After the production of the gradient coil of the magnetic resonance imaging system, electromagnetic field testing is required to verify whether the assembly accuracy meets the electromagnetic field requirements. Since the passive magnetic field B _z satisfies the Laplace ^,s equation and is a harmonic function, and according to the extreme value principle of harmonic function, the maximum or minimum values of B _z can only appear on the boundaries, so the observation points of the magnetic field are generally selected on the surface of the spherical imaging area. For superconducting magnets used for human body magnetic resonance imaging, a spherical area with a center diameter of 40~50 cm is generally selected as the shimming target area. Only the field value of the target area needs to be measured, and the spherical harmonic coefficients obtained after data processing are used to determine the magnetic field performance of the gradient coil. There are many testing principles and methods for electromagnetic fields, so there is no unified way and method in the field of commercial applications. This article is based on the Gauss-Legendre numerical integration, measures and analyzes the magnetic field performance of gradient coils by building a data acquisition system, and this article applies numerical analysis methods to calculate the spherical harmonic coefficients of the magnetic field using discrete test data, providing a feasible method for the production and testing of gradient coils.
Magnetic Resonance Imaging/methods* ; Magnetic Fields ; Electromagnetic Fields ; Equipment Design

Objective:To analyze and compare the interfractional setup errors between two body posi-tioning fixation methods(lithotomy position with carbon fiber full-body fixation frame vs.conventional carbon fiber body fixation frame combined with thermoplastic membrane)in radical radiotherapy for pros-tate cancer,and to calculate the clinical target volume(CTV)to planning target volume(PTV)margin(MPTV)for both methods to optimize immobilization techniques and radiotherapy workflows.Methods:A retrospective analysis was conducted on 37 consecutive patients who underwent radical prostate radio-therapy at Peking University First Hospital between August 2021 and March 2023.The patients were di-vided into two groups based on the immobilization method:Group A(18 patients,450 CBCT image sets)used a carbon fiber whole-body fixator in the lithotomy position,while Group B(19 patients,461 CBCT image sets)used a conventional carbon fiber fixator combined with a thermoplastic mask.All the patients underwent daily cone-beam computed tomography(CBCT)image guidance.Bone registration combined with manual registration was used to obtain the setup error data in the left-right(X),cranio-caudal(Y)and anterior-posterior(Z)directions.The positioning errors of the two groups were compared by using the independent sample t-test,the Mann-Whitney U test and the chi-square test.The average positioning error,systematic positioning error(Σ)and random positioning error(δ)were calculated,and the CTV-PTV extension distance was calculated by using the(MPTV=2.5Σ+0.7δ).Results:The analysis of the setup errors in the three-dimensional direction showed significant differences between the two groups(all P＜0.01).Specifically,the median(quartile)absolute values of the errors in the X,Y,and Z di-rections of group A were[0.40(0.20,0.70)cm,0.50(0.30,0.80)cm,and 0.35(0.20,0.60)cm],respectively.In group B,the corresponding values were significantly reduced to[0.20(0.10,0.40)cm,0.40(0.20,0.70)cm and 0.20(0.10,0.40)cm].The results of Mann-Whitney U test showed that the differences in each direction were highly statistically significant(X:z=-6.86;Y:z=-2.76;Z:z=-5.71).The cumulative distribution ratio of the setup error displacement within 0.5 cm in the X,Y,and Z directions in group A and group B were 297(66.0％)and 408(88.5％)(P＜0.01),250(55.6％)and 285(61.8％)(P=0.055),308(68.4％)and 391(84.8％)(P＜0.01),re-spectively.The CTV-PTV margins in three directions were X 0.66 cm in group A and 0.35 cm in group B;Y0.67 cm and 0.45 cm;Z 0.54 cm and 0.42 cm.Conclusion:Conventional carbon fiber human body fixator combined with thermoplastic film can significantly reduce the setup error.However,the car-bon fiber whole-body fixator in the lithotomy position demonstrated larger setup errors in the X,Y,and Z directions compared with the conventional fixator combined with a thermoplastic mask,indicating the need for further workflow optimization.Given that the lithotomy position is essential for transperineal ultrasound-guided techniques,further research and improvements are required to achieve higher positioning accuracy.

