BACKGROUND: Composite resin functions as a practical resin restoration material with beautiful outlook, modifying its mechanical properties has become a hot spot in research.OBJECTIVE: To prepare resin specimens with two kinds of inlay curing machines: CERAMAGE and TESCERA, and to compare the mechanical properties of these specimens.METHODS: The resin specimens supporting two machines were cross-matched with these machines and then divided into four groups: Group A was Tescrea resin prepared with TESCERA machine; group B was Tescrea resin prepared with CERAMAGE machine; group C was Ceramage resin prepared with CERAMAGE machine; group D was Ceramage resin prepared with TESCERA machine. The standard specimens were determined for compressive strength, hardness and flexural strength.RESULTS AND CONCLUSION: The compressive strength and hardness in group A were higher than those in other three groups,and group B exhibited higher compressive strength and hardness than groups C and D (P < 0.05). The flexural strength in groups C and D was higher than that in groups A and B (P < 0.05), there was no significant difference between groups C and D, neither betweens group A and B. The experimental findings indicate that TESCERA inlay machine and Tescera resin achieve the optimal mechanical properties.

Objective To investigate the positioning errors of head and neck during intensity-modulated radiation therapy of nasopharyngeal carcinoma.Methods Nineteen patients with middle-advanced nasopharyngeal carcinoma (T2-4N1-3M0), treated by intensity-modulated radiation therapy, underwent repeated CT during their 6-week treatment course.All the patients were immobilized by head-neck-shoulder thermoplastic mask.We evaluated their anatomic landmark coordinated in a total of 66 repeated CT data sets and respective x, y, z shifts relative to their position in the planning CT.ResultsThe positioning error of the neck was 2.44 mm±2.24 mm,2.05 mm±1.42 mm,1.83 mm±1.53 mm in x, y, z respectively.And that of the head was 1.05 mm±0.87 mm,1.23 mm±1.05 mm,1.17 mm±1.55 mm respectively.The positioning error between neck and head have respectively statistical difference (t=-6.58,-5.28,-3.42,P=0.000,0.000,0.001).The system error of the neck was 2.33,1.67 and 1.56 higher than that of the head, respectively in left-right, vertical and head-foot directions;and the random error of neck was 2.57,1.34 and 0.99 higher than that of head respectively.Conclusions In the process of the intensity-modulated radiation therapy of nasopharyngeal carcinoma, with the immobilization by head-neck-shoulder thermoplastic mask, the positioning error of neck is higher than that of head.

Objective To investigate an appropriate megavoltage computed tomography ( MVCT ) protocol to guide helical tomotherapy ( HT) for multiple metastases. Methods According to the location of target volume, 48 patients with multiple metastases undergoing HT were divided into head/chest group ( n=15), head/pelvis group (n=15), and chest/pelvis group (n=18). Each target volume received MVCT scans during the treatment. The obtained MVCT images were registered to CT images and the setup errors were recorded. The CTV?PTV margins were calculated. Comparison was made by paired t test. Results In the head/chest group, there was no significant difference in the setup error in x?axis between the head and chest (-0.15±1?25 vs. -0.21±2?34, P=0?71), while the head had significantly smaller setup errors in y?and z?axis than the chest (0.73±1?22 vs. 1.56±2?54, P=0?00;0.93±1?44 vs. 2.65±1?88, P=0?00). In the head/pelvis group, the head had significantly smaller setup errors in x?, y?, and z?axis than the pelvis (-0.16±1?31 vs. -1.29±3?72, P=0?00;0.81±1?34 vs. 3.20±3?90, P=0?00;1.24±1?75 vs. 5.49±2?80, P=0?00) . In the chest/pelvis group, there were no significant differences in setup errors in x?or y?axis between the chest and pelvis (-0.25± 2?90 vs. -0.22± 3?65, P=0?06;0.35± 3?60 vs. 0.38± 3?78, P=0?87), while the chest had a significantly smaller setup error in z?axis than the pelvis (1.95±2?81 vs. 3.35± 3?05, P=0?00) . In the three groups, the CTV?PTV margins of lower target volume were reduced in three dimensions after the correction of upper target volume, in which y?axis showed the largest reduction of CTV?PTV margins (5?13 vs. 4?01;9?17 vs. 8?30;8?52 vs. 7?13). Conclusions The setup error of individual target volume should not be used for correction of the overall setup error in HT for multiple metastases with isolated target volume. An MVCT protocol that provides image?based guidance for multiple target volumes is recommended.

