Inorganic Scintillators in Medicalimaging Detectors C W E

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

Radiation in Medical Imaging X-ray imaging transmission Nuclear medicine emission Efficiency TU Delft Modality Energies Mammography 25 k. Vp, ~18 ke. V Radiography, chest 150 k. Vp Fluoroscopy 150 k. Vp X-ray CT 150 k. Vp Scintigraphy 80 - 140 ke. V SPECT 60 - 511 ke. V PET 511 ke. V Inorganic scintillator IRI-ST

Interventional Radiology Fluoroscopy - Real time - Low dose Image. Intensifier From: Philips Medical Systems BV 300 series Mobile C-arm system for full surgical and minimally-invasive procedures TU Delft IRI-ST

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

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

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

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

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

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 TU Delft IRI-ST

X-ray Computed Tomography Ceramic Scintillators density (g/cm 3) ρZ 4 light yield (106) (phot. /Me. V) dec. time (μs) afterglow wavel. max. (% after (nm) 3/100 ms) Cd. WO 4 Bi 4 Ge 3 O 12 (BGO) Cs. I: Tl 7. 9 7. 1 4. 5 134 227 38 20, 000 9, 000 66, 000 5 0. 3 8 - > 6 < 0. 1/ 0. 02 >2/0. 3 495 480 550 Gd 2 O 2 S: Pr, Ce, F 7. 3 Gd 2 O 2 S: Pr (UFC) 7. 3 Y 1. 34 Gd 0. 60 O 3: (Eu, Pr)0. 06 5. 9 103 44 35, 000 50, 000 44, 000 4 3 1000 < 0. 1/< 0. 01 0. 02/0. 002 4. 9/< 0. 01 510 610 Gd 3 Ga 5 O 12: Cr, Ce Lu 2 O 3: Eu, Tb 58 211 40, 000 30, 000 140 > 1000 < 0. 1/0. 01 > 1/0. 3 730 610 (Hilight) TU Delft 7. 1 9. 4 IRI-ST

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

Positron Emission Tomography Detector ring (inner diam. ~ 0. 8 m) Detectors BGO + PMT Bi 4 Ge 3 O 12 TU Delft Collinearly emitted 511 ke. V quanta detected in coincidence Radiopharmaceutical β+ emitter IRI-ST

Positron Emission Tomography PET systems Siemens-CTI TU Delft http: //www. epub. org. br/cm/n 01/pet_hist. htm IRI-ST

PET Detector Block BGO detector block 8 x 8 columns of 6 x 30 mm 3 A C 30 mm B 4 PMTs D Efficiency Bi 4 Ge 3 O 12 TU Delft IRI-ST

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

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

Positron Emission Tomography PET Scintillators 1/μ 511 ke. V light yield (g/cm 3) (mm) /PE (%) (photons/Me. V) Bi 4 Ge 3 O 12 (BGO) Lu 2 Si. O 5: Ce (LSO) Gd 2 Si. O 5: Ce (GSO) Lux. Y 1 -x. Al. O 3: Ce (Lu. AP) Lu 2 Si 2 O 7: Ce (LPS) 7. 1 7. 4 6. 7 8. 3 6. 2 11. 6 / 44 12. 3 / 34 15 / 26 11. 0 / 32 14. 5 / 29 9, 000 26, 000 8, 000 11, 000 20, 000 (ns) (nm) 300 40 60 18 30 480 420 440 365 380 Energy resolution poor TU Delft IRI-ST

Scintillators Energy Resolution La. Cl 3: Ce(10%) ΔE/E = 3. 1 % La. Cl 3 : Ce 1600 1400 COUNTS counts COUNTS 1200 1000 800 600 400 200 0 600 700 energy E [ke. V] (ke. V) E (ke. V) photomultiplier readout Hamamatsu R 1791 TU Delft E. V. D. van Loef et al Appl. Phys. Lett. 77 (2000) 1467 IRI-ST

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

PET: Depth of Interaction in HRRT PMTs Light guides LSO scintillators Lu 2 Si. O 5: Ce 7. 5 x 2. 1 mm 3 Different decay times in the two layers Different pulse shape DOI TU Delft From: D. W. Townsend, C. Morel presented at SCINT 2001 K. Wienhard et al 2000 IEEE NSS/MIC CDROM 17 280 PMTs IRI-ST

PET: DOI Crystal Clear Depth of Interaction LSO Lu. AP APD array Pulse shape discrimination TU Delft Saoudi et al IEEE Trans Nucl Sci 46(1999)462, also 479 Seidel et al IEEE Trans Nucl Sci 46(1999)485 IRI-ST

Positron Emission Tomography Multi modality PET + MRI Blood flow changes under speech activation (red) Tumor (green) From: Klaus Wienhard MPI für Neurologische Forschung, Köln 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 TU Delft C. W. E. van Eijk Inorganic scintillators in medical imaging Phys. Med. Biol. 47 (2002) R 85 - R 106 IRI-ST