Student: G. A. Fornaro

1. Characterization of diffractive optical elements for improving the performance of an endoscopic TOF-PET detector head Student: G. A. Fornaro Supervisor: G. Battistoni G.A. Fornaro

2. Outline • PET principles • EndoTOFPET-US: the project • Time of light (TOF) principle • Optical optimization by means of micro optical element (MOE) G.A. Fornaro

3. γ(511 KeV) n n e+ p p n p n n e- e+ γ(511 KeV) p p n tracer Injection (18F-FDG) p Neutron-deficient isotope Ring of scintillators LOR e+ x z Projection f f f s Reconstruction z p s Parallel projections PET data (sinograms) PET images PET Principles 2π coincidences G.A. Fornaro

4. PET: origins of noise Coincidence time window (Δt): time in which two detected photons are considered to be originated in the same event Single count rate • True coincidences • Scattered coincidences • Random coincidences Duration of scintillation In a PET detection system: Number of phe in the detector In order to reduce the noise it is important to improve the time resolution of the detecting system and thus to maximize the number of photon extracted from the crystal 12/1/2014 G.A. Fornaro

5. EndoTOFPET-US project • First clinical target: pancreatic cancers; • Develop new biomarkers; • Develop a dual modality PET-US endoscopic probe with... • Spatial resolution: 1mm • Timing resolution: 200ps FWHM coincidence • High sensitivity to detect 1mm tumors in a few minutes • Energy resolution: sufficient to discriminate against Compton events 12/1/2014 G.A. Fornaro

6. EndoTOFPET-US project Aim: build a prototype of a PET-US endoscopic probe for detection of early stage pancreatic tumors 12/1/2014 G.A. Fornaro

7. EndoTOFPET-US project Aim: build a prototype of a PET-US endoscopic probe for detection of early stage pancreatic tumors Ultrasound trasducer Scintillating crystal matrix Biopsy niddle Micro optical element d-SiPM 12/1/2014 G.A. Fornaro

8. EndoTOFPET-US project US: detects regions in which the density of the tissue changes (possible cancer) G.A. Fornaro

9. External PET Plate EndoTOFPET-US project PET detector G.A. Fornaro

10. EndoTOFPET project External PET Plate G.A. Fornaro

11. tB d Detector B d1 Patient e+ e- tA Detector A Time of Flight info reduce the statistical noise variance with G.A. Fornaro

12. tB d Detector B d1 Patient e+ e- tA Detector A Time of Flight info reduce the statistical noise variance • d-SiPM with single SPAD readout for single optical photon counting with Individual SPAD G.A. Fornaro

13. MOE: Aim and concept Problem: 50% light of the crystal is lost in the dead zones of the d-SiPM d-SiPM Crystal MOE 12/1/2014 G.A. Fornaro

14. MOE: Aim and concept Problem: 50% light of the crystal is lost in the dead zones of the d-SiPM Optical collimator/ Lenticular Lens 500µm d-SiPM Crystal MOE • Solution: optical collimator btw crystal and photodetector 12/1/2014 G.A. Fornaro

15. 25 µm 25 µm 800 µm MOE: Aim and concept Problem: 50% light of the crystal is lost in the dead zones of the d-SiPM d-SiPM Crystal MOE • Solution: optical collimator btw crystal and photodetector • Match pitches of d-SiPM (25µm active area); 12/1/2014 G.A. Fornaro

16. MOE: Aim and concept Problem: 50% light of the crystal is lost in the dead zones of the d-SiPM d-SiPM Crystal MOE d-SiPM • Solution: optical collimator btw crystal and photodetector • Match pitches of d-SiPM (50µm); • Concentrate the maximum of light into parallel rays • Create ‘differential’ light pattern on the SPAD surface only; 12/1/2014 G.A. Fornaro

17. MOE: Aim and concept Problem: 50% light of the crystal is lost in the dead zones of the d-SiPM • simulations forecast a transmission gain of 1.3 d-SiPM Crystal MOE • Solution: optical collimator between crystal and photodetector • Match pitches of d-SiPM (50µm); • Concentrate the maximum of light into parallel rays • Create ‘differential’ light pattern on the SPAD surface only; 12/1/2014 G.A. Fornaro

18. Benches for MOE characterization We have built and tested different benches for the optical characterization of the MOE: X- Rays source Matrix • Crystal + MOE in direct contact with the sensitive area of a CCD used as photodetector • Characterization of light distribution at the output of the crystal (input of MOE) • Characterization of MOE in direct contact with CCD (near field): by changing the angle of incidence of light on the MOE we detected the transmitted light at its output • Complete characterization of MOE with the camera (far field): by changing the angle of incidence of light on the MOE we detected the light distribution at its output MOE pinhole Rotating disk USB connection PMT CCD γ-Source crystal filter CCD+MOE filter θ UV Lamp γ UV Lamp MOE Digital Camera 12/1/2014 G.A. Fornaro

19. The works are in progress… Reach a convergence btw experimental parameter and the ones of simulations in order to make the comparison of the results more and more realistic Final aim: understand well the input parameters of the MOE in order to be able to forecast its output’s intensity profile Thanks for your attention! … 12/1/2014 G.A. Fornaro

20. Direct contact with CCD X- Rays source Matrix X-Rays direction Average of each vertical array of pixels CCD USB connection air interface crystal-CCD Horizontal array of averages intensities • Proteus/AGILE 4x4 crystal matrix : • all crystals fully wrapped (Vikuiti) • X-Rays (40 keV) could only penetrate and excite the first vertical row of crystal Intensity (a.u.) Bare Matrix Horizontal position (pixels) 12/1/2014 G.A. Fornaro

21. Direct contact with CCD X-Rays direction X- Rays source Matrix Average of each vertical array of pixels MOE USB connection CCD air interface crystal-MOE and MOE-CCD Horizontal array of averages intensities • Proteus/AGILE 4x4 crystal matrix : • all crystals fully wrapped (Vikuiti) • X-Rays (40 keV) could only penetrate and excite the first vertical row of crystal Intensity (a.u.) Bare Matrix Matrix + MOE (air) Horizontal position (pixels) 12/1/2014 G.A. Fornaro

22. Direct contact with CCD: matrix in dry contact with MOE Gain on single peaks For evaluating the gain we would have in the active regions of a SPAD that will be put in front of the MOE we calculated: • the integral of the intensity of light coming out from the crystal+MOE in a region of 25μm (≈5 pixels) around each peak; • the integral of the intensity of light coming out from the bare crystal in the same regions of 25 μm 3 4 12 5 6 13 14 7 8 9 10 11 25μm A.R. = gain in the active regions of a SPAD Intensity (a.u.) Bare Matrix Average gain on the peaks = 1.26 Gain forecasted by simulations =1.7 Matrix + MOE (air) Horizontal position (pixels) 12/1/2014 G.A. Fornaro

23. 4 years project WP2: CERN Crystals and optics Scintillating fibers and diffrative coupling optics WP5: DESY Detector Integration Miniaturized probe Tracking&Image fusion WP3: Delft TU Photodetectors Novel digital photodetectors WP4: LIP FE and DAQ electronics Highly integrated TOF electronics WP6: TUM Clinical requirements & preclinical and pilot clinical studies Feasibility tests on pigs, Pilot clinical tests, Impact on biomarker studies WP1: UnivMed Project Coordination G.A. Fornaro