Objective:To analyze and compare the interfractional setup errors between two body posi-tioning fixation methods(lithotomy position with carbon fiber full-body fixation frame vs.conventional carbon fiber body fixation frame combined with thermoplastic membrane)in radical radiotherapy for pros-tate cancer,and to calculate the clinical target volume(CTV)to planning target volume(PTV)margin(MPTV)for both methods to optimize immobilization techniques and radiotherapy workflows.Methods:A retrospective analysis was conducted on 37 consecutive patients who underwent radical prostate radio-therapy at Peking University First Hospital between August 2021 and March 2023.The patients were di-vided into two groups based on the immobilization method:Group A(18 patients,450 CBCT image sets)used a carbon fiber whole-body fixator in the lithotomy position,while Group B(19 patients,461 CBCT image sets)used a conventional carbon fiber fixator combined with a thermoplastic mask.All the patients underwent daily cone-beam computed tomography(CBCT)image guidance.Bone registration combined with manual registration was used to obtain the setup error data in the left-right(X),cranio-caudal(Y)and anterior-posterior(Z)directions.The positioning errors of the two groups were compared by using the independent sample t-test,the Mann-Whitney U test and the chi-square test.The average positioning error,systematic positioning error(Σ)and random positioning error(δ)were calculated,and the CTV-PTV extension distance was calculated by using the(MPTV=2.5Σ+0.7δ).Results:The analysis of the setup errors in the three-dimensional direction showed significant differences between the two groups(all P＜0.01).Specifically,the median(quartile)absolute values of the errors in the X,Y,and Z di-rections of group A were[0.40(0.20,0.70)cm,0.50(0.30,0.80)cm,and 0.35(0.20,0.60)cm],respectively.In group B,the corresponding values were significantly reduced to[0.20(0.10,0.40)cm,0.40(0.20,0.70)cm and 0.20(0.10,0.40)cm].The results of Mann-Whitney U test showed that the differences in each direction were highly statistically significant(X:z=-6.86;Y:z=-2.76;Z:z=-5.71).The cumulative distribution ratio of the setup error displacement within 0.5 cm in the X,Y,and Z directions in group A and group B were 297(66.0％)and 408(88.5％)(P＜0.01),250(55.6％)and 285(61.8％)(P=0.055),308(68.4％)and 391(84.8％)(P＜0.01),re-spectively.The CTV-PTV margins in three directions were X 0.66 cm in group A and 0.35 cm in group B;Y0.67 cm and 0.45 cm;Z 0.54 cm and 0.42 cm.Conclusion:Conventional carbon fiber human body fixator combined with thermoplastic film can significantly reduce the setup error.However,the car-bon fiber whole-body fixator in the lithotomy position demonstrated larger setup errors in the X,Y,and Z directions compared with the conventional fixator combined with a thermoplastic mask,indicating the need for further workflow optimization.Given that the lithotomy position is essential for transperineal ultrasound-guided techniques,further research and improvements are required to achieve higher positioning accuracy.

