Objective:To establish a rapid and precise dose measurement method with EBT4 film and ensure its measurement accuracy to be within the required range through strict operational procedures for the purpose of addressing the two essential issues of poor measurement accuracy and timeliness of EBT film under FLASH conditions.Methods:After storing under different humidity conditions for a certain period of time, the film was exposed to radiation for analyzing the influence of air humidity on the intrinsic performance of EBT film. By means of repeated scanning operations and the film angle rotation, the influences of repeated scanning and film placement angle were analuzed. Parabolic correction method was used to reduce the spatial position influence during the scanning process. By analying the relationship between net optical density (netOD) and absorbed dose through the comparison of three fitting method, the optimal fitting curve was selected. After irradiation of the same batch of films for 5 min and 24 h, the film doses were calibrated and then compared with ionization chamber-measured result. The rapid and precise film dosimetry method was used to measure both the percentage depth dose from X-rays at ultra-high dose rate and the dose distribution at a depth of 2 cm in water.Results:Air humidity had the greatest influence on the intrinsic performance of EBT film (approximately 20%). The average deviation of repeated scans is within 0.5%. The angle at which the film is placed significantly affected the readouts of the film with the maximum influence approximately 70%. The net optical density combined with polynomial fitting can control the fitting residuals of 1-16 Gy within 3%. The change rate of light channels at 5 min already mostly met the requirements of the rapid mode (< 0.5%). Compared with the measurement result obtained using the reference ionization chamber, the deviations of the 5 min or 24 h dose calibration curves were all within 2%.Conclusions:The EBT4 film can be employed as a precise dosimeter to quickly measure the FLASH radiation dose. Rapid and precise FLASH dose measurements can meet the stringent requirements of both preclinical and clinical FLASH research.

Objective:To establish a rapid and precise dose measurement method with EBT4 film and ensure its measurement accuracy to be within the required range through strict operational procedures for the purpose of addressing the two essential issues of poor measurement accuracy and timeliness of EBT film under FLASH conditions.Methods:After storing under different humidity conditions for a certain period of time, the film was exposed to radiation for analyzing the influence of air humidity on the intrinsic performance of EBT film. By means of repeated scanning operations and the film angle rotation, the influences of repeated scanning and film placement angle were analuzed. Parabolic correction method was used to reduce the spatial position influence during the scanning process. By analying the relationship between net optical density (netOD) and absorbed dose through the comparison of three fitting method, the optimal fitting curve was selected. After irradiation of the same batch of films for 5 min and 24 h, the film doses were calibrated and then compared with ionization chamber-measured result. The rapid and precise film dosimetry method was used to measure both the percentage depth dose from X-rays at ultra-high dose rate and the dose distribution at a depth of 2 cm in water.Results:Air humidity had the greatest influence on the intrinsic performance of EBT film (approximately 20%). The average deviation of repeated scans is within 0.5%. The angle at which the film is placed significantly affected the readouts of the film with the maximum influence approximately 70%. The net optical density combined with polynomial fitting can control the fitting residuals of 1-16 Gy within 3%. The change rate of light channels at 5 min already mostly met the requirements of the rapid mode (< 0.5%). Compared with the measurement result obtained using the reference ionization chamber, the deviations of the 5 min or 24 h dose calibration curves were all within 2%.Conclusions:The EBT4 film can be employed as a precise dosimeter to quickly measure the FLASH radiation dose. Rapid and precise FLASH dose measurements can meet the stringent requirements of both preclinical and clinical FLASH research.

ObjectiveTo understand the current situation of anxiety level and traditional Chinese medicine （TCM） nursing needs among residents during the COVID-19 epidemic， and to discuss the relationship between them，so as to provide references for maintaining their mental health. MethodsA total of 560 residents were recruited using convenience sampling method， and the selected individuals completed three questionnaires based on online platform， including self-designed general information questionnaire， Generalized Anxiety Disorder Scale （GAD-7）， and TCM nursing needs questionnaire. Then the correlation between anxiety level and TCM nursing needs was analyzed by Spearman correlation test. ResultsA total of 552 valid questionnaires were collected. The results of GAD-7 showed that the total score was （11.04±3.72）， and average score of each item was （1.58±0.53）. There were 328 cases （59.4%） without anxiety symptoms， 180 cases （32.6%） with mild anxiety， 33 cases （6.0%） with moderate anxiety， and 11 cases （2.0%） with severe anxiety. The analysis of TCM nursing needs questionnaire showed that the total score was （21.59±7.92）， and dominated by the needs of medical knowledge （2.90±1.15） and TCM dietary care （2.82±1.13）. The item score and total score of TCM nursing needs questionnaire of residents during the COVID-19 epidemic were positively correlated with GAD-7 total score （r=0.240~0.331， P<0.01）. ConclusionResidents suffer from different levels of anxiety during the COVID-19 epidemic， and TCM nursing needs is on the rise， indicating that the anxiety level of residents is correlated with the needs of TCM nursing.

Objective To investigate the effects of preeclampsia serum on activity and invasive ability of cultured cytotrophoblasts of first trimester of pregnancy. Methods Cytotrophoblasts of normal 6 to 8-week pregnancy were cultured by tissue explants adherent method,and were incubated with serum of women with normal pregnancy(normal group)and preeclampsia(preeclampsia group),respectively for 24 h.The activity of cytotrophoblasts was examined by CCK-8,invasive ability was determined by Transwell invasion assay,and expression of MMP-2,MMP-9 and PAI-1 mRNA was detected by reverse transcription-polymerase chain reaction(RT-PCR). Results The activity and invasive ability of cytotrophoblasts in preeclampsia group were lower than those in normal group(P<0.05,P<0.01).Compared with normal group,the expression of MMP-2 and MMP-9 mRNA of cytotrophoblasts was significantly lower(P<0.01),and the expression of PAI-1 mRNA was significantly higher(P<0.01).In both groups,the expression of MMP-2 mRNA was negatively related to that of PAI-1 mRNA(r=-0.985,P<0.01;r=-0.933,P<0.05),while there was no correlationship between the expression of MMP-9 mRNA and that of PAI-1 mRNA. Conclusion The preeclampsia serum may affect the invasive ability of cytotrophoblasts by regulating the expression of MMP-2,MMP-9 and PAI-1.