Objective To measure and analyze Varian Clinac 21EX accelerator induced radioactivity,and to provide specific recommendations and ways of radiation protection for radiotherapy technicians.Methods To simulate the working environment of radiotherapy technician,and to detect induced radioactivity variation of Varian Clinac 21EX accelerator that induced by 15 MV X-rays under different conditions of beam field area,dose,time,distance and by high energy electron beam (12,16,20 MeV)at the different time.Results The induced radioactivity level was not influenced by different beam field area,and was increased with increasing dose (r =0.930,P ＜ 0.05),decreased with time increase (r =-0.84,P ＜ 0.05),decreased with distance increase(r =-0.975,P ＜ 0.05).The induced radioactivity attenuation levels of the different doses at the same time are different,and have the common characteristic that the induced radioactivity attenuation rate is faster in the initial times.The induced radioactivity levels of high energy electron beams were significantly lower than those of high-energy X-rays.Conclusions During radiotherapy positioning,it is necessary to take measures to protect against the induced radioactivity when high-energy rays with energy greater than 10 MeV will be used.The radiotherapy technician should take the different time and energy interval steps for the different ray type and energy and dose in order to meet the radiation protection principle of optimization.

Objective To explore the relationship of X-ray exposure parameters and false-node rate during image-guidance treatment with CyberKnife spine tracking.Methods Using spine tracking planning on a chest phantom,several combinations of X-ray exposure parameters were used to locate.The false-node ratio and the surface absorbed dose were investigated and the radiation dose was optimized.Results The false-node ratio and surface absorbed radiation dose decreased when the X-ray exposure parameters increased until they saturated.In the range of ≤5.0％ false-node rate,the surface absorbed radiation dose was 0.11,0.26 mGy,and 0.31-0.46 mGy,when the false-node rate was 2.77％,1.07％and 1.0％,respectively.Conclusions In image-guided treatment of CyberKnife,the radiation dose would be optimized,and the patient's radiation dose would be reduced greatly,which is important to protect the patients.

CHO cells expressing human GPIb/IX and rabbit red blood cells coated with human von Willebrand factor (VWF) were adapted to our study on the binding probability and the detachment force of GPIb/IX and VWF. With the micropipette system, the two cells were impinged under a constant force for controlled time. When the cells were pulled apart, the deformation of RBC was recorded, and the binding score and detachment force of the proteins were determined. After the two cells were impinged into 0.5 microm for 30 s, the binding probability of the two cells carrying GPIb/IX and VWF was 15.0%. Via analyzing the deformation of red blood cells, we found out the distribution of rupture forces of cells with GPIb/IX and VWF. Therefore, we infer that the continuous distribution of the detachment force is due to the stochastic effect. The most probable value of the detachment force was 10 pN.
Animals ; Binding Sites ; Blood Platelets ; metabolism ; CHO Cells ; Cell Adhesion ; Cricetinae ; Cricetulus ; Humans ; Platelet Activation ; physiology ; Platelet Glycoprotein GPIb-IX Complex ; chemistry ; metabolism ; Rabbits ; von Willebrand Factor ; chemistry ; metabolism

ObjectiveTo investigate the pharmacokinetic characteristics of sofosbuvir tablets, and to evaluate the bioequivalence and safety of two preparations. MethodsHealthy volunteers were recruited through the platform of clinical trial recruitment in The Affiliated Hospital of Changchun University of Chinese Medicine. Screening physical examination was performed for fasting group on September 18, 2018 and for postprandial group on September 28, 2018, and the volunteers were enrolled after their physical examination results met the inclusion criteria. The fasting group and the postprandial group, with 40 volunteers in each group, were given oral administration of the test preparation sofosbuvir tablets or the reference preparation sofosbuvir tablets (SOVALDI, 400 mg). This was a randomized, open-label, two-sequence, four-cycle, single-dose, and completely repeated cross-over bioequivalence test in the fasting or postprandial state in the healthy population; in the fasting group, 20 volunteers each received oral administration of the test preparation and the reference preparation, and in the postprandial group, 20 volunteers each received oral administration of the test preparation and the reference preparation. Liquid chromatography-tandem mass spectrometry was used to measure the content of sofosbuvir and its major metabolite GS-331007 in human EDTA-K2 plasma; the plasma concentration of sofosbuvir was measured at 15 time points from 0 hour to 8 hours after administration, and that of GS-331007 was measured at 16 time points from 0 hour to 72 hours after administration. WinNonlin software was used to calculate pharmacokinetic parameters and evaluate bioequivalence. ResultsAfter the administration of the test preparation and the reference preparation in the fasting state, when the pharmacokinetic parameters of sofosbuvir was used to evaluate the bioequivalence of the test preparation and the reference preparation, the ratios of the geometric means of Cmax, AUC0-t, and AUC0-inf were 90.55%, 97.26%, and 94.62%, respectively; when the pharmacokinetic parameters of GS-331007 was used to evaluate the bioequivalence of the test preparation and the reference preparation, the ratios of the geometric means of Cmax, AUC0-t, and AUC0-inf were 98.91%, 98.98%, and 99.46%, respectively. All of the above values were within the range of 80.00%-125.00%. An analysis of variance was performed after the pharmacokinetic parameters of sofosbuvir Cmax, AUC0-t, and AUC0-inf were transformed by natural logarithm, and the results showed that sequence, cycle, and preparation had no marked influence on Cmax, AUC0-t, and AUC0-inf (all P＞0.05). ConclusionThe test preparation of sofosbuvir tablets is bioequivalent to the reference preparation in the fasting and postprandial states.