DocumentCode :
1717506
Title :
A study of coincidence line spread function (CLSF) estimation for small scintillators using quadrant sharing technique
Author :
Aykac, Mehmet ; Li, Hongdi ; Uribe, Jorge ; Wang, Yu ; Baghaei, Hossain ; Liu, Yaqiang ; Xing, Tao ; Wong, Wai-Hoi
Author_Institution :
M.D. Anderson Cancer Center, Texas Univ., Houston, TX, USA
Volume :
4
fYear :
2001
fDate :
6/23/1905 12:00:00 AM
Firstpage :
1941
Lastpage :
1946
Abstract :
Inter-crystal scatter is one of the primary reasons to misplace the coincidence events in positron emission tomography (PET). The probability of Compton scattering of a 511 KeV photon within the crystal is more than 50% of all interactions. Unlike one-to-one scintillator-photomultiplier tube (PMT) coupled (discrete) detectors, detector blocks utilizing the light sharing technique must have an additional degradation on their spatial resolution due to shared scintillation photons within the block. This study focuses on an estimation of the coincidence line spread function (CLSF) for 7×7 BGO (bismuth germanate) detector blocks by comparing the simulation results for discrete and light shared detectors. Based on experimental measurements, decoding probabilities, which describe the uncertainty in positioning between neighboring crystals, were estimated from photoelectron statistics. The results were embedded into the Monte Carlo simulation to estimate the CLSF more accurately. In this study, two 7×7 BGO detector blocks (2.68 mm×2.68 mm×18 mm) with different surface treatments coupled to 4 PMTs were used to estimate the decoding probability values. For discrete detectors, the FWHM values of CLSF for 7×7 BGO block with crystal dimensions of 2.68 mm×2.68 mm×18 mm were approximately found 1.47 mm for discrete detectors and 1.51 mm for light shared detectors. The intrinsic spatial resolutions of 7×7 light shared BGO block with crystal dimensions of 2.68 mm×2.68 mm×18 mm for 20 cm, 40 cm and 80 cm detector ring diameters were projected to 1.57 mm, 1.75 and 2.30 mm, respectively. Making the assumption that LSO (lutetium orthosilicate) crystals have 5 times more light output than BGO, 14×14 LSO block with crystal dimensions of 1.32 mm×1.32 mm×20 mm can be decoded and intrinsic spatial resolutions for 20 cm, 40 cm and 80 cm detector ring diameters were expected to be 0.87 mm, 1.15 mm and 1.91 mm, respectively
Keywords :
bismuth compounds; medical image processing; positron emission tomography; solid scintillation detectors; BGO detector blocks; Bi2GeO5; Compton scattering; Monte Carlo simulation; PET; coincidence events; coincidence line spread function estimation; discrete detectors; light sharing technique; positron emission tomography; quadrant sharing technique; spatial resolution; Decoding; Degradation; Light scattering; Optical coupling; Particle scattering; Photonic crystals; Positron emission tomography; Probability; Solid scintillation detectors; Spatial resolution;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Nuclear Science Symposium Conference Record, 2001 IEEE
Conference_Location :
San Diego, CA
ISSN :
1082-3654
Print_ISBN :
0-7803-7324-3
Type :
conf
DOI :
10.1109/NSSMIC.2001.1009204
Filename :
1009204
Link To Document :
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