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Lutetium Yttrium Orthosilicate Single Crystal Scintillator Detector

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Lutetium Yttrium Orthosilicate Single Crystal Scintillator Detector University of Central Florida STARS UCF Patents Technology Transfer 7-26-2005 Lutetium Yttrium Orthosilicate Single Crystal Scintillator Detector Bruce Chai Yangyang Ji Crystal Photonics, Inc. Find similar works at: https://stars.library.ucf.edu/patents University of Central Florida Libraries http://library.ucf.edu This Patent is brought to you for free and open access by the Technology Transfer at STARS. It has been accepted for inclusion in UCF Patents by an authorized administrator of STARS. For more information, please contact [email protected]. Recommended Citation Chai, Bruce and Ji, Yangyang, "Lutetium Yttrium Orthosilicate Single Crystal Scintillator Detector" (2005). UCF Patents. 737. https://stars.library.ucf.edu/patents/737 Illlll llllllll Ill lllll lllll lllll lllll lllll 111111111111111111111111111111111 US006921901Bl (12) United States Patent (10) Patent No.: US 6,921,901 Bl Chai et al. (45) Date of Patent: *Jul. 26, 2005 (54) LUTETIUM YTTRIUM ORTHOSILICATE GB 1336518 * 11/1973 SINGLE CRYSTAL SCINTILLATOR DETECTOR OTHER PUBLICATIONS (75) Inventors: Bruce H. T. Chai, Oviedo, FL (US); IEEE Transactions on Nuclear Science, vol. 36, No. 1, Feb. Yangyang Ji, Orlando, FL (US) 1989, Ishibashi, et al. "Cerium Doped GSO Scintillators and its Application to Position Sensitive Detectors" pp. (73) Assignees: Crystal Photonics, Inc., Sanford, FL 170-172.* (US); Research Foundation of the IEEE Transactions on Nuclear Science, vol. 40, No. 4, Aug. University of Central Florida, 1993, Daghighian, et al. "Evaluation of Cerium Doped Orlando, FL (US) Lutetium Oxyorthosilicate (LSO) Scintillation Crystal for PET" 1045-1047.* ( *) Notice: Subject to any disclaimer, the term of this IEEE Transactions on Nuclear Science, vol. 43, No. 3, Jun. patent is extended or adjusted under 35 1996, Novotny, et al. "A Plastic-BaF2 Phoswich Telescope U.S.C. 154(b) by 0 days. for Charged/Neutral Particle and Photon Detection" pp 1260-1266. * This patent is subject to a terminal dis­ Melcher et al. Czochralski growth of rare earth oxyortho­ claimer. silicate single crystals. J. of Crystal Growth, vol. 128 (1993), pp. 1001-1005.* (21) Appl. No.: 10/623,226 Loutts et al. Czochralski growth and caharcterization of (22) Filed: Jul. 18, 2003 (Lul-xGdx)2Si05 single crystals for scintillators. J. of Crystal Growth, vol. 174 (1997), pp. 331-336.* Related U.S. Application Data Primary Examiner---Constantine Hannaher (62) Division of application No. 09/506,160, filed on Feb. 17, Assistant Examiner-Shun Lee 2000, now Pat. No. 6,624,420. (74) Attorney, Agent, or Firm-Brian S. Steinberger; Law ( 60) Provisional application No. 60/120,500, filed on Feb. 18, Offices of Brian S. Steinberger, P.A. 1999. (51) Int. Cl.7 .......................... GOlT 1/202; C09K 11/08 (57) ABSTRACT (52) U.S. Cl. ............................. 