Inorganic Scintillators in Medical-imaging Detectors C. W. E Inorganic Scintillators in Medical-imaging Detectors C.W.E. van Eijk Amsterdam, 9 September 2002

Efficiency Inorganic scintillator Radiation in Medical Imaging 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 Modality emission transmission Efficiency Inorganic scintillator

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

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

Flat panel detector - Amorphous silicon Interventional Radiology Flat panel detector - Amorphous silicon Columnar CsI:Tl ADC readout addressing 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

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

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

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

From: W.A. Kalender, CT, 2000, MCD Verlag 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

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 7.9 134 20,000 5 < 0.1/ 0.02 495 Bi4Ge3O12 (BGO) 7.1 227 9,000 0.3 480 CsI:Tl 4.5 38 66,000 8 > 6 >2/0.3 550 - 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 7.1 58 40,000 140 < 0.1/0.01 730 Lu2O3:Eu,Tb 9.4 211 30,000 > 1000 > 1/0.3 610

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

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

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

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

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

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

Positron Emission Tomography PET Scintillators  1/μ 511 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

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

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

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

Pulse shape discrimination 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

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

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