Objective:To investigate the factors affecting the accuracy of electronic portal imaging device (EPID)-based in vivo dose verification in radiotherapy for patients with lung and esophageal cancers, and to recommend the workflow and specifications for the application of the in vivo dose verification. Methods:This study randomly selected 32 patients who received radiotherapy for esophageal and lung cancers at the Department of Radiation Oncology, Jinhua Municipal Central Hospital from May to August 2022, including 14 lung cancer cases and 18 esophageal cancer cases. Using a uRT-linac 506c linear accelerator, these patients were treated according to the dynamic intensity-modulated radiotherapy (dIMRT) and EPID-based In vivo dose verification ( In vivo EPID) plans developed with the uRT-TPOIS planning system. The In vivo dose verification performed during the treatment included 238 fractions of In vivo EPID and 80 fractions of image-guided radiotherapy (IGRT) for the lung cancer cases, as well as 414 fractions of In vivo EPID and 105 fractions of IGRT for the esophageal cancer cases. The 2D γ passing rate for each irradiation field was obtained according to the set threshold value. Furthermore, fractioned irradiation fields with γ-passing rates below the threshold value were analyzed, and primary factors decreasing the γ-passing rate were further analyzed by combining the online CT images and 3D reconstruction-derived dose. Results:For lung and esophageal cancers, the mean γ-passing rates were 95.1% ± 5.7% and 96.5% ± 4.5%, respectively at 3 mm/5%; 91.5% ± 8.4% and 92.2% ± 4.9%, respectively at 3 mm/3%, and 79.1% ± 14.7% and 83.7% ± 8.2%, respectively at 2 mm/2%, indicating no statistically significant differences between two cancers ( P > 0.05). The average γ passing rate for beam orientations near 0°/180° (Group A) was higher than those near 90°/270° (Group B) 3 mm/5%: Z = -25.4, P < 0.05; 3 mm/3%: Z = -26.8, P < 0.05). The IGRT correction of setup errors significantly improved the γ passing rates (96.3% ± 5.1% and 96.4% ± 4.9%, respectively at 3 mm/5%, Z = -5.50, P < 0.05; 92.3% ± 8.0% and 91.3% ± 7.7%, respectively at 3 mm/3%, Z = -9.54, P < 0.05). The results of In vivo dose verification were affected by changes in the volumes and motion of tumors and normal tissues, radiotherapy positioning, and adequacy of pre-treatment preparation. Conclusions:EPID-based In vivo dose verification during radiotherapy can avoid incorrect irradiation. However, it is necessary to standardize the workflow of the EPID-based In vivo dose verification to avoid the decrease in the γ passing rate caused by artificial factors.

Objective:To investigate the adhesion of polydopamine-modified collagen membrane composites to cartilage tissues and the effect on chondrocyte proliferation, and further explore the possibility of their application in autologous chondrocyte transplantation.Methods:Porous collagen membranes were prepared, and the polydopamine-modified collagen membrane composites were constructed by the adsorption method. The physical and chemical properties and structural characteristics of the membranes, such as thermal stability, thermal properties, porous structure, and surface element composition, were characterized by infrared spectroscopy, thermogravimetric analysis, differential thermal analysis, scanning electron microscopy, and X-ray photoelectron spectroscopy, respectively. The adhesion between the polydopamine-modified collagen membrane and fresh cartilage tissue was tested by a mechanical testing machine. The effects of the membranes on the adhesion and proliferation of rabbit chondrocytes were investigated by in vitro cell culture.Results:The structure and surface element composition of the membranes altered with the increase in the adsorption time of polydopamine, and the capacity of polydopamine increased with the increase in the adsorption time. The thermal stability and thermal properties of collagen membrane materials were not significantly affected by the adsorption of polydopamine. The adhesion of the membrane to cartilage tissue increased with the increase in the amount of absorbed polydopamine. The membranes showed a time-dependent promoting effect on the proliferation of the chondrocytes.Conclusions:The polydopamine-modified collagen membrane has potential application in articular cartilage repair, but more research is required to optimize the membrane before it is used in articular cartilage repair.

Objective:To observe the effect of project-based learning (PBL) in the clinical teaching of radiation physics.Methods:Thirty-two residents specializing in radiotherapy were included in the study. In the experimental group ( n=16), PBL was adopted, while traditional clinical teaching method was employed in the control group ( n=16). After the rotation, the assessment was conducted, as well as a questionnaire survey was performed, including five aspects: overall satisfaction, understanding of radiation physics knowledge, learning motivation, learning burden, and learning efficiency. Results:The assessment score in the experimental group was 86.31±5.41, which was higher than 75.28±5.91 in the control group, and the difference was statistically significant. Residents in the experimental group were satisfied with the effect of PBL.Conclusion:Compared with the traditional teaching method, PBL can improve the learning motivation, efficiency, and performance of radiotherapy residents, which is highly recognized by the residents.

