Magnesium stents have gained increasing interest as an ideal stent of future intervention. In order to study the deformation behavior of magnesium alloy stents in the interventional treatment, the finite element method was used to analysis the effects of different crimp and expansion dimensions on the mechanical properties (maximum stress, radial recoil rate, longitudinal shortening rate and radial strength). The results showed that crimping and expanding have a minimal influence on the stent radial strength. When the expansion size is same, the maximum equivalent stress and recoil rate decrease with the crimp size. When the crimp size is same, in contrast with the radial recoil rate, the maximum equivalent stress and longitudinal shortening rate increase with the expansion size. In addition the paper verified the radial strength-radial displacement curve obtained by FEM. Results are basically consistent, indicating the finite element method can efficiently provide researchers with reliable, high-quality design.
Alloys ; Finite Element Analysis ; Magnesium ; Stents

Objective To investigate the expression and significance of serum NSE,HCY and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in the patients with acute cerebral infarction(ACI).Methods One hundred cases of ACI treated in the neurology department of this hospital from March 2013 to December 2015 were selected as the cerebral infarction group,and contemporaneous 100 persons undergoing healthy physical examination were selected as the control group.The cerebral infarction group were re-divided into three groups according to the infarction volume,the infarction area ＞ 10 cm3 as the large volume infarction group (L),5-10 cm3 as the middle volume infarction group (M) and ＜5 cm3 as the small volume infarction group (S).The levels of serum NSE,HCY and 8-OHdG were compared between the cerebral infarction group and the control group,and among the group L,M and S.The Pearson correlation test was adopted to conduct the correlation analysis between HCY,8-OHdG and NSE with the cerebral infarction volume,neural function deficit,and prognosis.Results The levels of Hcy,8-OHdG and NSE in the observation group were higher than those in the control group,the difference was statistically significant(P＜0.05);the levels of Hcy,8-OHdG and NSE in the group L were higher than those in the group M and S,the difference was statistically significant(P＜0.05);the Hcy,8-OHdG and NSE levels were positively correlated with the cerebral infarction volume and neurological deficit,and negatively correlated with the prognosis.Conclusion Serum NSE,HCY and 8-OH-dG levels are increased in the patients with ACI,moreover with the infarct volume increase,which are gradually elevated.Therefore serum NSE,HCY and 8-OHdG can be used to assess the severity and prognosis in ACI patients.

Objective To compare the dosimetric differences between intracavitary brachytherapy in combination with interstitial brachytherapy or not for locally advanced cervical cancer.Methods From May 2016 to March 2017,35 patients with locally advanced cervical cancer treated with combined external beams and intracavitary/interstitial brachytherapy were selected in this study.The prescription of intensity-modulated radiation therapy was:46.8-50.4 Gy/26-28 fractions,1.8 Gy/fraction.The prescription for combined intracavitary/interstitial brachytherapy was 7 Gy/fraction × 4,once per week.Each patient was first implanted with a three tube applicator for brachytherapy,and the CT images were acquired for treatment planning.The three tube applicator was removed before a uterine tube and needles were implanted,thereafter planning images were acquired again.Dose to the targets and organs at risk were evaluated respectively for the two groups.Results A total of 212 brachytherapy plans were developed,including 106 intracavitary and 106 endoluminal combined interstitial plans.The target dose in endoluminal combined interstitial brachytherapy was significantly higher than that of intracavitary treatment alone,where D90 of the high-risk clinical target volume (CTV) and moderate CTV were both significantly increased (t =-6.01,-2.73,P ＜ 0.05).The D2 cm3 of the bladder,rectum and sigmoid colon were significantly reduced (t=3.07,4.52,2.91,P＜0.05).Conclusions The application of the endoluminal combined interstitial brachytherapy for locally advanced cervical cancer can significantly increase the target dose,and reduce the dose to organs at risk such as the bladder,rectum and sigmoid colon.