Objective To investigate the impact of high intra-abdominal pressure on intracranial pressure in patients with traumatic brain injury and discuss the clinical significance of abdominal decom-pression. Methods Intra-abdominal pressure and intracranial pressure of 15 patients with abdominal trauma and brain injury were observed to discuss changes of intracranial pressure after abdominal decom-pression. Results After abdominal decompression, all patients got lower intracranial pressure, with decrease of (15.2±3.6) mm Hg. Conclusion Intra-abdominal pressure does affect intracranial pres-sure for patients with abdominal trauma and brain injury. Abdominal decompression may be effective for high intracranial pressure.

Objective To investigate and analyze clinical obstetrics and gynecology clinicians' mastery of basic skills, and then find the way to help clinicians master basic clinical skills. Methods A self-designed questionnaire survey was conducted among 310 clinicians working in 1-3 grade hospital from Chongqing, Sichuan, Guizhou, Yunnan provinces anonymously by spot field investigation and letter-investigations from February 1, 2015 and to March 31, 2015. The data were analyzed by descriptive analysis, using SPSS 19.0 software package for rank sum test analysis. Result Among 310 valid questionnaires, 31.6% (98) clinicians considered having inadequate clinical skills, 26% (81) average and 42.3%(131) expert. All the basic skills obtained had a relationship with the number of operations, working years and professional title. Most of the basic clinical skills were from working in hospitals 85% (270), journal 82% (254), academic conference 58% (174); 94.2% (293) willing to participate in training classes like clinical teaching and training in moulds. Conclusion The gynecology and obstet-rics basic clinical skills have a great relationship with basic skills training. Providing opportunities for the basic clinical skill trainings, academic conferences, in-service education and establishing regional medical source sharing platform can enhance their clinical skills.

Objective To evaluate the clinical effect of femoral neck fracture fixed with 7.5mm QWIX screws and to find out risk factors for avascular necrosis of the femoral head postoperatively.Methods From January 2009 and March 2013, 53 patients underwent closed or open reduction of femoral neck fracture with 7.5mm QWIX screws.Healing process of fracture, complications of internal fixation, Harris hip score and avascular necrosis of the femoral head were followed up.The data reviewed were age, gender, injury patterns, fracture type, preoperative waiting time, reduction ways, reduction condition, and others.Unilateral and multivariate Logistic analysis were applied to identify factors for avascular necrosis of the femoral head.Results All patients were followed up for 2-5 years (mean, 3.4 years).There was no non-union at follow-up, and all the screws were in the original site without loosening, cut-out or penetration.Mean Harris score was 91.2 points (range, 68 to 100 points) 2 years after operation, including 42 excellent, 6 good, 1 fair and 4 poor results with the excellent-good rate of 91％.Four patients (8％) had avascular necrosis 12 to 15 months after operation.With Logistic regression analysis, fracture anatomic type was identified as the only factor for avascular necrosis of the femoral head.Conclusions The 7.5 mm QWIX fixation screw provides rigid fixation, high healing rate and low incidence of avascular necrosis of the femoral head, appearing to be a good hardware to repair femoral neck fracture.Avascular necrosis of the femoral head is associated with the anatomic type of femoral neck fracture after operation.

Purpose: Simulating calculation the dose distribution of the total body irradiation (TBI) with three dimension treatment planning system(3D-TPS ). Materials and Methods: For TBI, the source skin distance(SSD) is 380 cm, field size is 40 cm × 40cm, and collimator angle is 45°. The percent dose depth (PDD) and onset axis ratio (OAR) of the linac accelerator is measured with the big water phantom self-made. In the same radiation condition, the PDD and OAR of water which is simulated calculation with the 3D-TPS is compared with the measurement results to confirm whether the 3D-TPS can calculate the TBI dose distribution. The dose distribution of the human phantom is calculated with 3D-TPS, which is compared and confirmed with the film and TLD measurements. Results: The maximum error of PDD and OAR in the water phantom between the measurements and calculations of 3D-TPS are 3% and 6%. The calculation results of the 3D-TPS is according with the measurement results of the film and TLD approximately. Conclusions: 3D-TPS could simulate calculation the dose distribution for TBI accurately. It is possible to improve more uniform dose for TBI with corresponding compensator for specific patient.

