Journal of radiological science and technology (대한방사선기술학회지:방사선기술과학)

Korean Society of Radiological Science (대한방사선과학회)
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Variation on Estimated Values of Radioactivity Concentration according to the Change of the Acquisition Time of SPECT/CT

SPECT/CT의 획득시간 증감에 따른 방사능농도 추정치의 변화

  • Kim, Ji-Hyeon (Department of Nuclear Medicine, Seoul Medical Center) ;
  • Park, Hoon-Hee (Department of Radiological Technology, Shingu College) ;
  • Lee, Joo-Young (Department of Radiological Technology, Songho University)
  • 김지현 (서울특별시 서울의료원 핵의학과) ;
  • 박훈희 (신구대학교 방사선과) ;
  • 이주영 (송호대학교 방사선과)
  • Received : 2021.10.26
  • Accepted : 2021.12.10
  • Published : 2021.12.31
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Abstract

With the recent development of precision medicine(Theranostics), interest and utilization of the quantitative function of SPECT/CT are increasing. This study aims to investigate the effect on the radioactivity concentration estimate by the increase or decrease in the total time of SPECT/CT imaging conditions. A standard image was obtained by the conditions of a total acquisition time of 600 sec(10 sec/f × 120 frames) by diluting 99mTc 91.76 MBq in a cylindrical phantom filled with sterile water, and a comparative image was obtained by increasing the total acquisition time by -90%, -75%, -50%, -25%, +50%, +100%. The CNR, radioactive concentration estimate(cps/ml), and the variation rate(%) of the recovery coefficient(RC) were analyzed by measuring the overall coefficient of interest in each image. The results[CNR, Radiation Concentration, RC] by the change in the number of projections for each increase or decrease rate(-90%, -75%, -50%, -25%, +50%, +100%) of total acquisition time are as follows. [-89.5%, +3.90%, 1.04] at -90%, [-77.9%, +2.71%, 1.03] at -75%, [-55.6%, +1.85%, 1.02] at -50%, [-33.6%, +1.37%, 1.01] at -25%, [-33.7%, +0.71%, 1.01] at +50%, [+93.2%, +0.32%, 1.00] at +100%. and also The results[CNR, Radiation Concentration, RC] by the acquisition time change for each increase or decrease rate(-90%, -75%, -50%, -25%, +50%, +100%) of total acquisition time are as follows. [-89.3%, -3.55%, 0.96] at -90%, [-73.4%, -0.17%, 1.00] at -75%, [-49.6%, -0.34%, 1.00] at -50%, [-24.9%, 0.03%, 1.00] at -25%, [+49.3%, -0.04%, 1.00] at +50%, [+99.0%, +0.11%, 1.00] at +100%. Image quality(CNR) showed a pattern of change in proportion to the increase or decrease in the total acquisition time of SPECT/CT, but the result at quantitative evaluation showed a change of less than 5% in all experimental conditions, maintaining quantitative accuracy(RC less than 0.05) without much influence.

Keywords

Acknowledgement

This work was supported by the research fund of Songho University(SH-2020-A)

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