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Park C, Kim S, Melis A, Seo J, Cho S, Yeom JY. Time-resolved photoluminescence analysis of ceramic Ce:GAGG scintillators. OPTICS EXPRESS 2023; 31:34677-34687. [PMID: 37859218 DOI: 10.1364/oe.498651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 08/29/2023] [Indexed: 10/21/2023]
Abstract
This paper introduces the characteristics and efficiency of post-treatment methods for enhancing the timing resolution of ceramic Ce:GAGG scintillators. The thermal annealing and surface treatments were included to analyze their impact on time-resolved photoluminescence (TRPL) and thermoluminescence (TL) characteristics. Optical properties were improved by suppressing nonradiative recombination due to the reduced surface defects, while heat-treatment removes traps as confirmed by TL measurements. TRPL decay characteristics revealed that samples treated with mechanical polishing followed by heat treatment exhibited the best scintillation performance, with a slow component of 272.3 ns. These findings will aid in developing techniques for improving the luminescence of other inorganic scintillators.
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Kolcu OB, Iren E, Yetkin T, Özok F, Erduran MN. Measurement of LYSO crystal light output and energy resolution improvement with acid etching. Appl Radiat Isot 2023; 199:110902. [PMID: 37379787 DOI: 10.1016/j.apradiso.2023.110902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 05/27/2023] [Accepted: 06/14/2023] [Indexed: 06/30/2023]
Abstract
In this study, we investigated the impact of chemical etching on the light output and energy resolution of LYSO scintillators using simple, affordable laboratory equipment. We found that etching with phosphoric acid at temperatures between 180 °C and 190 °C improved the light output and energy resolution compared to mechanically polished crystals, even after minimal etching times. Our results show that with 7.5 min of chemical etching, the light output increase rate is 45.7%, and the relative energy resolution improvement is 12%.
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Affiliation(s)
- O B Kolcu
- Istinye University, Istanbul, 34010, TR, Turkey.
| | - E Iren
- Mimar Sinan Fine Arts University, Istanbul, 34380, TR, Turkey
| | - T Yetkin
- Mimar Sinan Fine Arts University, Istanbul, 34380, TR, Turkey; Yildiz Technical University, Istanbul, 34220, TR, Turkey
| | - F Özok
- Mimar Sinan Fine Arts University, Istanbul, 34380, TR, Turkey
| | - M N Erduran
- Istanbul Sabahattin Zaim University, Istanbul, 34303, TR, Turkey
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Park C, Kim S, Melis A, Lee W, Elmughrabi A, Cho S, Yeom JY. Scintillation characteristics of chemically processed Ce:GAGG single crystals. PLoS One 2023; 18:e0281262. [PMID: 36881579 PMCID: PMC9990913 DOI: 10.1371/journal.pone.0281262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 01/19/2023] [Indexed: 03/08/2023] Open
Abstract
We investigated the correlation between the surface finish and luminescence properties of chemically polished cerium-doped single-crystal Gd3Al2Ga3O12 scintillators (Ce:GAGG), from the crystallographic perspective. The intrinsic defects in the crystals were identified via photoluminescence spectroscopy followed by scanning electron microscopy and X-ray diffraction to analyze their surface morphologies. Finally, the samples were individually wrapped with an enhanced specular reflector (ESR), coupled with a photomultiplier tube, placed inside a dark box, connected to a digitizer, and irradiated with a 137Cs radioactive source to evaluate the relative light (signal) output and energy resolution of each sample. The as-cut (rough) Ce:GAGG single-crystal samples, that were chemically polished with phosphoric acid at 190°C in air for 60 min, demonstrated a 33.1% increase in signal amplitude (light output to photosensor) and 2.4% (absolute value) improvement in energy resolution, which were comparable to those obtained for the mechanically polished sample. For these samples, the surface roughness was found to be ~430 nm, which was approximately half of that of the mechanically polished sample. The chemical polishing method used in this study is a cost-effective and straightforward technique to improve structural imperfections and can facilitate the treatment of inorganic scintillators with complex shapes and/or on a large scale.
