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Objective@#To investigate the duration of Norovirus (NoV) shedding among infected school children during a NoV outbreak in a kindergarten,and to provide scientitic basis for epidemic prevention and control.@*Methods@#Specimens and epidemiological data were collected from suspected cases, and specimens were detected using real-time RT-PCR to determine whether or not infecting with NoV. Specimens were collected every 3-7 days from NoV-infected children until specimens became negative for NoV.@*Results@#A total of 14 suspected cases were reported, and 12 of them were infected with NoV. The average duration of NoV shedding was (26.58±17.94)d. The specimens among 9 from 12 Nov-infected cases were positive at 7 days, 8 NoV-intected cased remained positive at 14 days and 7 Non-infected cased at least 21 days.@*Conclusion@#Since NoV shedding duration among NoV-infected children tends to longer than their isolation time during outbreaks, reinforcement of hygiene practices among these school children is especially necessary to reduce the risk of virus secondary transmissions after their return to school.
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The Major of Medical Imaging Technology (Radiotherapy Technology Orientation) in West China Medical School, Sichuan University, has been devoted to training therapists, dosimetrists, and physicists in tumor radiotherapy, and it is urgently needed to improve the practice ability of interns and standardize the teaching system. In view of the current status of the practice of students in radiotherapy technology, this article analyzes and summarizes the teaching staff construction, teaching contents, teaching methods, and other aspects, finds out the problems and challenges in the current teaching system, and puts forward suggestions for practice teaching reform.
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Objective To evaluate the feasibility of an in-room automated volumetric arc therapy (VMAT) planning engine based on dose volume histogram (DVH) prediction model in RayStation treatment planning system.Methods A total of 4,0 VMAT plans of cervix cancer,planned by experts,were chosen to build DVH estimation model by principal component regression analytic method.An in-room automated VMAT planning program based on IroPython scripting language combined with DVH prediction model was performed in RayStation treatment planning system.The DVH estimation model was applied to Another 10 testing cases of cervical cancer and the feasibility was evaluated by comparing the automatic plans with manual plans.Results The predicted DVH of organs at risk showed a good fit with real DVH in the ten testing cases.There were no statistically significant differences between manual and automatic plans in PTV conformal index (CI) and homogeneity index (HI) (P ＞ O.05).V40 and V50 of bladder were significantly decreased by 4.3％ and 1.6％ in automatic plans (t =2.75,5.26,P ＜ 0.05).V30,V40 and Vs0 of rectum were also decreased by 6.8％,5.8 ％ and 2.1％ (t =2.26,3.55,5.19,P ＜ 0.05).Both left and right femoral heads were better spared in automatic plans with average doses decreased by 380 and 322 cGy(t =5.55,7.25,P ＜ 0.05).The time of creating a treatment plan was 36 min for automatic plan and 53 min for manual plan.Conclusions The fully automated VMAT treatment plan program can create a VMAT plan of cervix cancer with high efficiency and good quality.
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Objective To analyze the displacement of titanium clips for tumor bed localization after breast-conserving surgery for breast cancer and its influential factors.Methods A retrospective analysis was performed on the cone-beam computed tomography (CT) images of 14 patients with breast cancer who received radiotherapy after breast-conserving surgery from April to October,2016.The relative position of the chest wall and the errors of the titanium clips in radiotherapy were measured.A Pearson correlation analysis was used to analyze the correlation of the displacement of titanium clips with the relative position of titanium clips,the breast volume,the vertical distance between the titanium clips and the tangential line of the chest wall,and the maximum thickness of the breast.Results The system errors of the chest wall in left-right,superior-inferior,and anterior-posterior directions were 4.42,3.44,and 5.13 mm,respectively,and the random errors were 3.55,3.07,and 4.54 mm,respectively.The titanium clips had a large displacement relative to the chest wall,mainly in the left-right direction.The maximum system error was 4.39 mm and the random error was 2.42 mm.The displacement of titanium clips was not significantly correlated with the breast volume and the maximum thickness of the breast (P>0.05).However,the relative position of titanium clips in superior-inferior direction was significantly correlated with the displacement of the lowest,the most lateral,the most anterior,and the most posterior titanium clips (P<0.05).As to the uppermost clips,there was a significant difference in displacement between the clips close to the chest wall and the clips far from the chest wall (P=0.02).Conclusions Due to large setup error and displacement of titanium clips during radiotherapy,simultaneous integrated boost is not suitable for patients with breast cancer who are immobilized by vacuum cushion and received radiotherapy.The unstable immobilization may be the major influential factor for the displacement of titanium clips.
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Objective To study the killing effect of polymorphonuclear neutrophils(PMNs) on Trichomonas vaginalis. Methods The vaginal secretion from a patient with vaginitis was incubated in the liver infusion liquid medium to get T. vaginalis. One ml serum was collected from the patient and heated for 30 min at 56 ℃ to inactivate complement in serum, and was absorbed three times with the parasites at 0 ℃ to make the serum free of antibodies. PMNs were separated from the patient’s blood and purified with density gradient centrifugation and polymer accelerating sedimentation. NBT and safranin O were used to stain the sample. The interaction between PMNs and the parasites was observed under microscope. 300 trichomonads and 3?104 PMNs were incubated for 10, 20, 30, 40, 50, 60 minutes under the conditions of aerobic or anaerobic, with superoxide dismutase (SOD) and catalase (CAT) or without SOD and CAT, and with complement or without complement. They were then inoculated in solid medium for another five days under the anaerobic condition, and surviving organisms were enumerated. Results PMNs were observed to surround and kill a single trichomonad. In the petri-dish containing PMNs, the surviving rate of the parasites in anaerobic condition was 85%, only 3% in aerobic condition (P