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The preliminary study aims to investigate whether variation on dose activity 18 F-FDG will influence the overall PET image quality in oncology patients. This is a retrospective analysis of 10 oncology patients who were injected with an average of 337.40 ± 38.43 MBq of 18 F-FDG for PET/CT whole body examination. Patients were divided into 2 groups based on total activity of 18 F-FDG injected: less than 333 MBq (302.96±12.65 MBq) (group 1) and more than 333 MBq (371.85±14.00 MBq) (group 2). Multiple Image Projection (MIP) PET images were scored visually by two qualified nuclear radiologists using a two-point scoring scale (poor and excellent). The agreement between radiologists was analysed using kappa measure of agreement (K). The prediction on poor-to-excellent PET image by the total activity of 18 F-FDG injected was analysed using a Chi-squared test (x 2 ). A p value of < 0.05 was considered significant. Agreement on PET image scoring was substantial, with a kappa value of 0.737. However, the prediction of the PET image quality by the total activity injected has been found to be insignificant (p > 0.05). Therefore, there is no strong evidence suggest that the dose injected will influence the PET image quality. Hence, it is recommended to use low-dosed of 18 F-FDG technique as it also potentially yields a comparable PET image and reduces radiation burden to the patients.

Objective: The goal of this preliminary work was to observe the impact of the prolonged reduced-pressure condition prior to labeling stage on the F-18 Fluorocholine labeling yield at the end of synthesis.Methods: At this present work, the condition inside the reactor vial prior to labeling stage was manipulated. In the first technique of syntheses of F-18 Fluorocholine, the condition inside the reactor vial was set at 0 atmospheric pressure (0 atm) while in the second technique the condition inside the reactor was set at reduced-pressure (between-0.65 to-0.85 bars) with the delay time of 120 seconds. At the end of the synthesis, the impact of the prolonged reduced-pressure condition prior to precursor labeling was measured in terms of labeling yield of F-18 Fluorocholine. Results: With the second technique, the labeling yield of F-18 Fluorocholine was elevated from 9.7% (the first technique) to 24.3%.Conclusion: This preliminary work indicates that delay in a reduced-pressure condition prior to labeling step has greatly improved the labeling yield of F-18 Fluorocholine at the end of synthesis. Using this approach, the labeling yield of F-18 Fluorocholine was elevated from 7.5% to 24.3%.