PET with Resistive Plate Chambers (RPC-PET) P.Fonte

1. PET with Resistive Plate Chambers (RPC-PET) P.Fonte Contributors DFUC: Custódio Loureiro, Paulo Gordo ESTSP: Filomena Clemêncio GSI: Michael Traxler ICNAS: Ângela Cruz, Antero Abrunhosa, Francisco Oliveira, José Sereno LIP: Afonso Bernardino, Alberto Blanco, Américo Pereira, Carlos Silva, Joaquim Oliveira, Luís Lopes, Nuno Carolino, Orlando Cunha, Paulo Martins, Rui Alves LIP/DFUC: Paulo Crespo, Rui Ferreira Marques LIP/IPC: Miguel Couceiro, Paulo Fonte, U.Frankfurt: Jan Michel U.J.Kracow: Marek Palka, Grzegorz Korcyl, Marcin Kajetanowicz

2. Outlook • 9’ repetition of the slides of Jornadas 2016 • 1’ upgrade 2016/17

3. Positron Emission Tomography (PET) • Annihilation photons, detected in temporal coincidence (a few ns) by a set of detectors surrounding the patient, are recorded defining a Line Of Response (LOR) • Image is reconstructed from millions of acquired LORs Coincidence processing Transaxial plane Sagittal plane Positron/electron annihilation Image reconstruction

4. S tacked RPCs e- e+ - e .......... - e - e The basic idea for RPC-based TOF-PET The converter-plate principle Use the electrode plates as a g converter, taking advantage of the natural layered construction of the RPCs. [Blanco 2002] Time resolution for 511 keV photons: (our routine lab-test tool) 90 ps s for 1 photon 300 psFWHM for the photon pair Glass Gas A previous work on PET with gaseous detectors(21 lead plates + 20 MWPCs = 7% efficiency) “The Rutherford Appleton Laboratory´s Mark I Multiwire Proportional Counter Positron Camera” J.E. Bateman et al. NIM 225 (1984) 209-231

5. Started a long time ago… Excellent position resolution  small animal PET Affordable in large areas • full-body field of view human PET (not covered in this talk) • Increased sensitivity at physics-limited resolution

6. N Plates Lead Glass Lead-Glass Detection Probability (511 keV Photons) Plate Thickness (m) Bateman et al. N Plates Optimum Thickness (µm) Comparison with GEANT - efficiency Optimum efficiency is balanced by beam absorption (thicker plates) and extraction probability (thinner plates) Optimum thickness depends on the number of plates and on the material. Our measurement: for few gaps ~0.2%/gap @ 511 keV [Blanco 2005]

7. Small animal PET - a first prototype Charge-sensitive electronics allowing interstrip position interpolation Aimed at verifying the concept and show the viability of a sub-millimetric spatial resolution. 32 strips 16 plates ....... ....... 16 stacked RPCs Depth of interaction (now enjoying a second life as an exhibition item) Z 2D measurement of the photon interaction point X Transaxial

8. Proceeding IEEE MIC (2004) M2-177 Image spatial resolution (gaussian fitting) Maximum likelihood-expectation maximization with resolution modeling (ML-EM) ~ 305 m FWHM Filtered Back Projection FBP ~ 465 m FWHM 0.46 0.31 0.47 0.48 0.45 0.30 0.32 0.29 [A.Blanco, IEEE MIC 2004, PhD thesys] Homogeneous spatial resolution over the entire field of view

9. Full scanner for mice – project & calculations Expected quantum efficiency and resolution X We are here Almost 4 coverage

10. Detector & readout HV distribution layer (signal-transparent) kapton insulation 5 gaps 0.35 mm 6 x 0.38mm glass ~5 mm thick Full head

11. Preliminary resolution tests in simplified geometry but realistic readout [P.Martins JINST 2014 + PhD thesys] Two detectors with XY localization Detector a Step Motor Acceptance ±56º Detector b Needle source, 0.2 mm int. Planar (disk) source

