1 / 34

Development of a novel photodetector readout technique for PET and CT

Development of a novel photodetector readout technique for PET and CT. Introduction to PET. Injection of a radiotracer (FDG) ~ radioactive glucose (30min). 511 keV. 511 keV. Injection d’un radiotraceur émetteur +. Introduction to PET. Photodetector. Time precision. Introduction to PET.

grover
Download Presentation

Development of a novel photodetector readout technique for PET and CT

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Development of a novel photodetector readout technique for PET and CT F. POWOLNY 07 / 12 / 2007

  2. Introduction to PET Injection of a radiotracer (FDG) ~ radioactive glucose (30min) 511 keV 511 keV F. POWOLNY 07 / 12 / 2007

  3. Injection d’un radiotraceur émetteur + Introduction to PET Photodetector Time precision F. POWOLNY 07 / 12 / 2007

  4. Introduction to PET F. POWOLNY 07 / 12 / 2007

  5. Introduction to CT X-ray source detector F. POWOLNY 07 / 12 / 2007

  6. PET / CT image fusion CT PET metabolic anatomical PET / CT F. POWOLNY 07 / 12 / 2007

  7. Development of a novel photodetector readout technique for PET and CT F. POWOLNY 07 / 12 / 2007

  8. Motivation • Use CERN technology for bio-medical applications • BioCare FP6 european project • Show its suitability to PET–CT detection • 511 keV gammas for PET • 122 keV X-rays for CT at 200 Mcounts cm-2s-1 • Time-based approach to read out LSO crystals and APD array • fast, precise, cost effective, lower power consumption, reliable F. POWOLNY 07 / 12 / 2007

  9. System description • LSO + APD array • Front End electronics Energy Resolution Timing precision Interpretation of results F. POWOLNY 07 / 12 / 2007

  10. Outline System description • LSO + APD array • Front End electronics Energy Resolution Timing precision Interpretation of results F. POWOLNY 07 / 12 / 2007

  11. NINO FEDC05 APD Array Presentation of the system LSO 25 ps time jitter F. POWOLNY 07 / 12 / 2007

  12. How the system works Current pulse g511keV voltage pulse 420nm LSO crystals APD FEDC05 3000 photons ~60 fC 20 mV / fC ~1.20 V Current pulse 4 kW TDC NINO ~ 300 mA F. POWOLNY 07 / 12 / 2007

  13. Commercial Apparatus • LSO crystal • Chosen for many PET applications • Light yield ~ 20 000 photons / MeV for 2 x 2 x 10 mm3 crystals vertical position • Emission at 420 nm • Fast : 40 ns time constant • APD array • 32 channels of 2 x 2 mm2 • Selected gain of 175 +/- 10 (bias 390V) F. POWOLNY 07 / 12 / 2007

  14. APD P+ E E Absorption I P Multiplication N+ HV F. POWOLNY 07 / 12 / 2007

  15. CERN front end • FEDC 05 chip • Preamplifier developed for Atlas silicon trackers (LHC) • 1000 electrons noise • Gain = 20 mV / fC ~ 1 V / 105 electrons • 16 channels • 22 ns peaking time • NINO chip • developed for Alice TOF (LHC) • Ultra-fast low-power discriminator. • 8 channels • 1 ns peaking time • 25 ps rms time jitter • Time over threshold technique F. POWOLNY 07 / 12 / 2007

  16. NINO functioning: Time over threshold Input of Nino t Nino threshold I (t) Time walk V (t) Time walk a pulse width t Output of Nino F. POWOLNY 07 / 12 / 2007

  17. {FEDC 05 + NINO} Simulations Input charges from 105 to 106 electrons FEDC 05 NINO Pulse Width Time Walk F. POWOLNY 07 / 12 / 2007

  18. FEDC 05 + NINO calibration 122 keV CT mode 511 keV PET mode F. POWOLNY 07 / 12 / 2007

  19. outline • System description • LSO + APD array • Front End electronics Energy Resolution Timing precision Interpretation of results F. POWOLNY 07 / 12 / 2007

  20. PET performance : 22Na measurements 511 keV ? 1275 keV ? F. POWOLNY 07 / 12 / 2007

  21. Spectra interpretation • Photoelectric effect : the total photon energy is absorbed in the crystal • Compton scattering : elastic choc photon / electron E’ absorbed E’ = E0 - E1 E’(q) F. POWOLNY 07 / 12 / 2007

  22. FWHM F. POWOLNY 07 / 12 / 2007

  23. PET performance : 22Na measurements backscatter 1275 keV 511 keV Look up table F. POWOLNY 07 / 12 / 2007

  24. Energy Resolution :PMT / APD comparison LSO 2 x 2 x 10 mm3 122keV 511keV 662keV 1275keV F. POWOLNY 07 / 12 / 2007

  25. Outline • System description • LSO + APD array • Front End electronics Energy Resolution Timing precision Interpretation of results F. POWOLNY 07 / 12 / 2007

  26. Time Coincidence measurement APD / APD APD APD 22Na NINO FEDC 05 FEDC 05 NINO Discri Gate: width ~ 170 ns scope F. POWOLNY 07 / 12 / 2007

  27. Simulation of NINO Time walk vs. Pulse width Time walk ~ 14 ns F. POWOLNY 07 / 12 / 2007

  28. Data correction Global Time coincidence After Photopeak selection No of Counts After Photopeak selection and Time Walk correction Time Coincidence [ns] F. POWOLNY 07 / 12 / 2007

  29. Gaussian Fit FWHM = 1.6 ns After Photopeak selection and Time Walk correction F. POWOLNY 07 / 12 / 2007

  30. System description • LSO + APD array • Front End electronics Energy Resolution Timing precision Interpretation of results F. POWOLNY 07 / 12 / 2007

  31. Jitter composition F. POWOLNY 07 / 12 / 2007

  32. Conclusions • The prototype is suitable to detect photons in the PET and CT range • The energy resolution is comparable to PMTs at 511 keV • The Coincidence time resolution is 1.6 ns FWHM • Electronics are no longer the limiting factor F. POWOLNY 07 / 12 / 2007

  33. Perspectives and improvements • Change the photosensor to improve the time resolution • SiPM • a-Si:H MCP F. POWOLNY 07 / 12 / 2007

  34. Questions? F. POWOLNY 07 / 12 / 2007

More Related