Investigation on the influence of dose minimisation management on the PET image quality

The issue of balancing patient's dose radiation and image quality improvement possesses an interesting argument in PET/CT practices where newer technologies evolved one after another and increased demands from referring physicians. Therefore, this study aims to demonstrate that a reasonable-to-excellent PET image could be achieved via implementation of low dose of 18F-FDG/kg administered. A total number of 50 patients (34 men, 16 women, age 53.8 ± 14.05 years) who were injected with an activity ranging from 4.19 to 7.98 MBq/kg (5.80 ± 0.90 MBq/kg) of 18F-FDG for PET/CT whole body examination were evaluated retrospectively. Image quality was scored visually by two nuclear radiologists using a three-point scoring scale (poor, reasonable and excellent). COV values measured in a right lobe of liver (ROI: 2–5 cm3) were recorded and calculated as a parameter reflecting noise. The prediction of the PET image quality adopting 18F-FDG dose of <6 MBq/kg obtained in 32 patients versus those with >6 MBq/kg, was significant (p < 0.05). Interestingly, at dose >6 MBq/kg, higher noise were observed with COV averaged of 27.4% whereas COV averaged of 25.7% were observed for dose at <6 MBq/kg. Therefore, it is suggested that a reasonable-to-excellent PET image quality could be achieved by administration of 18F-FDG dose of <6 MBq/kg in the vast majority of patients when using an LSO PET camera and applying a 2 min per bed position acquisition protocol.