250/361 R; 252/301.4 F A single crystal having the general composition, Ce2x(Lu 1 _Y (58) Field of Search ................ 250/361 R; 252/301.4 F Yy)2 ci-x)Si05 where x=approximately 0.00001 to approxi­ mately 0.05 and y=approximately 0.0001 to approximately (56) References Cited 0.9999; preferably where x ranges from approximately U.S. PATENT DOCUMENTS 0.0001 to approximately 0.001 and y ranges from approxi­ mately 0.3 to approximately 0.8. The crystal is useful as a 4,549,083 A * 10/1985 Ozawa .................... 250/458.1 scintillation detector responsive to gamma ray or similar 4,664,744 A * 5/1987 Le Gal et al. .................. 117/3 high energy radiation. The crystal as scintillation detector 4,928,017 A * 5/1990 Kemmler-Sack et al. 250/483.1 has wide application for the use in the fields of physics, 4,958,080 A * 9/1990 Melcher .................. 250/483.1 chemistry, medicine, geology and cosmology because of its (Continued) enhanced scintillation response to gamma rays, x-rays, cos­ mic rays and similar high energy particle radiation. FOREIGN PATENT DOCUMENTS DE 2234968 * 1/1973 14 Claims, 5 Drawing Sheets SCINTILLATING DETECTORS - Ce 3+:LYSO PHOTOMULTIPLIER ._ CRYSTAL OR OTHER PHOTO-DETECTOR US 6,921,901 Bl Page 2 U.S. PATENT DOCUMENTS 5,660,627 A * 8/1997 Manente et al. .............. 117/12 5,690,731 A * 11/1997 Kurata et al. ................. 117/13 5,003,181 A * 3/1991 Morlotti .................. 250/484.4 5,729,584 A * 3/1998 Moorman et al. .......... 378/146 5,025,151 A * 6/1991 Melcher .................. 250/269.6 5,751,785 A * 5/1998 Moorman et al. .......... 378/146 5,164,041 A * 11/1992 Berkstresser et al. ......... 117/19 5,835,561 A * 11/1998 Moorman et al. ............ 378/98 5,500,147 A * 3/1996 Fitzpatrick ............ 252/301.6 S 5,859,893 A * 1/1999 Moorman et al. .......... 378/154 5,610,967 A * 3/1997 Moorman et al. .......... 378/154 6,323,489 Bl * 11/2001 McClellan .............. 250/361 R 5,644,612 A * 7/1997 Moorman et al. ......... 378/98.2 5,651,047 A * 7/1997 Moorman et al. ......... 378/98.8 * cited by examiner U.S. Patent Jul. 26, 2005 Sheet 1 of 5 US 6,921,901 Bl (i'll:R) 81.0l) NOll:J3S SS01KJ NOISSIWtl M oo 0 "° """ V") 0 V'l ~ ~ 0 ..-... s~ ~ ~u ]'O....., r.n o~ §~ 00~ 0 in ~ ~< ~~ ~ ""'"4 l/')""""4 0 {/.) ~ . • ,-I rJ'.) 0 0 ~~ 00~ M ~ ~\il.. 0 I.I) M+ N u(l) 0 0 ll') -q- M M - ON _0I) NOIJ..::>3S SSOD NOI.L«IBOSHV <zw:> 81 U.S. Patent Jul. 26, 2005 Sheet 2 of 5 US 6,921,901 Bl ('lmo _oI) NOI.l.J3:S SSOHJ NOISSIW3 81 IQ "l:t" N Oo c Ir) 0 ~ ...,.Ir) ~ ~~ 0 - ,-..... ~u ~ 0 i:.tJ !~ 00~ ~~ 0 0 Ir) ~~.,..,g ~ ~~ 0 (/) •...C (/) ~d :=:: ~ ~ 8 ~ ~~ ('f"I ~~ .. 0 11"1 + N M uQ) 0 ...,. 0 -0 00 '° N ON <zmos1-0l) NOLI.::>HS SSOD NOllcilIOSHV d • \JJ. • ~ ......~ SCINTILLATING DETECTORS ~ =...... ~ ~ N O'I ~ cN c Ul Ce 3+:LYSO PHOTOMULTIPLIER 'Jl ~=­ CRYSTAL OR OTHER PHOTO-DETECTOR ~ ~ 0....., Ul e rJ'J. O'I \o N lo-" \o Q FIG. 2 lo-" ~ lo-" U.S. Patent Jul. 26, 2005 Sheet 4 of 5 US 6,921,901 Bl 8 .