|
KMID : 0861420120160010034
|
|
Korean Journal of Nuclear Medicine Technology
2012 Volume.16 No. 1 p.34 ~ p.37
|
|
|
Quantitative Evaluation on Optimal Scan Time of PET/CT Studies Using TOF PET
|
|
Moon Il-Sang
Lee Hong-Jae
Kim Jin-Eui
Kim Hyun-Joo
|
|
|
Abstract
|
|
|
Purpose: To verify the optimal scan time per bed for clinical application, we evaluated the quality of 18F-FDG
images with varying scan times in a phantom and 20 patients with 38 lesions using a Philips (TOF) PET/CT scanner.
Materials and Methods: The PET/CT images of a NEMA IEC body phantom and 20 patients (16 males, 4 females) were acquired for 5 different scan times of 20-100 sec per bed with intervals of 20 sec. The activity ratio of hot spheres (diameter of 17 [H1], 22 [H2] and 28 [H3] mm) to the background region in the IEC body phantom was 8-to-1. The contrast recovery coefficient (CRC) and standard uptake value (SUV) based on ROIs of hot spheres and background region were calculated. The noise in each background region was estimated as the ratio of SD of counts to the mean counts in the background region. On the patient image, the injected dose of 18F-FDG was 444±74 MBq and the SUVs in the 38 hot lesions were measured.
Results: The two scan time groups (LT-60 [<60 sec] and GT-60 [≥60 sec]) were compared. In the phantom study, the coefficient of deviations (CVs, %) of CRC and SUV in LT-60 (H1: 14.2 and 7.3, H2: 11.4 and 7.8, H3: 4.9 and 3.2) were higher than GT-60 (H1: 8.9 and 2.8, H1: 8.2 and 5.0, H3: 2.0 and 1.6). In the patient study, the mean CV of CRC and
SUV in LT-60 (4.0) was higher than GT-60 (1.2).
Conclusion: This study showed that noise increased as the scan time decreased. High noise for the scan time <60 sec per bed yielded high variation of SUV and CRC. Therefore, considering PET/CT image quality, the scan time per bed in the TOF PET/CT scanner should be at least ≥60 sec.
|
|
|
KEYWORD
|
|
|
SUV, CRC, scan time, LT-60, GT-60
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|
|