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KMID : 1143620130170010025
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Korean Journal of Nuclear Medicine Technology
2013 Volume.17 No. 1 p.25 ~ p.29
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Accuracy Evaluation of CT-Based Attenuation Correction in SPECT with Different Energy of Radioisotopes
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Kim Seung-Jeong
Kim Jae-Il
Kim Jung-Soo
Kim Tae-Yeob
Kim Soo-Mi
Woo Jae-Ryong
Lee Jae-Sung
Kim Yu-Kyeong
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Abstract
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Purpose: In this study, we evaluated the accuracy of CT-based attenuation correction (AC) under the conventional CT protocol (140 kVp, on average 50-60 keV) by comparing the SPECT image qualities of different energy of radioisotopes, 201Tl, 99mTc and 131I.
Materials and Methods: Using a cylindrical phantom, three different SPECT scans of 201Tl (70 keV, 55.5 MBq), 99mTc (140 keV, 281.2 MBq) and 131I (364 keV, 96.2 MBq) were performed. The CT image was obtained with 140 kVp and 2.5 mA in GE Hawkeye 4. The OSEM reconstruction algorithm was performed with 2 iterations and 10 subsets. The experiments were performed in the 4 different conditions; non-AC and non-scatter correction (SC), only AC, only SC, AC and SC in terms of uniformity and center to peripheral ratio (CPR).
Results: The uniformity was calculated from the uniform whole region in the reconstructed images. For 201Tl and 99mTc, the uniformities were improved by about 10-20% AC was applied, but these were decreased by about 2% as SC was applied. The uniformity of 131I was slightly increased as both AC and SC were applied. The CPR of the reconstructed image was close to one, when AC was applied for 201Tl and 99mTc scans and 131I was distant from 1 and that is only AC.
Conclusion: The image uniformity improved by AC on low energy likely to 201Tl and 99mTc. However, image uniformity of high energy such as 131I was improved, when both AC and SC was applied.
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KEYWORD
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Attenuation correction, Scatter correction, Uniformity, Center to peripheral ratio
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