Objective:To investigate the effect of long non-coding RNA (lncRNA) human histocompatibility leukocyte antigen complex P5 (HCP5) on the neuronal injury induced by oxygen glucose deprivation/reoxygenation (OGD/R), and to analyze its potential mechanism.Methods:SH-SY5Y cells were divided into control group (CON group, normal medium culture), model group (Model group, OGD/R), interference control group (si-NC group, OGD/R after HCP5 small interfering RNA negative control (si-NC)), HCP5 interference group (si-HCP5 group, OGD/R after HCP5 small interfering RNA (si-HCP5)), HCP5 interference+ inhibitor control group (si-HCP5+ anti-NC group, OGD/R after transfection of si-HCP5, miR-525-5p inhibitor negative control (anti-NC)), HCP5 interference+ miR-525-5p inhibitor group (si-HCP5+ anti-miR-525-5p group, OGD/R after transfection of si-HCP5, miR-525-5p inhibitor). qRT-PCR was used to detect the expression of lncRNA HCP5 and miR-525-5p in cells.The activity of SH-SY5Y cells was detected by MTT.The level of reactive oxygen species (ROS) in the cells was detected by fluorescent probe of dichlorofluorescein diacetate (DCFH-DA). The apoptosis of SH-SY5Y cells was detected by flow cytometry.Western blot was used to detect the expression of BTG2, Bcl-2 related X protein (Bax), B lymphocyte tumor 2 (Bcl-2) and cleaved caspase-3 protein.SPSS 25.0 software was used to analyze the data, and one-way ANOVA was used for comparison between multiple groups, and SNK- q test was used for further comparison between two groups. Results:There were statistically significant differences in lncRNA HCP5, miR-525-5p RNA levels and BTG2 protein expression levels among the 6 groups ( F=28.853, 59.241, 13.731, all P<0.001). Compared with the CON group, the Model group had higher level of lncRNA HCP5, lower level of miR-525-5p, and higher level of BTG2 protein (all P<0.05). Compared with the Model group, the si-HCP5 group had lower level of lncRNA HCP5, higher level of miR-525-5p, and lower level of BTG2 protein (all P<0.05). Compared with the si-HCP5+ anti-NC group, the si-HCP5+ anti-miR-525-5p group had higher level of lncRNA HCP5, lower level of miR-525-5p, and higher level of BTG2 protein (all P<0.05). There were statistically significant differences in cell activity and ROS levels among the six groups of cells ( F=16.180, 59.950, both P<0.001). The cell activity of the Model group was lower than that of the CON group (0.33±0.12, 0.63±0.11) ( P<0.05), and the ROS level was higher than that of the CON group (224.62±23.27, 100.00±0.00) ( P<0.05). The cell activity of the si-HCP5+ anti-miR-525-5p group was lower than that of the si-HCP5+ anti-NC group (0.38±0.08, 0.58±0.08) ( P<0.05), and the ROS level was higher than that of the si-HCP5+ anti-NC group (207.83±19.39, 135.27±14.36) ( P<0.05). There were statistically significant differences in the apoptosis rate and expression levels of apoptotic proteins Bcl-2, Bax, and cleared Caspase-3 among the six groups of cells ( F=27.994, 29.660, 45.000, 52.983, all P<0.001). There were no statistically significant difference in Bax, Bcl-2, cleared Caspase-3 protein levels, and apoptosis rate in SH-SY5Y cells between the Model group and the si-NC group, as well as between the si-HCP5 group and the si-HCP5+ anti-NC group (all P>0.05). Compared with the CON group, the apoptosis rate, levels of Bax and cleared Casase-3 protein in the Model group were significantly upregulated (all P<0.05), while the Bcl-2 protein level was significantly downregulated ( P<0.05). Compared with the Model group and si-NC group, the si-HCP5 group showed significant downregulation of cell apoptosis rate and levels of Bax and cleared Caspase-3 protein (all P<0.05), while the Bcl-2 protein level was upregulated ( P<0.05). Compared with the si-HCP5 group and si-HCP5+ anti-NC group, the si-HCP5+ anti-miR-525-5p group showed significant upregulation of cell apoptosis rate and levels of Bax and cleared Caspase-3 protein levels (all P<0.05), and significant downregulation of Bcl-2 protein levels ( P<0.05). Conclusion:lncRNA HCP5 may inhibit the expression of BTG2 by targeting up-regulation of miR-525-5p, thus leading to apoptosis of nerve cells in OGD/R models.

Oral and maxillofacial space infections (OMSI) are common diseases of the facial region involving fascial spaces. Recently, OMSI shows trends of multi drug-resistance, severe symptoms, and increased mortality. OMSI treatment principles need to be updated to improve the cure rate. Based on the clinical experiences of Chinese experts and with the incorporation of international counterparts′ expertise, the principles of preoperative checklist, interpretation of examination results, empirical medication principles, surgical treatment principles, postoperative drainage principles, prevention strategies of wisdom teeth pericoronitis-related OMSI, blood glucose management, physiotherapy principles, Ludwig′s angina treatment and perioperative care were systematically summarized and an expert consensus on the diagnosis and treatment of OMSI was reached. The consensus aims to provide criteria for the diagnosis and treatment of OMSI in China so as to improve the level of OMSI treatment.

