Objective:To evaluate the effects of split-filter dual-energy CT (SF-DECT) in improving image quality at low doses in the process of abdominal examinations for children.Methods:A preliminary study was conducted using child phantoms. Furthermore, 20 children aged 4-6 years were recruited prospectively for clinical validation from June 2020 to December 2020. Conventional single-energy CT (SECT) and SF-DECT were employed to scan the abdominal areas of the phantoms and children. Then, the CT values, image noise, contrast to noise ratios (CNRs), and image subjective scores of SF-DECT and SECT were compared under various doses (1, 2, 3, and 4 mGy).Results:For the phantoms under doses of 3 and 4 mGy, SF-DECT decreased the image noise by 18.9% and 23.6%, respectively, and increased the liver and kidney CNRs (CNR liv and CNR kid) by 12.8% and 31.9% at most, respectively, compared to SECT ( Z = 3.00, 5.17, P < 0.001). For children, SF-DECT decreased image noise ( Z = 4.64, P < 0.001) and increased CNR liv and CNR kid ( Z = 3.78, 3.39, P < 0.001). For both the phantoms and the children, the subjective scores of images scanned using the SF-DECT were higher than those scanned using the SECT ( Z = 1.96-3.80, P < 0.05). Conclusions:Compared with SECT, SF-DECT can improve the quality of children′s abdominal images. This technique has a certain prospect of optimizing abdominal CT for children. However, it is necessary to conduct in-depth clinical research to verify the result.

Objective: To investigate adolescent haze weather health protection behavior, and to provide scientific basis for behavioral intervention and health guidance for adolescents in haze weather. Methods: From June 2015 to April 2016, 1 025 adolescents were selected from 22 classes in two middle schools of Baoding City, Hebei Province, by stratified cluster sampling method. General information questionnaire and the Brief Haze Weather Health Protection Behavior Assessment Scale Adolescent Version (BHWHPBAS AV) were used. Multiple linear regressions were conducted to explore factors affecting adolescent haze weather health protection behavior. Different models were used to confirm associations between influencing factors and BHWHPBAS AV scores. Results: Adolescents had a low overall score of BHWHPBASAV (45.81±13.16). The score rate of self adjustment after haze weather was the highest (64.54%). The score rate of obtaining relevant knowledge before haze weather was the lowest (50.28%). Compared with adolescents in urban area, rural adolescents had a lower BHWHPBAS AV score ( β=-3.20, P <0.01). Compared with students (living with parents), those living without parents had a lower BHWHPBAS AV score ( β=-4.16, P =0.01). Compared with students never receive physical examination,those had received physical examination during the past years had a higher BHWHPBAS AV score ( β=4.44，5.66，9.04, P <0.01). Compared with students with no knowledge of respiratory system diseases, those with moderate to sufficient knowledge had a higher BHWHPBAS AV score ( β=9.34，12.19，P <0.01). These associations were stable and consistent.Multiple linear regression analysis showed that residence, residence with parents, physical examination and knowledge of respiratory diseases were the relevant factors of BHWHPBAS AV score ( P <0.05). Conclusion Adolescent haze weather health protection behavior level is low and is affected by many factors. Cooperation should be strengthened to conduct behavioral interventions and health guidance on haze health protection for adolescents, so as to promote healthy growth of adolescents.