Objective To study the effects of porous prothesis with radial gradient and homogenized structures on stress transmission in the tibia by using finite element method.Methods Based on the reverse engineering technology,the tibial model was constructed,and the bionic trabecular bone structure prosthesis with gradient change of pore edge diameter and the homogeneous bionic trabecular bone structure prosthesis were designed.The Vicon dynamic capture platform was used to obtain the human gait and the axial force of the tibia-femoral joint during flexion,which was imported into ANSYS Workbench as a boundary condition for mechanical performance analysis.Results In the case of proximal defect,the von Mises stress of the bone for prosthesis with radial gradient structure was increased by 3.68 MPa,and that in the case of distal defect was increased by 7.34 MPa.Compared with the homogenized prosthesis,the von Mises stress of the proximal and distal defects was decreased by 171 MPa and 190.4 MPa,respectively.Conclusions The stress of the radial gradient structure prosthesis diffuses from the outside to the middle high porosity area along the prosthesis,which can effectively transfer the tibial plateau load,reduce stress concentration of the prosthesis,improve bone stress and prolong service life of the prosthesis.This study provides a theoretical reference for clinical prosthesis replacement.

Objective To understand the characteristics of occupational noise hazards in key industries in Huizhou City. Methods A total of 247 enterprises from 13 key industries in Huizhou City were selected as the research subjects using the stratified judgment sampling method. The worksite survey of occupational health and workplace noise intensity and spectrum monitoring were conducted at key work sites using "questionnaires and on-site inspections" method. Results The rate of noise intensity exceeding national standards was 53.4% (132/247). The median, 25th and 75th percentile of noise pressure levels in workplaces and worksites were 85.1 (81.2, 91.2)and 82.5 (78.8, 86.3) dB(A), respectively. The high-noise workplaces accounted for 50.0% (479/958). The rate of noise intensity exceeding national standard at work sites was 32.9% (303/921). The sound pressure level of noise at work sites was positively correlated with sound pressure level of noise sources (Spearman correlation coefficient=0.73, P<0.01). The top three high-risk work sites for exceeding national noise standards were grinding, frame nailing, and material cutting, with exceedance rates of 84.6%, 81.3%, and 62.8%, respectively. The frequency characteristics of the top ten high-risk work sites were mainly high-frequency noise. There were significant differences in noise spectrum characteristics among different workpiece materials used in similar types of work sites (all P<0.05), though high-frequency noise remained dominant. Conclusion Noise hazards in workplaces of key industries in Huizhou City are relatively severe. Continuous attention should be given to key work sites with high over-standard rate, such as grinding, frame nailing, and material cutting, and noise control strategies should be developed based on frequency spectrum characteristics.

Objective To study the effects of porous prothesis with radial gradient and homogenized structures on stress transmission in the tibia by using finite element method.Methods Based on the reverse engineering technology,the tibial model was constructed,and the bionic trabecular bone structure prosthesis with gradient change of pore edge diameter and the homogeneous bionic trabecular bone structure prosthesis were designed.The Vicon dynamic capture platform was used to obtain the human gait and the axial force of the tibia-femoral joint during flexion,which was imported into ANSYS Workbench as a boundary condition for mechanical performance analysis.Results In the case of proximal defect,the von Mises stress of the bone for prosthesis with radial gradient structure was increased by 3.68 MPa,and that in the case of distal defect was increased by 7.34 MPa.Compared with the homogenized prosthesis,the von Mises stress of the proximal and distal defects was decreased by 171 MPa and 190.4 MPa,respectively.Conclusions The stress of the radial gradient structure prosthesis diffuses from the outside to the middle high porosity area along the prosthesis,which can effectively transfer the tibial plateau load,reduce stress concentration of the prosthesis,improve bone stress and prolong service life of the prosthesis.This study provides a theoretical reference for clinical prosthesis replacement.

