TU Delft IRI-ST Inorganic Scintillators in Medical-imaging Detectors C.W.E. van Eijk A msterdam, 9 September 2002

TU Delft IRI-ST 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 keV SPECT keV PET 511 keV Efficiency Inorganic scintillator Modality emission transmission

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

TU Delft IRI-ST Transjugular Intrahepatic Portosystemic Shunt (TIPS) Interventional Radiology minimally-invasive procedure

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

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

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

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

TU Delft IRI-ST 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

TU Delft IRI-ST density ρZ 4 light yield dec. time afterglow wavel. max. (g/cm 3 ) (10 6 ) (phot./MeV) (μs) (% after (nm) 3/100 ms) CdWO ,000 5 < 0.1/ Bi 4 Ge 3 O 12 (BGO) , CsI:Tl , > 6 >2/ Gd 2 O 2 S:Pr,Ce,F ,000 4 < 0.1/< Gd 2 O 2 S:Pr (UFC) , / Y 1.34 Gd 0.60 O 3 :(Eu,Pr) , /< (Hilight) Gd 3 Ga 5 O 12 :Cr,Ce , < 0.1/ Lu 2 O 3 :Eu,Tb ,000 > 1000 > 1/ X-ray Computed Tomography Ceramic Scintillators

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

TU Delft IRI-ST Positron Emission Tomography Detector ring (inner diam. ~ 0.8 m) Collinearly emitted 511 keV quanta detected in coincidence Radiopharmaceutical β + emitter Detectors BGO + PMT Bi 4 Ge 3 O 1 2

TU Delft IRI-ST PET systems Siemens-CTI Positron Emission Tomography

TU Delft IRI-ST PET Detector Block A B C D 4 PMTs BGO detector block 8 x 8 columns 30 mm of 6 x 6 x 30 mm 3 Bi 4 Ge 3 O 1 2 Efficiency

TU Delft IRI-ST Positron Emission Tomography: 2D & 3D

TU Delft IRI-ST From: G. Muehllehner et al. & SCINT 2001 Increase Random coincidences ~ N 2 singles τ 3D PET Energy resolution Time resolution Positron Emission Tomography Light yield Decay time Non-proportionality

TU Delft IRI-ST Bi 4 Ge 3 O 12 (BGO) / 44 9, Lu 2 SiO 5 :Ce (LSO) / 34 26, Gd 2 SiO 5 :Ce (GSO) / 26 8, Lu x Y 1-x AlO 3 : Ce (LuAP) / 32 11, Lu 2 Si 2 O 7 :Ce (LPS) / 29 20,  1 /μ 511 keV light yield  (g/cm 3 ) (mm) /PE (%) (photons/MeV) (ns) (nm) Positron Emission Tomography PET Scintillators Energy resolution poor

TU Delft IRI-ST ΔE/E = 3.1 % photomultiplier readout Hamamatsu R1791 LaCl 3 :Ce(10%) Scintillators Energy Resolution LaCl 3 :Ce counts energy [keV] LaCl 3 :Ce E (keV) COUNTS E.V.D. van Loef et al Appl. Phys. Lett. 77 (2000) 1467

TU Delft IRI-ST 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

TU Delft IRI-ST PET: Depth of Interaction in HRRT PMTs LSO scintillators Light guides PMTs 7.5 x 2.1 x 2.1 mm 3 From: D.W. Townsend, C. Morel presented at SCINT 2001 K. Wienhard et al 2000 IEEE NSS/MIC CDROM Lu 2 SiO 5 :Ce Different decay times in the two layers  Different pulse shape  DOI

TU Delft IRI-ST Depth of Interaction 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 LSO PET: DOI Crystal Clear

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

TU Delft IRI-ST 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