8/18/2015G.A. Fornaro Characterization of diffractive optical elements for improving the performance of an endoscopic TOF- PET detector head Student: G. A. Fornaro Supervisor: G. Battistoni

8/18/2015G.A. Fornaro Outline  PET principles  EndoTOFPET-US: the project  Time of light (TOF) principle  Optical optimization by means of micro optical element (MOE)

8/18/2015G.A. Fornaro tracer Injection ( 18 F-FDG) Ring of scintillators PET Principles e+e+ e-e- e+e+ Neutron-deficient isotope p p p p p p n n n n p n n e+e+ γ (511 KeV) 2π coincidences Parallel projections Projection f s PET data (sinograms) s z f f PET images z x Reconstruction LOR

8/18/2015G.A. Fornaro8/18/2015 PET: origins of noise True coincidences Scattered coincidences Random coincidences Coincidence time window (Δt): time in which two detected photons are considered to be originated in the same event 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 In a PET detection system: Single count rate Duration of scintillation Number of phe in the detector

8/18/2015G.A. Fornaro8/18/2015 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

8/18/2015G.A. Fornaro8/18/2015 EndoTOFPET-US project build a prototype of a PET-US endoscopic probe for detection of early stage pancreatic tumors Aim:

8/18/2015G.A. Fornaro8/18/2015 EndoTOFPET-US project build a prototype of a PET-US endoscopic probe for detection of early stage pancreatic tumors Aim: Scintillating crystal matrix Micro optical element d-SiPM Biopsy niddle Ultrasound trasducer

8/18/2015G.A. Fornaro US: detects regions in which the density of the tissue changes (possible cancer) EndoTOFPET-US project

8/18/2015G.A. Fornaro PET detector External PET Plate EndoTOFPET-US project

8/18/2015G.A. Fornaro External PET Plate EndoTOFPET project

8/18/2015G.A. Fornaro Detector B Detector A e-e- e+e+ Patient tAtA tBtB d d1d1 Time of Flight info reduce the statistical noise variance with

8/18/2015G.A. Fornaro Detector B Detector A e-e- e+e+ Patient tAtA tBtB d d1d1 Time of Flight info reduce the statistical noise variance with d-SiPM with single SPAD readout for single optical photon counting Individual SPAD

8/18/2015G.A. Fornaro8/18/2015 Problem: 50% light of the crystal is lost in the dead zones of the d-SiPM Crystal MOE d-SiPM MOE: Aim and concept

8/18/2015G.A. Fornaro8/18/2015 Crystal Solution: optical collimator btw crystal and photodetector Optical collimator/ Lenticular Lens 500µm MOE d-SiPM Problem: 50% light of the crystal is lost in the dead zones of the d-SiPM MOE: Aim and concept

8/18/2015G.A. Fornaro8/18/2015 1)Match pitches of d-SiPM (25µm active area); 800 µm 25 µm Crystal Solution: optical collimator btw crystal and photodetector MOE d-SiPM Problem: 50% light of the crystal is lost in the dead zones of the d-SiPM MOE: Aim and concept

8/18/2015G.A. Fornaro8/18/2015 1)Match pitches of d-SiPM (50µm); 2)Concentrate the maximum of light into parallel rays 3)Create ‘differential’ light pattern on the SPAD surface only; Solution: optical collimator btw crystal and photodetector MOE Crystal d-SiPM Problem: 50% light of the crystal is lost in the dead zones of the d-SiPM MOE: Aim and concept

8/18/2015G.A. Fornaro Problem: 50% light of the crystal is lost in the dead zones of the d-SiPM 1)Match pitches of d-SiPM (50µm); 2)Concentrate the maximum of light into parallel rays 3)Create ‘differential’ light pattern on the SPAD surface only; Solution: optical collimator between crystal and photodetector 8/18/2015 simulations forecast a transmission gain of 1.3 simulations forecast a transmission gain of 1.3 MOE: Aim and concept

8/18/2015G.A. Fornaro8/18/2015 We have built and tested different benches for the optical characterization of the MOE:  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 X- Rays source Matrix CCD USB connection MOE CCD+MOE Rotating disk filter pinhole PMT γ-Source crystal UV Lamp MOE θ γ filter UV Lamp Digital Camera Benches for MOE characterization

8/18/2015G.A. Fornaro8/18/2015 … Thanks for your attention! 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

8/18/2015G.A. Fornaro8/18/2015 Direct contact with CCD X- Rays source Matrix CCD USB connection 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 Horizontal position (pixels) Intensity (a.u.) X-Rays direction Bare Matrix air interface crystal-CCD Average of each vertical array of pixels Horizontal array of averages intensities

8/18/2015G.A. Fornaro Horizontal position (pixels) Intensity (a.u.) Bare Matrix Matrix + MOE (air) 8/18/2015 Direct contact with CCD X-Rays direction air interface crystal-MOE and MOE-CCD X- Rays source Matrix CCD USB connecti on MOE 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 Average of each vertical array of pixels Horizontal array of averages intensities

8/18/2015G.A. Fornaro Intensity (a.u.) Bare Matrix Matrix + MOE (air) 25μm Horizontal position (pixels) 8/18/2015 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: 1.the integral of the intensity of light coming out from the crystal+MOE in a region of 25μm (≈5 pixels) around each peak; 2.the integral of the intensity of light coming out from the bare crystal in the same regions of 25 μm A.R. = gain in the active regions of a SPAD peak A.R Average gain on the peaks = 1.26 Gain forecasted by simulations =1.7 Direct contact with CCD: matrix in dry contact with MOE Gain on single peaks

8/18/2015G.A. Fornaro WP1: UnivMed Project Coordination WP2: CERN Crystals and optics Scintillating fibers and diffrative coupling optics WP6: TUM Clinical requirements & preclinical and pilot clinical studies Feasibility tests on pigs, Pilot clinical tests, Impact on biomarker studies WP3: Delft TU Photodetectors Novel digital photodetectors WP4: LIP FE and DAQ electronics Highly integrated TOF electronics WP5: DESY Detector Integration Miniaturized probe Tracking&Image fusion 4 years project