Objective To reconstruct sparse views CT image based on defective projection data.Methods The position of bad bins in detector determined whether the linear interpolation was applied to the defective projection data.Moreover,reconstruction of air pixels in CT image was achieved rapidly and accurately.Results he experimental results showed that the proposed method could solve the problem from classical ART-TV method that the robustness was unstable due to the different positions of bad bin in CT detector.Conclusion Compared to analytical reconstruction methods,iterative methods can solve the reconstruction problems in this modality so that the radiologist is facilitated to perform image processing and quantitative analysis.

Objective: To investigate the pedestrian traffic safety behaviors of primary and secondary school students in Xiacheng District of Hangzhou,and to provide reference for formulating traffic safety strategy. Methods: In October 2015,nine campuses of six schools in Xiacheng District were selected to observe the pedestrian traffic safety behaviors of the primary and secondary school students walking to and from school,such as taking the zebra crossing,observing the traffic condition,running and playing with cellphones when walking across the road. Results: Totally 2 585 students were investigated,and 2 580 students were valid（99.81%）. When walking across the road,1 887 people took the zebra crossing,accounting for 73.14%;71.89% of boys and 74.51% of girls took the zebra crossing,and there was no significant difference（P>0.05）;64.76% and 81.32% of the students took the zebra crossing on the way to school and home,with a significant difference（P<0.05）. When walking across the road,1 683 students people observed the traffic conditions,accounting for 65.23%;63.61% of boys and 67.02% of girls observed the traffic conditions,and there was no significant difference（P>0.05）;64.05% and 66.39% of the students observed the traffic conditions on the way to school and home,with a significant difference（P<0.05）.There were 362 students running across the road, accounting for 14.03%;15.31% of boys and 12.62% of girls ran across the road,and there was no significant difference（P>0.05）;9.26% and 18.68% of the students ran across the road on the way to school and home,with a significant difference（P<0.05）. There were 53 students playing with cellphones when crossing the road,accounting for 2.05%;2.29% of boys and 1.79% of girls played with cellphones,and there was no significant difference（P>0.05）;1.41% and 2.68% of the students played with cellphones on the way to school and home,with a significant difference（P<0.05）. Conclusions Primary and secondary school students have dangerous behaviors when walking across the road. We should focus on the intervention of not taking the zebra crossing and not observing traffic conditions when crossing the road on the way to school,and playing with cellphones on the way home.

Objective: To learn the status of knowledge,attitude and behaviors of road traffic safety in primary and secondary school students in Xiacheng District of Hangzhou. Methods: The students of fourth to seventh grade from seven schools in Xiacheng District were selected and surveyed for their knowledge,attitude and behaviors of road traffic safety by self-designed questionnaires. Results: Totally 4 006（99.98%）students completed the survey,who mostly had awareness rates of over 90% in knowledge about safe behaviors when walking,walking across the road and riding a bicycle or an electric bicycle. The awareness rates of"should not run across the road","should not ride side by side"and"should not ride on the motorway"were relatively low,which were 81.65%,85.72% and 82.78%,respectively. About 68.47% of students thought it necessary to wear a helmet when riding a bicycle or an electric bicycle,72.22% of students thought it necessary to wear seatbelt or use child safety seat when taking a car. The two rates were significantly higher in girls than boys and in primary school students than secondary school students（P<0.05）. The top three unsafe behaviors the students did in the past six months were"not wear a helmet when riding a bicycle or an electric bicycle","run across the road"and"ride on the motorway",the rates of which were 86.84%,10.06% and 7.91%,respectively. Conclusion The knowledge of road traffic safety among primary and middle school students in Xiacheng District is mastered well. Interventions should be focused on unsafe behaviors including not wearing a helmet when cycling,riding on the motorway and running cross the road.