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Affiliation(s)
- Chansun Park
- BK21 Four R&E Center for Precision Public Health, Korea University, Seoul, Republic of Korea
- School of Biomedical Engineering, Korea University, Seoul, Republic of Korea
- Interdisciplinary Program in Precision Public Health, Korea University, Seoul, Republic of Korea
| | - Sangsu Kim
- Global Health Technology Research Center, Korea University, Seoul, Republic of Korea
| | - Alima Melis
- Interdisciplinary Program in Precision Public Health, Korea University, Seoul, Republic of Korea
- Department of Bioengineering, Korea University, Seoul, Republic of Korea
| | - Wonhi Lee
- Interdisciplinary Program in Precision Public Health, Korea University, Seoul, Republic of Korea
- Department of Bioengineering, Korea University, Seoul, Republic of Korea
| | - Abdallah Elmughrabi
- Interdisciplinary Program in Precision Public Health, Korea University, Seoul, Republic of Korea
- Department of Bio-Microsystem Technology, Korea University, Seoul, Republic of Korea
| | - Shinhaeng Cho
- Department of Radiation Oncology, Chonnam National University Medical School, Gwangju, Republic of Korea
- * E-mail: (JYY); (SC)
| | - Jung-Yeol Yeom
- School of Biomedical Engineering, Korea University, Seoul, Republic of Korea
- Interdisciplinary Program in Precision Public Health, Korea University, Seoul, Republic of Korea
- Department of Bioengineering, Korea University, Seoul, Republic of Korea
- * E-mail: (JYY); (SC)
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Kang HG, Kim KJ, Kamada K, Yoshikawa A, Yoshida E, Nishikido F, Yamaya T. Optimization of GFAG crystal surface treatment for SiPM based TOF PET detector. Biomed Phys Eng Express 2022; 8. [PMID: 35180713 DOI: 10.1088/2057-1976/ac56c6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 02/18/2022] [Indexed: 11/12/2022]
Abstract
Coincidence timing resolution (CTR) is an important parameter in clinical positron emission tomography (PET) scanners to increase the signal-to-noise ratio of PET images by using time-of-flight (TOF) information. Lutetium (Lu) based scintillators are often used for TOF-PET systems. However, the self-radiation of Lu-based scintillators may influence the image quality for ultra-low activity PET imaging. Recently, a gadolinium fine aluminum gallate (Ce:GFAG) scintillation crystal that features a fast decay time (~55 ns) and no self-radiation was developed. The present study aimed at optimizing the GFAG crystal surface treatment to enhance both CTR and energy resolution (ER). The TOF-PET detector consisted of a GFAG crystal (3.0 × 3.0 × 20 mm3) and a SiPM with an effective area of 3.0 × 3.0 mm2. The timing and energy signals were extracted using a high-frequency SiPM readout circuit and then were digitized using a CAMAC DAQ system. The CTR and ER were evaluated with nine different crystal surface treatments such as partial saw-cut and chemical polishing and the 1-side saw-cut was the best choice among the treatments. The respective CTR and ER of 202±2 ps and 9.5±0.1% were obtained with the 1-side saw-cut; the other 5-side mechanically polished GFAG crystals had respective values which were 18 ps (9.0%) and 1.3% better than those of the all-side mechanically polished GFAG crystal. The chemically polished GFAG crystals also offered enhanced CTR and ER of about 17 ps (8.2%) and 2.1%, respectively, over the mechanically polished GFAG crystals.
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Affiliation(s)
- Han Gyu Kang
- Department of Nuclear Medicine Science, National Institutes for Quantum Science and technology, Imaging Physics Group, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba Japan, Chiba, Chiba, 263-8555, JAPAN
| | - Kyong Jin Kim
- Institute for Materials Research, Tohoku University, 2-1-1, Katahira, Sendai 980 8577, Japan, Sendai, Miyagi, 980-8577, JAPAN
| | - Kei Kamada
- New Industry Creation Hatchery Center, Tohoku University, 2-1-1, Katahira, Aoba-ku,, Sendai, JP, 980-8577, JAPAN
| | - Akira Yoshikawa
- Institute for Materials Research, Tohoku University, 2-1-1, Katahira, Sendai 980 8577, Japan, Sendai, Miyagi, 980-8577, JAPAN
| | - Eiji Yoshida
- Advanced Nuclear Medicine Science, National Institutes for Quantum Science and Technology (QST), 4-9-1 Anagawa, Inage-ku, Chiba, Japan, Chiba, 263-8555, JAPAN
| | - Fumihiko Nishikido
- National Institutes for Quantum and Technology, 4-9-1, Anagawa, Inage-ku, Chiba, Japan, Chiba, Chiba, 263-8555, JAPAN
| | - Taiga Yamaya
- National Institutes for Quantum and Radiological Science and Technology (QST), 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, JAPAN, Chiba, 263-8555, JAPAN
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