Image quality and lesion detectability in low-dose pediatric 18F-FDG scans using total-body PET/CT.

PURPOSE: To investigate the effects of dose reduction on image quality and lesion detectability of oncological 18F-FDG total-body PET/CT in pediatric oncological patients and explore the minimum threshold of administered tracer activity. METHODS: A total of 33 pediatric patients (weight 8.5-58.5 kg; age 0.8-17.6 years) underwent total-body PET/CT using uEXPLORER scanner with an 18F-FDG administered dose of 3.7 MBq/kg and an acquisition time of 600 s were retrospectively enrolled. Low-dose images (0.12-1.85 MBq/kg) were simulated by truncating the list-mode PET data to reducing count density. Subjective image quality was rated on a 5-point scale. Semi-quantitative uptake metrics for low-dose images were assessed using region-of-interest (ROI) analysis of healthy liver and suspected lesions and were compared with full-dose images. The micro-lesion detectability was compared among the dose-dependent PET images. RESULTS: Our analysis shows that sufficient subjective image quality and lesion conspicuity could be maintained down to 1/30th (0.12 MBq/kg) of the administered dose of 18F-FDG, where good image quality scores were given to 1/2- and 1/10- dose groups. The image noise was significantly more deranged than the overall quality and lesion conspicuity in 1/30- to 1/10-dose groups (all p < 0.05). With reduced doses, quantitative analysis of ROIs showed that SUVmax and SD in the liver increased gradually (p < 0.05), but SUVmax in the lesions and lesion-to-background ratio (LBR) showed no significant deviation down to 1/30-dose. One hundred percent of the 18F-FDG-avid micro-lesions identified in full-dose images were localized down to 1/15-dose images, while 97% of the lesion were localized in 1/30-dose images. CONCLUSION: The total-body PET/CT might significantly decrease the administered dose upon maintaining the image quality and diagnostic performance of micro-lesions in pediatric patients. Data suggests that using total-body PET/CT, optimal image quality could be achieved with an administered dose-reduction down to 1/10-dose (0.37 MBq/kg).

[Study on optimal model of hypothetical work injury insurance scheme].

OBJECTIVE: To explore an optimal model of hypothetical work injury insurance scheme, which is in line with the wishes of workers, based on the problems in the implementation of work injury insurance in China and to provide useful information for relevant policy makers. METHODS: Multistage cluster sampling was used to select subjects: first, 9 small, medium, and large enterprises were selected from three cities (counties) in Zhejiang Province, China according to the economic development, transportation, and cooperation; then, 31 workshops were randomly selected from the 9 enterprises. Face-to-face interviews were conducted by trained interviewers using a pre-designed questionnaire among all workers in the 31 workshops. RESULTS: After optimization of hypothetical work injury insurance scheme, the willingness to participate in the scheme increased from 73.87%to 80.96%; the average willingness to pay for the scheme increased from 2.21% (51.77 yuan) to 2.38% of monthly wage (54.93 Yuan); the median willingness to pay for the scheme increased from 1% to 1.2% of monthly wage, but decreased from 35 yuan to 30 yuan. The optimal model of hypothetical work injury insurance scheme covers all national and provincial statutory occupational diseases and work accidents, as well as consultations about occupational diseases. The scheme is supposed to be implemented worldwide by the National Social Security Department, without regional differences. The premium is borne by the state, enterprises, and individuals, and an independent insurance fund is kept in the lifetime personal account for each of insured individuals. The premium is not refunded in any event. Compensation for occupational diseases or work accidents is unrelated to the enterprises of the insured workers but related to the length of insurance. The insurance becomes effective one year after enrollment, while it is put into effect immediately after the occupational disease or accident occurs. CONCLUSION: The optimal model of hypothetical work injury insurance scheme actually realizes cross-regional mobility of workers, minimizes regional differences, and embodies the fairness. The proposed model will, to some extent, protect the rights and interests of enterprises, as well as the healthy rights and interests of workers when they are unemployed.