Matching is a standard method for selecting research objects regarding the observational research, which controls confounding factors and improves statistical efficiency. However, its role in controlling confounding is not consistent in different observational studies. Matching can eliminate the confounding bias of matching variables in cohort studies, but checking on itself cannot eliminate confounding bias in case-control studies. In matched case-control studies, researchers may not accurately judge whether the variable is a confounder. Sometimes the variables that are not confounders are mistakenly matched. In that case, it will result in overmatching, which will lead to the decline of statistical efficiency or the introduction of unavoidable bias or increase of workload. If the real confounding factors are omitted, it will cause confounding bias. Therefore, researchers should consider what kind of matching variable selection criteria should be formulated. A directed acyclic graph is a visual graphic language that can show the complicated causality among different epidemiological research designs. This article analyzes the role of Matching in different observational research designs from the perspective of the directed acyclic graph, formulates the selection criteria for matching variables in matched case-control studies, and provides some reference suggestions for future epidemiological research design.

Epidemiological analysis describes and compares the characteristics of a certain number of people to make causal inferences. The formation of the study population is always the first step. In this paper, we first define the concepts of cross-sections at both individual level and population level and introduce the three assumptions needed in the measurements in observational studies, i. e. the true values of the attributes are stable with time, the attribute variables are independent and the individuals are independent during the measuring process. We also determine that the causal inference research should be unified based on the time of the occurrence or beginning of a postulated cause, or exposure, should be in. Then, based on the dual roles of the population cross-section with causal thinking, we propose that research designs can be classified into two types with different characteristics: history reconstruction research and future exploration research. Finally, we briefly analyze the research design framework and the relationship between estimated effects and different designs. The discussion of the formation of a study population from the perspective of causal thinking can make a foundation for the classification of causal inference research design with appropriate effect parameters, which needs to be further studied.

Objective:To analyze and compare the dosimetric differences based on volumetric-modulated arc therapy (VMAT), fixed field intensity-modulated radiotherapy (F_IMRT), and electron irradiation combined with VMAT (E&VMAT) in radiotherapy for breast cancer after modified mastectomy, aiming to provide reference for clinical selection of treatment plan.Methods:Ten patients with the left breast cancer who received radiotherapy after modified mastectomy were randomly selected. The target areas included chest wall and supraclavicular region, and the prescribed dose was 43.5 Gy in 15 fractions (2.9 Gy/F). Based on the Pinnacle 3 planning system, the VMAT, F_IMRT and E&VMAT plans (electron beam for chest wall, VMAT for supraclavicular area) were designed for each patient. The conformity and homogeneity of the target areas, the dose of organs at risk and treatment time were compared. Results:The VMAT plan could improve the dose distribution of the target areas. The conformity index and homogeneity index of the target dose were significantly better than those of the F_IMRT and E&VMAT plans (all P<0.05). The average dose, V 30Gy, V 20Gy, V 10Gy of the left lung in the VMAT plan were significantly better than those in the F_IMRT and E&VMAT plans (all P<0.05). The V 5Gy of the left lung in the VMAT plan was significantly better than that in the F_IMRT plan ( P<0.05). There was no statistical difference in the V 5Gy of the left lung between the VMAT and E&VMAT plans ( P>0.05). The heart, right breast and right lung of the VMAT plan could meet the clinical dose limit requirements. The treatment time of the VMAT, F_IMRT and E&VMAT plans was (326±27) s, (1 082±169) s, and (562±48) s, respectively. Conclusions:Compared with the F_IMRT and E&VMAT plans, the VMAT plan has better quality and shorter treatment time. VMAT plan has higher value in clinical application compared with the F_IMRT and E&VMAT plans.

Due to the flaws inherited in synchronicity, statistical association and survivor bias on variables under measurement, a common 'consensus’ has been reached on "cross-sectiional studies (CSS) can lead to failure on causal inference". In this paper, under both causal thinking and diagram, the real and measured cross-sections are clearly defined that these two concepts only exist theoretically. In real CSS research, the temporal orders of measured variables are all non-synchronic, equivalent to the assumption that measurement variables are independent to each other, or there is no differentiated classification bias. Similar to cumulative case-control or historical cohort studies, both exposure and outcome that exist or occur before their measurements in cross-sectional studies, are actions of historical reconstruction or doing 'Archaeology’. One of the common preconditions for causal inference in such studies is that: there must be a causal relation between the measured variables and their historical counterparts. The measured variables are all agents of their corresponding real counterparts, and the temporal orders are not that important in causal inference. It is necessary to better understand the analytic role of the CSS.