Objective:To investigate the clinical feasibility of the Unity radiotherapy system guided by magnetic resonance imaging.Methods:Twenty-four patients were enrolled and received a total of 384 fractions of treatment at Unity system. According to the treatment site, all patients were divided into head-neck, abdomen-thorax, pelvic, spine and limb groups. The patients were set-up without external laser. And then, the time required at different stages in online treatment process and the registration error of each fraction were separately calculated. The geometric deformations of MR images were weekly measured by using MR geometric deformation phantom. At last, the Arccheck was used to perform the dose verification of reference plan, online plan and offline plan.Results:The mean duration of radiotherapy in the five groups were 29.1, 27.6, 26.6, 25.6 and 32.0 min, respectively. The set-up errors in the left-right, superior-inferior and anterior-posterior direction in the five groups were: head-neck group (0.08±0.06 cm, 0.16±0.13 cm, 0.08±0.05 cm), abdomen-thorax group (0.23±0.18 cm, 0.50±0.47 cm, 0.12±0.1 cm), pelvic group (0.25±0.19 cm, 0.32±0.25 cm, 0.11±0.09 cm), spine group (0.46±0.38 cm, 0.26±0.26 cm, 0.13±0.07 cm) and limb group (0.33±0.30 cm, 0.34±0.23 cm, 0.08±0.06 cm), respectively. In the central region, the geometric deformation of MR was less than 0.3 mm, and that of the sphere with a diameter of 500 mm was less than 2.1 mm. The meanγ pass rate of the reference plan, online plan and offline plan were 97.92%, 97.84% and 94.58%, respectively.Conclusions:MR-guided radiotherapy has great potential for clinical application, whereas the process of Unity system is relatively complex. The synergy of different departments has a great impact on the treatment, which needs further optimization.

Objective To develop a MOSAIQ Integration PlatformCHN (MIP) based on the workflow of radiotherapy (RT) and to meet the actual requirements in China and the special needs for the radiotherapy department.Methods MIP used C/S (client-server) structure mode running on the local network in the hospital and its database was based on the Treatment Planning System (TPS) and MOSAIQ database.Five network servers,as the core hardware,supplied data storage and network service based on cloud services.The core software was developed based on Microsoft Visual Studio Platform using C# network programming language.The MIP server could simultaneously offer network service for about 200 workstations,including entry,query,statistics,and print of data.Results MIP had 15 core function modules,such as Notice,Appointment,Billing,Document Management (application/execution),and System Management,which almost covered the whole workflow of radiotherapy.Up to June 2016,the recorded data in the MIP were as follows:13546 patients,13533 plan application forms,15475 RT records,14656 RT summaries,567048 billing records,and 506612 workload records.Conclusions The MIP based on the RT workflow has been successfully developed and used in clinical practice.It is an important part of radiotherapy information system construction with the advantages of intuitive operation,real-time performance,data security,and stable operation.It is digital,paperless,user-friendly,and convenient for the retrieval and statistics of data as well as information sharing and department management,and can significantly improve the efficiency of the department.More functions can be added or modified to enhance its potentials in research and clinical practice.

Objective To compare the positioning accuracy between personalized polyurethane foam with wing boards and negative pressure vacuum bag in radiotherapy for lung cancer using kilovoltage cone beam computed tomography(CBCT). Methods Thirty-nine patients with lung cancer who received chest radiotherapy in our hospital from 2015 to 2016 were enrolled as subjects. In those patients, 20 were immobilized by negative pressure vacuum bags(VB group)and the others by personalized polyurethane foam with wing boards(PF group).CBCT images were acquired weekly and registered with planning CT images. Setup errors in the left-right, superior-inferior, and anterior-posterior directions, three-dimensional(3D) displacement vector,and setup time were recorded. The margin of the planning target volume(PTV)was calculated using the Van Herk formula(2.5∑+0.7σ). Between-group comparison was made by paired t test. Results The PF group had a significant smaller setup error in the y-direction than the VB group (2.54±1.79 vs.3.19±2.14 mm,P=0.03),while there were no significant differences in setup errors in the x-or z-direction between the two groups(1.80± 1.48 vs. 1.90± 1.41 mm, P=0.46;2.14± 1.75 vs. 2.25± 1.75 mm,P=0.35). There were no significant differences in rotational setup errors in the Rx-,Ry-,or Rz-direction between the two groups(1.15°±0.76°vs. 1.15°±0.85°, P=0.50;0.71°±0.60°vs. 0.72°±0.43°, P=0.45;0.62°±0.54° vs. 0.46°±0.30°,P=0.06). The PTV margins in the x?,y?,and z?directions were expanded by 5.56, 8.57, and 7.02 mm, respectively, in the PF group, and by 5.62, 9.27, and 7.23 mm,respectively,in the VB group. The proportion of patients with 3D displacement vectors larger than 5 mm was 40% in the PF group and 45% in the VB group.Conclusions For patients undergoing radiotherapy for lung cancer,personalized polyurethane foam with wing boards can,to a certain extent,reduce the setup error in the superior-inferior direction and PTV margin expansion.[Key words] Lung neoplasms/radiotherapy; Polyurethane foam; Vacuum bag; Setup errors;Margin