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KMID : 0861420110150020036
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Korean Journal of Nuclear Medicine Technology
2011 Volume.15 No. 2 p.36 ~ p.40
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Evaluation of Reasonable 18F-FDG Injected Dose for Maintaining the Image Quality in 3D WB PET/CT
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Moon A-Reum
Lee Hyuk
Kwak In-Suk
Choi Sung-Ook
Seok Jae-Dong
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Abstract
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Purpose:18F-FDG injected dose to the patient is quite different between the recommended dose from
manufacturer and the actual dose applied to each of hospitals. injection of inappropriate 18F-FDG dose may not
only increase the exposed dose to patients but also reduce the image quality. we thus evaluated the proper
18F-FDG injected dose to decrease the exposed dose to patients considering the image quality. Materials And
Methods:NEMA Nu2-1994 phantom was filled with 18F-FDG increasing hot cylinder radioactivity
concentration to 1, 3, 5, 7, 9 MBq/kg based on the ratio of 4:1 between the hot cylinder and background activity.
after completing the transmission scan using ct, emission scan was acquired in 3D mode for 2 minutes 30
seconds/bed. ROI was set up on hot cylinder and background radioactivity region. after measuring SUVmax those
regions, then analyzed SNR at the points. clinical experiment has been conducted the object of patients who have
came to smc from november 2009 to august 2010, 97 patients without having a hepatic lesions were selected.
ROI was set up in the liver and thigh area. after measuring SUVmax, the image quality was compared following
the injected dose.
Results:in phantom study, as the injected radioactivity concentration per unit mass was 1, 3,
5, 7, 9 MBq/kg, SUVmax was 23.1, 24.1, 24.3, 22.8, 23.6 and SNR was shown 0.48, 0.54, 0.56, 0.55, 0.55.
according to increment of the injected dose, SUVmax and SNR was increased under 5 MBq/kg but they were
decreased over 7 MBq/kg. in case of clinical experiment, as increased the injected radioactivity concentration
per unit mass was 4.72, 5.34, 6.16, 7.41, 8.68 MBq/kg, SUVmax was 2.68, 2.67, 2.26, 1.88, 1.95 and SNR was
shown 0.52, 0.53, 0.46, 0.46, 0.44. if the injected dose exceeds 5 MBq/kg, showed a decrease pattern as phantom
study.
Conclusion:increasing 18F-FDG injected dose considered patient’s body weight improve image quality
within a certain range. if it exceeds the range, it can be reduced image quality due to random and scatter
coincidences. this study indicates that the optimal injected dose was 5 MBq/kg per unit mass the injected
radioactivity concentration in 3d wb pet/ct.
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KEYWORD
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Image quality, signal to noise, standardized uptake value
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