-4 N - I ' I 0 ~~ oc I VJ~ ~ r H o. I ~ ...:IM \ ~ . ~E-4 J 0 / 3 1-4 < ~~ ( 0 ~ \ '#. ~ ~',, c u N en . ............. --.. ) \ • 0 0 0 0 0 0 0 c 0 0 -8 0\ co I:"-- \0 ~ "'='" ~ "N - (U) fBN OJ. HALL V'Itnl (%) O'I3L\ J.HDI'I •d \JJ. • ~ EFFECTIVE Z AS A FUNCTION OF Lu ......~ ~ INLYSO =...... 70 65 ~ :- N 60 ~~ cN c N 55 Ul u~ so 'Jl ~=­ ~ .....~ i:a 45 Ul 0....., 40 Ul 35 30 e 0 20 40 60 80 100 rJ'J. -..a-.. \0 % OF Lu IN L YSO N J-' \0 Q FIG. 4 lo-" ~ lo-" US 6,921,901 Bl 1 2 LUTETIUM YTTRIUM ORTHOSILICATE EGO was found in the early 70's. It has higher density 3 SINGLE CRYSTAL SCINTILLATOR (7.13 g/cm ), and is non-hygroscopic. But it also has prob­ DETECTOR lems such as low light yield (15% that of NaI(Tl)), slow decay time (300 ns) and high refractive indices (n=2.15) This is a Divisional of application Ser. No. 09/506,160 5 which results in light loss due to internal reflection. Still filed Feb. 17, 2000, now U.S. Pat. No. 6,624,420. This EGO scintillator crystals are now used in high energy invention relates to a single crystal as scintillating detector calorimetry in particle physics research Institutes. It is also for gamma ray or similar high energy radiation which single used as the detector for the 511 ke V gamma-ray radiation of the positron emission tomographs (PE1) in medical imaging crystal is composed of Cerium doped Lutetium Yttrium application. Because of the low light and slow decay, the orthosilicate (LYSO) with the general composition of Ce2x 10 image produced from the EGO PET machine tends to be (Lu _Y Yy) ci-x)Si0 where x=0.0001 to 0.02 and y=0.0001 to 1 2 5 blurred with poor resolution. 1.9999 and claims priority based on U.S. Provisional Appli­ In early 80's, the Ce doped GSO crystal was disclosed as cation Ser. No. 60/120,500 filed Feb. 18, 1999. 3 a scintillator material. It has adequate density ( 6.71 g/cm ) BACKGROUND AND PRIOR ART 15 and is also non-hydrogroscopic. The light yield is 20% of There are a number of ways to detect high energy radia­ that obtained with N aI(Tl) with a much faster decay time ( 60 tion. Some of the equipment can be quite bulky, such as a ns). Even though GSO crystals over 80 mm diameter have cloud chamber, others may not be as sensitive or quantita­ been produced, the crystal has not yet made it in the PET tive. Scintillator is a very simple but also very accurate market because of a strong cleavage plane. It is very difficult method to detect high energy radiation such as x-rays, 20 to cut and polish the crystal into any specific shape without gamma-rays, high energy particles exceeding a few kilo­ the risk of fracturing of the entire crystal. Another unex­ electron-volts (Ke V) in energy. When high energy radiation pected problem is the high thermal neutron capture cross­ strikes on a scintillating crystal, it creates a large number of section (49,000 barns) of the gadolinium. It will interfere electron-hole pairs inside the crystal. Recombination of with the gamma rays generated by neutron irradiation these electron-hole pairs will release energy in the range of 25 source. However, since there is no neutron source involved a few e V.
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