Objective? To explore the effects of enhanced recovery after surgery based on nutritional support in perioperative nursing of elderly patients with hip fracture and joint replacement. Methods? From January 2015 to June 2017, we selected 278 elderly hip fracture patients with nutritional risk (NRS 2002≥3) by convenience sampling. All of the patients were divided into observation group (n=132) and control group (n=146) with the method of envelope. Observation group accepted nutritional support and brought it into enhanced recovery nursing process. Control group applied routine perioperative nursing without standardized nutritional support. We compared the albumin and loss of hemoglobin at the second day after surgery, the score of activity of daily living (ADL), time of getting out from bed for the first time, hospital stay as well as complications of patients between two groups. Results? The albumin at the second day after surgery and score of ADL of patients in observation group were (29.16±1.33) g/dl and (63.90±5.47) respectively higher than those in control group;the loss of hemoglobin after surgery, time of getting out from bed for the first time, hospital stay in observation group were (1.34±0.30) g/dl, (1.56±0.20)d, (7.08±2.23)d respectively lower than those in control group;the differences were all statistical (t=-3.089, -14.881, -13.640, -15.279, -8.480;P＜0.05). The incidence of complications of observation group was 9.09% lower than that of control group (19.18%) with statistical difference (χ2=3.877, P＜0.05). Conclusions? Enhanced recovery nursing based on nutritional support can shorten the hospital stay in elderly patients with hip fracture, promote postoperative rehabilitation after hip joint replacement and improve clinical outcomes of patients.

Objective To investigate the prevalence of nutritional risk and undernutrition of geriatric patients with hip fracture in the department of orthopaedics and analyze the relationship between nutritional risk scores and clinical outcomes.Methods In this prospective cohort study,the baseline demographic data of 235 elderly patients with hip fracture in the department of orthopaedics of Ningbo First Hospital were consecutively recorded from November 2013 to December 2015.The prevalence of nutritional risk and undernutrition,infectious complications,and length of hospital stay were also recorded.The infectious complications and length of hospital stay in patients in different age groups(60-69 years,70-79 years,and ≥80 years)and those with different nutritional risks(<3 points,3-4 points,and ≥5 points)were analyzed.Results All patients without PN EN support during hospitalized durations.The incidence of nutritional risk was 62.98％in 235 elderly patients with hip fracture,twenty patients were undernutritioned by multi-item standard based on Nutritional Risk Screening 2002 nutrition disorder score,and 15 patients were undernutritioned by one-item standard with body mass index.Hip arthroplasty patients had significantly higher nutritional risk than those who had undergone internal fixation(74.04％vs.54.20％,P=0.002).Patients with comorbidities had significantly higher nutritional risk than patients without comorbidities(71.56％vs.55.56％,P=0.011).There were significant differences in infectious complications(2.30％vs.3.91％vs.50.00％)and length of hospital stay[(6.35±0.87)d vs.(8.12±1.13)d vs.(10.85±1.52)d,(8.66±2.06)d vs.(10.45±2.43)d vs.(13.25 ±3.65)d] among patients with different nutritional risks(<3 points,3-4 points,and ≥5 points)(P=0.000).Conclusions Elderly patients with hip fracture has relatatively high nutritional risk.These patients tend to have more complications and longer hospital stay.

