1. INFN Pisa tasks Development of a PET system
Dual head, planar; 10 cm x 10 cm FOV
Evaluation of the PET technique with proton and carbon ion irradiations

2. Previous work: The DoPET project (Dosimetry Positron Emission Tomography)
Two planar heads, each with an active area of 45 mm x 45 mm
Distance between the heads: 5+5 cm, 7+7 cm, cm (for phantoms study) and 5+15 cm (for eye monitoring)
18 mm sono 1,5 lunghezze di radiazione
LYSO crystal matrix, 21 x 21 pixels mm x mm each (Hilger Crystals)
Crystal thickness: 18 mm
64-anode PMT (Hamamatsu)
“multiplexed” read-out electronics: 64-inputs/4 outputs

3. The experiments with the Solid Water Phantoms
Phantom Chemical Composition
ρ g/cm3 wH wC wN wO
wCl
wCa SW
1.046
8.02
67.23
2.41
19.91
0.4
2.31
Irradiation and Imaging ID
Dose
TIrr(s)
TDelay(s)
TFrame(m) #1 30
51.3 20 #2 15
31.7 #3 10
16.9 #4 5
9.7

4. Recontructed Activities in the phantom central slice
Extrapolating and Comparing depth-activity profiles …

5. What about the 50% and 20% activity
Dose reduction and activity evaluation …
What about the 50% and 20% activity
fall-offs agreements?

6. … distal 50% and 20% fall-offs positions (for each measurement) have been evaluated in the whole irradiated volume, and results compared:
30 Gy
15 Gy
10 Gy
5 Gy
50%
(31.4 ± 0.2) mm
(31.2 ± 0.3) mm
(31.2 ± 0.6) mm
(31.5 ± 0.6) mm
20%
(33.8 ± 0.3) mm
(33.9 ± 0.5) mm
(34.3 ± 0.7) mm
TFrame=20 min
Dose reduction seems not to influence heavily the accuracy in the extrapolation of reference positions along activity gradients.
What the TFrame effect? Let’s consider the 5 Gy Irradiation..
TFrame≈1 m
TFrame≈2 m
TFrame≈3 m
TFrame≈6 m
TFrame≈11 m
TFrame≈20 m
50%
(29.9 ± 1.9) mm
(30.5 ± 1.6) mm
(31.2 ± 1.2) mm
(31.6 ± 0.7) mm
(31.5 ± 0.6) mm
20%
(35.1 ± 2.4) mm
(35.1 ± 2.3) mm
(35.2 ± 2.0) mm
(34.5 ± 1.0) mm
(34.5 ± 0.8) mm
(34.3 ± 0.7) mm
TDelay=0
1.8x105 true coincidences detected
Irradiated volume:~10 cm3

7. For exact activity (Dose) evaluation a time analysis on the measured data is necessary in order to correct for the decay of the produced isotopes.
The separation of isotope contributions is made as follows:
For any voxel of the reconstructed image the behaviour in time (e.g. 5 time frames) is fitted with a multiple exponential decay law: A = SAXi e^(t/tXi) where Xi are all of the possible isotopes that can be produced in the material, e.g. for solid water we have 11C and 15O only.
Along the central axis...

8. Aborfazl Arabpour

9. Final objective for end 2011 TPS project PET monitoring prototype
Use of 4 modules vs. 4 modules of LYSO + H8500
10 cm
2D view of the FOV coverage of the 4+4 modules
10 cm
Matrix size: 23 x 23 pixels
1.9 mm side, on a 2.0 mm pitch
Thickness: 18 mm.

10. Ongoing development toward the final DAQ
DoPET
1 vs. 1 module
5 cm x 5 cm active area
Fully characterized
Plug’n’PET dual
2 vs. 2 modules
5 cm x 10 cm active area
New modular approach
Will be tested on next July BTU
Plug’n’PET
Up to 9 vs. 9 modules
With 4 vs 4 modules installed (10 cm x 10 cm active area) will be tested in the following BTUs ✔
(2009/2010)
July 2010
Next BTUs

11. Acquisition system architecture
LYSO1A
Anger-like signals
LYSO2A
PMT 1A
LYSO3A
DAQ 1A
PMT 2A
LYSO4A
DAQ 2A
PMT 3A
DAQ 3A
PMT 4A
CFD
DAQ 4A
CFD
CFD
CFD
Timing signals
MAINBOARD
Master FPGA
coincidence triggers
USB Controller
DAQ 1B
Timing signals
Host PC
DAQ 2B
CFD
DAQ 3B
CFD
CFD
DAQ 4B
PMT 1B
PMT 2B
CFD
PMT 3B
LYSO1B
PMT 4B
LYSO2B
LYSO3B
LYSO4B
Anger-like signals

12. Timing signal improvement
Potential advantages:
Improvement in timing
As required for using a narrower timing window
Improvement in count rate performance
By reducing the dead time

13. Next measurements
Evaluate the impact of the increased detection efficiency with the new larger system on proton beams
4 vs 4modules (10 cm x 10 cm total area)
2 ns coincidence window
Evaluate the system performance in clinical conditions (10-15 Gy, 20 cm head distance)
maximum particle range measurement
quantitative dose estimation

14. Next measurements
Evaluate the capability of the PET system with carbon ion beams
Particle range measurement capability
Comparison of the carbon beam result with MC
Experimental validation of the filtering approach for dose monitoring with carbon ion beams

15. Pisa Manpower

16. Funds request 2011 Missioni Interne 9.0 Missione Estero 5.0 Consumo
Capitolo di spesa
Richieste (kEuro)
Richieste s.j. (kEuro)
Missioni Interne
9.0
Missione Estero
5.0
Consumo
4.0
Inventario
3.5
Trasporti
2.0
Totale
21.0