Objective:To explore the radiological damage to cells induced by the delayed particles of 9C-ions for heavy ion therapy, as well as the microdosimetric distribution and biological effects of these particles on a single model of V79 Chinese hamster lung cells. Methods:The Monte Carlo program was employed to simulate the endonuclear absorbed doses of α particles with various energies (3-10 MeV) transported in cells (cell radius RC = 10 μm, nucleus radius RN = 5 μm). Then, the result were compared with the S values ( SN←N, SN←Cy, and SN←CS) derived using the medical internal radiation dose (MIRD) method to demonstrate the feasibility of Monte Carlo simulations. Finally, the energy deposition of the delayed particles of 9C-ions generated at three sites (i.e., on the surface and in the cytoplasm and nucleus of the V79 cell model) during their transport in targets was simulated, and the result ing cell surviving fraction was analyzed. Results:Monte Carlo and MIRD method yielded differences in S values of 1.91%-4.95% for SN←N (nucleus to nucleus), 1.48%-5.11% for SN←Cy (cytoplasm to nucleus), and -1.99% to 0.80% for SN←CS(surface to nucleus), indicating highly consistent S values derived using both method(differences < 6%). When a 9C-ion decayed on the surface of the V79 cell model and the produced secondary particles entered the cell, the average endonuclear absorbed dose was 10 -2 Gy orders of magnitude, with a cell surviving fraction of about 88%. In the case where decay occurred in the cytoplasm, the cell surviving fraction was about 80%. However, when the 9C ion decayed in the nucleus, α particles had short ranges and deposited most of their energy in the cell (mean endonuclear absorbed dose: 0.1 Gy). In this case, severe cell damage was induced, with the cell surviving fraction reducing to about 53%. Conclusions:9C-ions emit secondary charged particles due to decay, among which α particles cause great damage to cells when entering the nucleus and trigger evident biological effects.

Objective:To compare the clinical characteristics of patients with chronic obstructive pulmonary disease (COPD) and cardiovascular diseases between smokers and non-smokers.Methods:In this retrospective cross-sectional study, a total of 735 patients with COPD and comorbid cardiovascular disease who were hospitalized in the Department of Respiratory and Critical Care Medicine of Peking University Third Hospital from January 1, 2017 to August 1, 2022 were enrolled, and were divided into a smoking group (603 cases) and a non-smoking group (132 cases) according to whether or not they had ever smoked. Clinical data, blood counts, C-reactive protein, procalcitonin, echocardiography, comorbidities, hospitalization costs and outcomes were compared between the two groups. Propensity score matching method was used to balance the baseline information between smoking patients and non-smoking patients for further paired analysis. Data were statistically analyzed using t-test, chi-square test, and rank sum test. Results:The percentage of females was significantly higher in patients in the nonsmoking group than in those in the smoking group (65.9% vs 13.6%, P<0.001), and body mass index (BMI) was also significantly higher than in those in the smoking group [(24.4±4.7) vs (23.5±4.4) kg/m 2, P=0.022]. Inflammation indicators neutrophil-to-lymphocyte ratio (NLR) [3.8 (2.2, 8.1) vs 4.9 (2.9, 8.3), P=0.018], C-reactive protein [1.3(0.5, 8.1) vs 7.9(1.1, 35.1) mg/L, P=0.001] were lower in the non-smoking group than in the smoking group. The ratio of early transmitral flow velocity to early mitral annular velocity (E/Em) values were significantly higher in the smoking group than in the nonsmoking group [10(7, 12) vs 8(7, 10) P=0.030]. The cardiovascular disease composition was dominated by hypertension with a lower percentage of combined coronary heart disease in the nonsmoking group than in the smoking group (22.0% vs 35.0%, P=0.034). The two groups were similar in terms of cost during hospitalization and mortality indicators. Conclusions:Among patients with COPD, smokers exhibit higher levels of systemic inflammation, greater cardiac involvement, and an increased risk of ICU admission than non-smokers. Therefore, they require enhanced daily health management and management during hospitalization.