Objective To evaluate the technique and clinical effect of arthroscopic treatment of anterior cruciate ligament tibial eminence avulsion fracture with suture bridge fixation technique. Methods From May 2013 to July 2015, 18 patients with anterior cruciate ligament tibial eminence avulsion fracture were treated with arthroscopic re﹣duction and fixation by suture bridge technique. There were 12 males and 6 females with an average age of 29.8 years old (range, 9~45 years). The right knees were involved in 10 cases and left knees in 8 cases. The injury caus﹣es included traffic accident injury in 10 cases, sports injury in 5 cases and other reasons in 3 cases. 2 patients had old fracture, the others had fresh fracture. The results of Lachman and anterior drawer test were both positive. The International Knee Documentation Committee (IKDC) subject score was (53.8 ± 4.2). Based on Meyers-Mckeaver classification, there were 5 cases in typeⅡ, 10 cases in type Ⅲ and 3 cases in type Ⅳ. Results The operation time was 50~80 minutes (mean, 60.5 minutes), X-ray showed satisfactory fracture reduction after surgery. Primary healing of incision were obtained with no infection, all 18 patients were followed up for 6 ~ 31 months (mean, 18.6 months). The results of Lachman and anterior drawer test were both negative in 17 cases, the result was negative for anterior drawer test and was weakly positive for Lachamn test in 1 case. The IKDC subject score were significantly improved to (95.2 ± 3.8) at last follow-up (P< 0.05). Conclusion It could achieve early restoration of knee joint function to treat the anterior cruciate ligament tibial eminence avulsion fracture with suture bridge fixation technique because of satisfactory reduction, reliable fixation, minor trauma, and quick recovery.

Objective To investigate the current status of perioperative nutritional risk and nutritional intake in aged patients with hip fracture, so as to provide references for standard nutritional support. Methods A prospective cohort study was designed. 235 patients with hip fracture admitted in the Orthopedics Department of Ningbo First Hospital from November 2013 to December 2015 were selected and investigated by nutritional risk screening 2002 ( NRS-2002 ) , to assess the nutritional risk of patients with hip fracture and collect their nutritional intake situation. Results The nutritional risk of 235 patients with hip fracture was 63. 40%, which was higher than that of patients without hip fracture (χ2=37.445,P<0.05), and it was also higher than that of patients with other kinds of fracture ( P<0. 05 ) . Single factor analysis showed that, the perioperative nutritional risk of aged patients with hip fracture was influenced by surgical procedures (χ2 =9. 093,P<0.05) . 235 aged patients with hip fracture were given daily foods in the perioperative period, and the intake of protein and calories were lower than the standard recommended in guideline. Conclusions The nutritional risk in aged patients with hip fracture is high, and the nutritional support was not enough, which should be paid attention by clinical medical workers.

Objective To understand the risk factors of the elderly in community of Haining city in patients with Alzheimer's disease.Methods Take the elderly Chang street Haining city selected cluster sampling method 7 437 ≥60 years as the research subjects,by using a self-designed questionnaire Alzheimer's disease causes and clinical dementia rating scale,understanding the factors that may affect Alzheimer's disease and aggravating factors,and the data of multi factor regression analysis.Results Multivariate Logistic regression analysis showed that women (Wald x2 =19.96,P ＜ 0.01),aged (Wald x2 =96.01,P ＜ 0.01),widowed (Wald x2 =5.09,P ＜ 0.05),smoking/drinking (Wald x2 =47.77,P ＜ 0.01),living alone (Wald x2 =16.14,P ＜ 0.01),depression (Wald x2 =12.05,P ＜ 0.01) were the risk factors of Alzheimer's disease; Rural (Wald x2 =458.11,P ＜ 0.01) ; Lowculture (Wald x2 =121.39,P ＜0.01) were protective factors for Alzheimer's disease.According to the clinical dementia rating scale of disease severity assessment and pathogenesis of polytomous Logistic regression,the results showed that the elderly (Wald x2 =50.37,P ＜ 0.01),lowculture (Wald x2 =30.39,P ＜ 0.01),widowed (Wald x2 =5.20,P ＜ 0.05),living alone (Wald x2 =16.50,P ＜ 0.01),somatic diseases (Wald x2 =16.58,P ＜ 0.01) and large maternal age (Wald x2 =10.53,P ＜ 0.01) were risk factors for disease.Conclusion Age,widowed,solitude are common risk factors of Alzheimer's disease and aggravating factors,should be combined with risk factors for chronic disease management actively take measures to prevent and delay the occurrence,the development of Alzheimer's disease.