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Radiation in Medical Imaging

Inorganic Scintillators in Medical-imaging Detectors C.W.E. van Eijk A msterdam, 9 September 2002. transmission. emission. Efficiency Inorganic scintillator. Radiation in Medical Imaging. Modality. Energies

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Radiation in Medical Imaging

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  1. Inorganic ScintillatorsinMedical-imaging DetectorsC.W.E. van Eijk Amsterdam, 9 September 2002

  2. transmission emission Efficiency Inorganic scintillator Radiation in Medical Imaging Modality Energies X-ray imaging Mammography 25 kVp, ~18 keV Radiography, chest 150 kVp Fluoroscopy 150 kVp X-ray CT 150 kVp Nuclear medicine Scintigraphy 80 - 140 keV SPECT 60 - 511 keV PET 511 keV

  3. Interventional Radiology Fluoroscopy - Real time - Low dose ImageIntensifier Mobile C-arm system for full surgical and minimally-invasive procedures From: Philips Medical Systems BV300 series

  4. Interventional Radiology minimally-invasive procedure Transjugular Intrahepatic Portosystemic Shunt (TIPS)

  5. Columnar CsI:Tl ADC addressing readout Interventional Radiology Flat panel detector - Amorphous silicon 2k x 2k 40 x 40 cm2 also for radiography Flat X-ray Detectors for Medical Imaging Dr. Michael Overdick Session 5 From: Philips, Aachen

  6. Interventional Radiology Flat panel detector - Amorphous silicon Photodiode signal depends on: • scintillator light yield • optical coupling • spectral matching • diode efficiency From: Philips, Aachen

  7. Interventional Radiology CsI:Tl pillar growth induced by evaporation technique • crack structure • focussing of light • >500 µm layers • high MTF From: Philips, Aachen

  8. ~ 16 x 1 mm 1-D or 2-D position-sensitive detector (rotating) ~ 1 k x 1 mm X-ray fan beam (rotating) + Ceramic scintillators + photodiodes + X-ray source (rotating) X-ray Computed Tomography E. Hell et al, NIM A 454 (2000) 40-48

  9. X-ray Computed Tomography 1974: 80 x 80 pixels slices of 13 mm spacing 2000: 1024 x 1024 pixels spiral scanning From: W.A. Kalender, CT, 2000, MCD Verlag

  10. X-ray Computed Tomography Ceramic Scintillators 4 density ρZ light yield dec. time afterglow wavel. max. (g/cm3) (106) (phot./MeV) (μs) (% after (nm) 3/100 ms) CdWO4 134 20,000 7.9 5 < 0.1/ 495 0.02 Bi4Ge3O12 (BGO) 7.1 227 9,000 0.3 480 > 6 >2/0.3 550 CsI:Tl 4.5 38 66,000 8 - Gd2O2S:Pr,Ce,F 7.3 103 35,000 4 < 0.1/< 0.01 510 Gd2O2S:Pr (UFC) 7.3 103 50,000 3 0.02/0.002 510 Y1.34 Gd0.60 O3:(Eu,Pr)0.06 5.9 44 44,000 1000 4.9/< 0.01 610 (Hilight) Gd3Ga5O12:Cr,Ce < 0.1/0.01 730 7.1 58 40,000 140 Lu2O3:Eu,Tb 9.4 211 30,000 > 1000 > 1/0.3 610

  11. X-ray Computed Tomography Afterglow in scintillators 1 angle per < ms From: W.A. Kalendber, CT, 2000, MCD Verlag

  12. Collinearly emitted 511 keV quanta detected in coincidence Detectors BGO + PMT Radiopharmaceutical β+ emitter Bi4Ge3O12 Positron Emission Tomography Detector ring (inner diam. ~ 0.8 m)

  13. Positron Emission Tomography PET systemsSiemens-CTI http://www.epub.org.br/cm/n01/pet/pet_hist.htm

  14. BGO detector block 8 x 8 columns of 6 x 6 x 30 mm3 A B 4 PMTs C D 30 mm Bi4Ge3O12 PET Detector Block Efficiency

  15. Septa removed Septa 2D 3D Positron Emission Tomography: 2D & 3D

  16. Positron Emission Tomography 3D PET Increase Random coincidences ~N2singlesτ Time resolution Energy resolution Light yield Decay time Non-proportionality From: G. Muehllehner et al. & SCINT 2001

  17. Positron Emission Tomography PET Scintillators  1/μ511 keV light yield  (g/cm3) (mm) /PE (%) (photons/MeV) (ns) (nm) Bi4Ge3O12(BGO)7.1 11.6 / 44 9,000 300 480 Lu2SiO5:Ce (LSO) 7.4 12.3 / 34 26,000 40 420 Gd2SiO5:Ce (GSO) 6.7 15 / 26 8,000 60 440 LuxY1-xAlO3:Ce(LuAP) 8.3 11.0 / 32 11,000 18 365 Lu2Si2O7:Ce (LPS) 6.2 14.5 / 29 20,000 30 380 Energy resolution poor

  18. LaCl :Ce LaCl :Ce 1600 3 3 1400 1200 1000 COUNTS COUNTS counts 800 600 400 200 0 600 700 E (keV) energy [keV] E (keV) Scintillators Energy Resolution LaCl3:Ce(10%) ΔE/E = 3.1 % photomultiplier readout Hamamatsu R1791 E.V.D. van Loef et al Appl. Phys. Lett. 77 (2000) 1467

  19. Off centre: parallax erroror radial elongation incorrect Line of Response PET basics: Position resolution Efficient High position resolution Remedy: Depth of Interaction measurement DOI

  20. PET: Depth of Interaction in HRRT PMTs Light guides LSO scintillators Lu2SiO5:Ce 7.5 x 2.1 x 2.1 mm3 Different decay times in the two layers  Different pulse shape  DOI PMTs From: D.W. Townsend, C. Morel presented at SCINT 2001 K. Wienhard et al 2000 IEEE NSS/MIC CDROM 17 280

  21. PET: DOI Crystal Clear Depth of Interaction LSO LuAP APD array Pulse shape discrimination Saoudi et al IEEE Trans Nucl Sci 46(1999)462, also 479 Seidel et al IEEE Trans Nucl Sci 46(1999)485

  22. Positron Emission Tomography Multi modality PET + MRI Blood flow changes under speech activation (red) Tumor (green) From: Klaus Wienhard MPI für Neurologische Forschung, Köln

  23. Inorganic Scintillators in Medical-imaging Detectors Conclusion Interest in further improvement of inorganic scintillators Fundamental research Especially for PET also Mammography PET Small Animal PET Use of new light detectors APDs Silicon drift detectors C.W.E. van Eijk Inorganic scintillators in medical imaging Phys.Med.Biol. 47 (2002) R85 - R106

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