Objective     To identify the potential factors for psychological burdens and to better understand how the patients’ psychological status affect their treatment preferences. Methods     A questionnaire survey was conducted among 996 patients with pulmonary nodules who visited the Thoracic Surgery Clinic of Guangdong Provincial People's Hospital from January to November 2021, including 381 males and 615 females, aged 47.26±11.53 years. A self-administrated questionnaire was used to investigate the sociodemographic and clinical characteristics of the patients, and the Hospital Anxiety and Depression Scale (HADS) was used to evaluate the psychological status of the patients, with a score>7 points of each subscale indicating potential anxiety or depression. Results     Among the 996 patients with pulmonary nodules, the incidence of anxiety was 42.4% and the incidence of depression was 26.4%, while the incidence of both anxiety and depression was 24.7%. There was a significant correlation between anxiety and depression (ρ=0.834, P<0.05). Age, purpose of CT examination, number of pulmonary nodules and symptoms were independent factors for anxiety, while symptoms and number of pulmonary nodules were independent factors for depression (P<0.05). For treatment preferences, there was a statistical difference in educational level, symptoms, nodule size and anxiety level (P<0.05). Conclusion     Anxiety and depression are common in patients with pulmonary nodules. Symptoms are associated with anxiety and depression, which also make an impact on treatment preferences.

Objective    To explore the distribution pattern of respiratory symptoms and relevant factors in patients with pulmonary nodules. Methods    Demographic and clinical information were collected from patients who visited the Thoracic Surgery Outpatient Clinic of Guangdong Provincial People’s Hospital from January 2021 to January 2022. Hospital Anxiety and Depression Scale (HADS) was used to assess their anxiety and depression level. Results    A total of 1 173 patients were enrolled, including 449 males and 724 females, with an average age of 46.94±11.43 years. Among the patients with pulmonary nodules, 37.7% of them had at least one respiratory symptom; 24.4% had cough, 14.0% had expectoration, 1.3% had hemoptysis and 14.9% had chest pain. Old age, male, exposure to second-hand smoking or environmental smoke, hair coloring and history of tuberculosis were major risk factors for respiratory symptoms (P<0.05). Middle age, old age, male, exposure to environmental smoke were major risk factors for cough (P<0.05); old age, smoking, larger maximum nodules diameters, exposure to environmental smoke and history of pneumonia were major risk factors for expectoration (P<0.05); male, multiple nodules, hair coloring, exposure to second-hand smoking and history of tuberculosis were major risk factors for chest pain (P<0.05). Symptomatic patients showed generally higher HADS scores than asymptomatic patients (P<0.001). Conclusion    Cough, expectoration and chest pain are the predominant respiratory symptoms for patients with pulmonary nodules. The presentation of respiratory symptoms increases patients' anxiety and depression.

Objective:To study the effects of gantry acceleration limitations of a linear accelerator (linac) on the dosimetry of volumetric modulated arc therapy (VMAT) plans, machine efficiency, and dose verification result of VMAT plans and to explore the optimal selection of gantry motion models in the Pinnacle treatment planning system.Methods:Ten cases of nasopharyngeal carcinoma, non-small cell lung cancer, sigmoid adenocarcinoma with retroperitoneal lymph node metastasis, and invasive ductal carcinoma of the breast were each selected for this study. Then two models were set up in the Pinnacle v9.10 treatment planning system, namely the one allowing gantry acceleration and the one limiting gantry acceleration. The same field arrangement, optimized target parameters, and optimized weights of VMAT plans were adopted in the two models, in order to analyze the dosimetric variations in targets and organs at risk (OARs) and compare the differences in treatment time and gamma passing rates.Results:The treatment time of the enrolled patients under the model allowing gantry acceleration was significantly lower than that of the patients under the model limiting gantry acceleration was adopted ( t=-6.751, -0.209, -19.523, -28.999; P< 0.05) and decreased by 15.27%, 18.07%, 19.71%, and 28.75%, respectively. Meanwhile, the conformity and uniformity of target areas were affected, while there was no statistical significance in the gamma passing rates in the validation of VMAT plans ( P>0.05). For the cases of nasopharyngeal carcinoma (NPC), the maximum dose to brainstem PRV increased by 1.25%. For the cases of lung cancer, the maximum dose to the spinal cord and lung V20 increased by 1.19% and 1.21%, respectively, while lung V5 decreased by 1.21%. For the cases of sigmoid adenocarcinoma with retroperitoneal lymph node metastasis, the mean doses to bilateral kidneys, livers, small intestine, and colon all increased. For the cases of breast cancer, lung V10 on the opposite side of cancer increased by 1.66% and the mean dose to the lungs on the same side of cancer decreased by 7.45%. Conclusions:The model allowing gantry acceleration allows the treatment time to be significantly shortened and the treatment efficiency improved. Although this model had the shortcomings such as affecting the conformity and uniformity of target areas to a certain extent and increasing the doses to some OARs, clinical requirements for dosimetry were still met. Therefore, it is recommended to use the model allowing gantry acceleration in the Pinnacle planning system.