In causal inference, the concept of temporality (or directionality) has not been fully clarified. Starting from causal thinking, this paper divides the time axis in nature into three time domains and two time points by the occurrence timings of both a real cause and a real effect. This has anchored that causal inference can only be realized in the third domain. The measured temporalities can be divided into five types: cross-first-to-third-domain longitudinal (or experimental temporalities), cross-second-to-third-domain longitudinal, within-domain longitudinal, within-domain reversely longitudinal, and within-domain transversal (or observational temporalities). This new classification encompasses all measurement strategies, either for first or multiple measurements, or timely and delayed measurements. Except that the actual measurement for the cause occurs either before its occurrence (only in experiment) or within the second domain, all other measurements are similar to the act of historical reconstruction or "archaeology" , where the importance of measured temporalities may be inferior to the accuracy of the measurements. From the point of view that research design should integrate bias design, this new classification for measured temporalities based on the time axis in Nature, which has a clear meaning and helps to judge the possible biases in the observation methods, provides a basis for correct causal inferences.

Objective:To investigate the efficacy of tacrolimus combined with irbesartan in treating female patients with lupus nephritis and its effect on serum levels of high mobility protein B1(HMGB1) and receptor for advanced glycation products(RAGE).Methods:Sixty female patients with lupus nephritis admitted to the First People's Hospital of Wenling from January 2018 to May 2019 were included and divided into control group and observation group according to the random number table method, with 30 cases in each group.The control group received tacrolimus.The observation group was treated with irbesartan on the basis of the control group.After 6 months of continuous treatment, the renal function, scores of lupus nephritis activity index(SLE-DAI) and chronic disease index(SLE-CI), the efficacy, and serum levels of HMGB1 and RAGE were compared between the two groups.Results:Compared with the control group, the serum levels of creatinine(SCr)[(76.46±9.09)μmol/L], urea nitrogen(BUN)[(6.71±0.88)mmol/L], 24h urinary protein quantification[(1.38±0.21)g/24h], scores of SLE-DAI[(9.09±1.41)points] and SLE-CI[(1.17±0.17)points] were significantly reduced in the observation group after treatment, and the plasma albumin(Alb)[(35.08±5.11)g/L] and estimated glomerular filtration rate(eGFR)[(57.79±6.94)mL/min] were significantly increased (all P<0.01). The total effective rates of the observation group and the control group were 90.00% and 63.33%, respectively, and the difference between the two groups was statistically significant(χ 2=4.565, P<0.05). Compared with the control group, the serum levels of HMGB1[(52.31±7.13)μg/L] and RAGE[(1.11±0.18)μg/L] in the observation group were significantly reduced after treatment(all P<0.01). Conclusion:The efficacy of tacrolimus combined with irbesartan in the treatment of female patients with lupus nephritis is significant, and it can inhibit serum levels of HMGB1 and RAGE.

Objective:To explore the enhancement effect of different concentrations of contrast media on blood vessels and hollow organs in CT enterography.Methods:Sixty patients with CT enterography were enrolled from January to August 2019 at Shanghai Ninth People's Hospital, and were prospectively randomly divided into three groups (group A: 90 ml 400 mg/ml contrast media, group B: 90 ml 350 mg/ml contrast media, and group C: 79 ml 400 mg/ml contrast media). Evaluation parameters included CT value, signal noise ratio (SNR) and contrast noise ratio (CNR) of main abdominal vessels (abdominal aorta, superior and inferior mesenteric atery, jejunal artery, ileum artery, superior and inferior mesenteric vein), jejunum, ileum and inflammatory bowel disease. The overall image quality and direct jejunum ileum artery quality scores were evaluated. One-way ANOVA was used to compare the parameters among the three groups.Results:There was no statistical difference in CT value, SNR and CNR of each measurement index among the three groups in plain scan ( P>0.05). The CT value, SNR and CNR of abdominal aorta, superior mesenteric artery, inferior mesenteric artery, jejunal artery and ileal artery in group A and C were higher than those in group B in arterial phase ( P<0.05), but there was no significant difference between group A and group C ( P>0.05). The CT value, SNR and CNR of superior mesenteric vein, inferior mesenteric vein, normal jejunum, ileum and inflammatory lesions in group A were higher than those in group B and C in venous phase ( P<0.05), but there was no significant difference between group B and group C ( P>0.05). The overall image quality scores of group A, B and C were (3.8±0.7), (3.4±0.6), (3.4±0.6), respectively, with no significant difference ( F=3.075, P=0.054). The direct jejunum ileum artery scores of the three groups were (3.5±0.5), (3.1±0.5), (3.4±0.5), respectively, the difference was statistically significant ( F=3.684, P=0.031). Conclusion:At the same injection rate and scanning parameters, contrast media at 400 mg/ml can provide better vessel and hollow organ enhancement.