12. Preliminary resolution tests in simplified geometry but realistic readout [P.Martins JINST 2014 + PhD thesys]

13. Expected performance vs. other systems [P.Martins JINST 2014 + PhD thesys] Expected performance exceeds the “target”

14. Construction at LIP (2013/14)

15. X’ Resolution in final geometry (2 heads only, needle source) PRELIMINARY Calibration not done in full.

16. Installed at ICNAS (UC) in July 2014

17. First client (31/7/2014) Poor animal resting after 18FDG injection and in the scanner tunnel (The head is central and the heart is at the edge of the field-of-view) • Maximum intensity projection. • The two hot spots in the head are likely the Harderian glands and the heart walls seem resolved

18. Some interesting images of mice Live heart transaxial sections with 18FDG 1 mm2 Harderian glands and left striatum with 11C-raclopride

19. Some interesting images of mice 11C Raclopride (ratinho I)

20. Some interesting images of mice 64Cu ASTM (ratinho G) ( with strong involvement of P.Martins)

21. Some interesting images of mice 64Cu ASTM (recent) Co-registration with MRI (Francisco Oliveira)

22. GUI client to data processing + visualization

23. GUI client to (custom) OSEM image reconstruction server

24. Slow control

25. Daily quality assurance/sensitivity check

26. Enlarged for rats Rats A & B

27. trigger probe  22Na charge time (trigger) charge charge-randoms time (trigger) Efficiency measurement Simulation Best chance at this configuration = 6.7% Less because of dead material (1glass+1PCB electrode/rpc) Observed: Charge = 5.12 % Trigger = 3.60 % GEANT simulation needed + better FEE

28. Work in 2016/17

29. Biology results start to appear Congress of the Portuguese Society of Biochemistry, 2016 Several other studies in the pipeline

30. Upgrade 2016/17 – new DAQ + FEE (v2) HV mess will be also solved… Higher gain trigger DAQ + trigger Comms + Power management Assembled and deployed (hw+sw) by the new member of the RPC group João Saraiva Similar to the systems used for the MASTER and TOMUVOL telescopes

31. Upgrade 2016/17 – new DAQ + FEE (v2) Custom 48 ch charge amp boards with improved isolation 90% of the analog electronics Ample room for more… Noise performance intrinsic: ~0.1 fC (600 e-) In-system: ~1fC (0.5 with expensive FETs)

32. Upgrade 2016/17 – new DAQ + FEE (v2) TRB3 platform developed by the TRB collaboration (trb.gsi.de) Configurable trigger system (C.Loureiro + F.Clemencio) FE ADCaddon (48 ch @ 40MSPS) System: 2 TRBs, 5 ADCs, 5 qFEE boards, 240 ch

33. charge time (trigger) charge charge-randoms time (trigger) Upgrade 2016/17 – improvement on sensitivity Efficiency measurement in v1 ~x2 @ 8000V To be expected ~(5.1/3.6)^2=2.0  satisfactory electronics V1 V2

34. Upgrade 2016/17 – new rat-sized tunnel O velho era impresso e vertia como uma peneira

35. Upgrade 2016/17 – new operator interface + multiuser system (60% done) Current one: shell script + matlab… Browser-server architecture Front-end: html, JS, AJAX, PHP Back-end: matlab Data protection for multiple users Backups etc

36. Summary • More than 200 mice (and 2 rats) examined so far with 11C, 18F, 64Cu for biological research • Operated independently by a team at ICNAS • MRI co-registration via a transfer marker • Experience: detectors flawless; some problems with electronics • At TRL 7 (Technology Readiness Level 7: tested in realistic environment) 2016/17 • First biology results appeared • Sucessfull electronics and mechanics upgrade • Started user-friendly operator interface + multiuser system • PTDC submitted (M.Couceiro) Next 2 years (manpower allowing) • Submit C2020 project in human brain/organs PET • New rat-sized heads = full body for mice • Thorough calibration • Nice standard images (NaF, Raclopride, tumor) • Tests by NEMA NU2 standard • Finish operator interface + multiuser system • Completion of slow control •  TRL 8 (market readiness)