Objective:To investigate the dosimetry advantage of 3D-printed minimally invasive guided template used in local advanced cervical cancer intracavitary combined with interstitial radiotherapy.Methods:A total of 68 cases with locally advanced cervical cancer who were admitted to Hebei Cangzhou Hospital of intergrated traditional Chinese medicine and western medicine from May 2016 to August 2019 were selected. All the patients had eccentric tumor or large tumor (tumor diameter >5 cm) after radiotherapy. Intensity modulated radiotherapy was used for external radiotherapy, and intracavitary combined with interstitial radiotherapy was used for brachytherapy. The prescription dose of high-risk clinical target volume (HR-CTV) is 6 Gy/fraction, once a week, five fractions in total. Sixty-eight patients were randomly divided into two groups, 35 cases in the template group who received minimally invasive 3D printing guided template assisted intrauterine tube implantation and insertion needle implantation, and 33 patients in the free implantation group who received free hand intrauterine tube implantation and insertion needle implantation. The position and depth of the insertion needle were adjusted by CT-guidance, and the final CT image was transmitted to the Oncentra Brachy treatment planning system, then the target volume and organs at risk were delineated for planning and treatment.Results:A total of 340 brchytherapy plans were made, including 175 in the template group and 165 in the free implantation group. The D90 values of the HR-CTV and intermediate-risk clinical target volume (IR-CTV) in the template group were increased ( t=3.63, 2.45, P<0.05), and D2 cm3 values (dose of 2 cm 3 of organ at risk) of bladder, rectum and sigmoid colon were significantly decreased ( t=-2.81, -2.54, -2.33, P<0.05). At the same time, the average CT scanning times of each treatment in the template group was (1.78±0.53) times, the average duration of each treatment was (11.35±3.98) min, and the average number of needles used in each implant treatment was (5.21±1.37). The result of free implantation group was higher than that of the template group. The differences were statistically significant ( t=-2.26, -4.53, -3.21, P<0.05). Conclusions:For localized advanced cervical cancer patients with eccentric or large tumors, the 3D printed minimally invasive guided template for intracavitary and interstitial implantation has obvious dosimetry advantages, and the operation is simpler and the duration is shorter.

Objective: To investigate the application of 3D-printed minimally-invasiveguided template in the treatment of recurrent cer-vical cancer after surgery, assisting interstitial brachytherapy. Methods: From July 2017 to April 2018, a total of 10 patients admitted to Cangzhou Hospital of Integrated Traditional Chinese and Western Medicine in Hebei province with recurrent cervical cancer after radi-cal surgery underwent the 3D-printed customized template-assisted interstitial brachytherapy. According to the specific conditions of patients, different vaginal localization templates were selected for CT simulation localization. The main guidance needle space distribu-tion was designed, and 3D minimally-invasive guidance templates were printed. Then, needles were inserted according to the main guide channel of the template commissioned by medical photosensitive resin. The high-risk clinical target volume (HR-CTV) of 6 Gy/fraction was administered (4 to 6 fractions). Results: Overall, 10 patients were treated with implantation for a total of 52 times. Treat-ment with average scanning CT number for each brachytherapy was (1.58±0.70) times. The average elapsed time for each brachythera-py implant treatment, from plug implant to inserting planting needle satisfactorily with the location of the tumor, was (10.88±2.94) minutes. The mean number of metal needles used was (5.69±1.91) in each brachytherapy. The mean D90 value for high-risk clinical tar-get volume (HR-CTV) was (6.41±0.29) Gy. The cumulative D2cm3 values for the bladder, rectum, and sigmoid colon were (4.75±0.37) Gy, (3.93±0.26) Gy, and (4.33±0.24) Gy, respectively. After 3 months of treatment, the efficacy was evaluated in 8 cases with CR and 2 cas-es with PR. Conclusions: The technology of 3D-printed minimally-invasive guided template shows the advantage of accurate location and superior repeatability in the application of interstitial brachytherapy in treating recurrent cervical cancer after operation, which in-volves less time and insertion needles. The patients had minor aches and few complications. The tumor shrank significantly, which indi-cated a bright future of the technology's clinical application.

Objective: To evaluate the efficacy and safety of bevacizumab in the treatment of radiation brain necrosis, and to provide guidance for rational clinical application. Methods: A retrospective analysis was made of 14 patients with radiation brain necrosis who had failed to receive mannitol and hormone treatment or had been treated for the first time. All the patients were divided into two groups according to different treatment regimens (5.0 mg/kg repeated every 14 d and 7.5 mg/kg repeated every 21 d). The changes of enhanced lesions in MRI T1W1 phase and edema in T2W1 phase were compared separately in the two groups. The clinical symptoms, changes of KPS score and adverse drug reactions were recorded. Results: Totally 14 patients completed at least two cycles of treatment. After two cycles of treatment, the KPS scores of both groups were improved. The KPS scores of 5.0 mg/kg group were increased by 31.66 points on average compared with those before treatment. The KPS scores of 7.5 mg/kg group were increased by 27.50 points on average compared with those before treatment. The volume of CRN lesions were decreased(46.0±9.4)%(t=6.57, P<0.05) and the volume of edema lesions decreased(68.9±8.9)%(t=3.32, P<0.05) in 5.0 mg/kg group. In 7.5 mg/kg group, these two parameters were reduced by(53.9±10.7)%(t=7.89, P<0.05 and (77.1±14.3)%(t=4.22, P<0.05), respectively. There was no significant difference in the reduction of the mean volume of CRN lesions and the volume of edema area between the two groups (P>0.05). In this study, the incidence of adverse events in the 5.0 mg/kg group was similar to that in the 7.5 mg/kg group, with no significant difference(P>0.05). Conclusions Bevacizumab can significantly improve the clinical symptoms and quality of life of patients with radiation brain necrosis. The safety of 5.0 mg/kg treatment regimen repeated every 14 d is similar to that of 7.5 mg/kg treatment regimen repeated every 21 d, which can be used for reference in the treatment of CRN.