PET/CT에서 Phantom을 이용한 Fluorine-18, Gallium-68 방사성 핵종의 PET 영상 평가

Evaluation of PET Image for Fluorine-18 and Gallium-68 using Phantom in PET/CT

The purpose of this study is to compare PET imaging performance with Fluorine-18 ( 18 F) and Gallium-68 ( 68 Ga) for influence of physical properties of PET tracer. Measurement were performed on a Siemens Biograph mCT64 PET/CT scanner using NEMA IEC body phantom and Flangeless Esser PET phantom containing filled with 18 F and 68 Ga. Emission scan duration(ESD) was set to 1, 2, 3, 4 and 5min/bed for 68 Ga and 1min/bed for 18 F. The PET image were evaluated in terms of contrast, spatial resolution. Under same condition, The percentage of contrast recovery measured in the phantom ranged from 16.88% to 72.56% for 68 Ga and from 27.51% to 74.43% for 18 F and The FWHM value to evaluate spatial resolution was 10.96 ㎜ for 68 Ga and 9.19 ㎜ for 18 F. For this study, 18 F produces better image contrast and spatial resolution than 68 Ga due to higher positron yield and lower positron energy ( 18 F: 96.86%, 633.5 keV, 68 Ga: 88.9%, 1899 keV), The physical properties of PET tracer effect on the PET image. 68 Ga image applying ESD of 3, 4, 5min/bed were showed similar to 18 F image with ESD of 1min/bed. This study suggests that increasing ESD for acquiring 68 Ga PET image seem to be similar to 18 F image.