Objective:To meet the demand of medical system for talents, the training of medical students' competency has become a new direction of medical education. This study aims to evaluate the effectiveness of training quality in medical graduates through the competency scale.Methods:Taking "attitude", "skill" and "knowledge" as the evaluation dimensions, the competency development was divided into four levels of "state", "explain", "apply" and "transfer", and we proposed the competence concept of "A.S.K.-SEAT" and formulated an evaluation scale. Questionnaires and behavior event interviews (BEI) were conducted in medical graduates of Shantou University in 2018. Reliability and validity of the questionnaire were evaluated and current situation of different competency items were analyzed.Results:A total of 155 questionnaires were collected with good reliability and validity, and 15 graduates participated in BEI. A total of 21 A.S.K. competency items (including five basic competency items and two discriminating competency items) and SEAT textual descriptions were finally established.Conclusion:A.S.K.-SEAT scale can provide valid references for the competency evaluation of medical graduates.

Objective To evaluate the safety and efficacy of denosumab in treatment of patients with pelvic giant cell tumor of bone (GCTB) during perioperative period. Methods This is a retrospective observational study. Twenty-three patients diagnosed with pelvic GCTB undergoing perioperative denosumab treatment in Musculoskeletal Tumor Center of Peking University People's Hospital from January 2014 to December 2016 were reviewed. The subjective adverse reactions and mandibular X-ray films were used to assess the drug safety. As for efficacy, imaging findings (including X-ray, CT, magnetic resonance imaging) were reviewed. MSTS-93 scoring system was applied in the postoperative functional assessment. Histological response rate, objective response rate, clinical benefit rate and event-free survival rate were all used to deficit the efficacy of denosumab in the treatment of pelvic GCTB combined with surgery. All the results of postoperative were compared statistically with pelvic GCTB patients who underwent surgery in the same hospital from 1999 to 2009. Results All the patients were firstly diagnosed as classic GCTB except for one case which was malignant pelvic GCTB. All patients received denosumab preoperatively and/or postoperatively, and the average number of medications was 8.43. According to the surgical patterns, patients were divided into intralesional surgery group (13 cases) and wide resection group (10 cases). The follow-up was 5-47 months(mean:27.30 months),recurrence was observed in 2 cases in the intralesional surgery group, none in the wide resection group. After drug administration, 13 cases were partial response, 7 cases were stable disease, the objective response rate was 65.0 % (13/20), and the histologically clearance rate of giant cells was 85.0 % (17/20). No case of osteonecrosis of the jaw was observed in this study, and all laboratory indicators were normal. The average postoperative MSTS-93 score was 26.87. Compared with pelvic GCTB patients who underwent surgical treatment from 1999 to 2009, in the intralesional surgery group, there was no significant difference in the recurrence rate [15.4 % (2/13) vs. 30.8 % (4/13), P = 0.514], but the limb function was significantly increased (P= 0.002). Conclusions Denosumab combined with surgery plays an important role in the multidisciplinary treatment of pelvic GCTB. The neoadjuvant strategy can reduce patient's intraoperative blood loss by shrinking the tumor size which makes the intralesional curettage surgery possible, and also diminishing the recurrence rate. But more attention should be paid to secondary malignant GCTB during the use of denousmab.