and output signals

phototube

crystal

−+++−++=

−−+=

−−+=

YYXXZ

Z

YYY;

Z

XXX

Gamma Emission posizion (X,Y) obtained with:

position channel i)Y ,(X

signalchannel ic

c

YcY;

c

XcX

thii

thi

N

1ii

N

1iii

N

1ii

N

1iii

channel

channel

channel

channel

=

=

==

∑

∑

∑

∑

=

=

=

=

4096 ch at 10 KHz

Low Density Radial Elongation

Resolution vs. PositionPenetration Blurs Image

3 AttenuationLengths


0

5

10

15

20

0 5 10 15 20 25

Resolution (mm fwhm)

Radial distance (cm)

BGOLuAPLSOLuYAPGSO

LuI3

BaF2

LaBr3

NaI

RGB

LaCl3

Low Photoelectric Fraction

Low Coincidence Efficiency

Photoelectric Compton

Both Photons Deposit >350 keV

3 Atten.Lengths

0 0.2 0.4 0.6 0.8 1

BGOLuAPLSO

LuYAPGSO

LuI3

BaF2

LaBr3RGB

NaI

LaCl3

Relative Efficiency

Scintillator


Coincidence Timing Resolution



0 100 200 300 400 500

BGO

LuAP

LSO

LuI3

LaBr3

LaCl3

RGB

BaF2

Coincidence Timing Resolution (ps)

Scintillator

210 ps

265 ps

260 ps

200 ps

300 ps

360 ps

3000 ps

330 ps

Conclusions

ConclusionsFor SPECT:

• 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 NecessaryEconomic Growth is Absolutely Necessary

Documents

ore 11:00 - 11:45 F. Garibaldi - Introduzione e stato dell'arte dell'esperimento