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

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, 10+10 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 2.152 mm x 2.152 mm each (Hilger Crystals) Crystal thickness: 18 mm 64-anode PMT (Hamamatsu) “multiplexed” read-out electronics: 64-inputs/4 outputs

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

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

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

… 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

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...

Aborfazl Arabpour

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.

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

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

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

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

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

Pisa Manpower

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