Gamma | The Comparison of Image Quality according to the change of Acquisitio…
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작성자 : 서울대 핵의학과 작성일2017-02-01 조회3,440회관련링크
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Jung Jin Lim1, Sung Wook Jo1, Jin Eui Kim 1 Geon wook Kang1,2
Dept. of Nuclear Medicine, Seoul National Univ. Hospital1
Dept. of Nuclear Medicine, Seoul National Univ.2
[Object] There are several factors that determine image quality in SPECT/CT, such as acquisition time, angle and reconstruction methods. In this study, we focused on only the aspect of acquisition angles and evaluated the image quality by applying four different angles.
[Materials and Methods] This study was carried out with Flangeless Esser PET Phantom (Data Spectrum Corp., USA) and NEMA Triple Line Source Phantom (Data Spectrum Corp, USA) using a SPECT/CT, Discovery 670 (GE, USA). The interior of the Flangeless Esser PET phantom was filled with 37 kBq/mL of 99mTcO - for background setting and
4 of cylinders (8, 12, 16, 25 mm) were filled with 296 kBq/mL of 99mTcO -.; The cylinders
to background activity ratio was regulated as 8:1. The three lines of the NEMA Triple Line Source Phantom were filled with 3.7 MBq/mL of 99mTcO -. Acquisition angles were varied as 3°, 4°, 5° and 6° with the acquisition time fixed on 15 sec/Frame. OSEM algorithm and CT attenuation correction were applied for reconstruction. For comparison, contrast noise to ratios(CNR) and contrast recovery ratio were calculated
from the images of Flangeless Esser PET phantom. Plus, resolution was also measured from the images of NEMA Triple Line Source Phantom.
[Results] In the experiments using Flangeless Esser PET Phantom, there was not a significant change in the contrast recovery ratio(supplement table 1), however the contrast noise to ratio was decreased with the increase of acquisition angle (supplement table 2). In the experiments using NEMA Triple Line Source Phantom, resolution did not change significantly with the increase of acquisition angle (supplement table 3).
[Conclusion] In SPECT/CT images, the contrast to noise ratio was found to be reduced with the increase of acquisition angle while it did not affect the contrast recovery ratio and resolution. Therefore, when performing SPECT/CT, it is necessary to adjust the acquisition angle according to the type of study, and it is also recommended to perform additional experiments to find a suitable acquisition angle.