Objective:To explore the dosimetry optimization strategy based on filter thickness and shape selection for the bulb superficial X-ray radiotherapy unit.Methods:Monte Carlo code TOPAS was used to model tubular equipment, and the dose distribution from six X-ray energies (50-150 kV) and five conventional aluminum filters (0.5-3.0 mm) with different thickness were simulated in the water model. The percentage depth dose (PDD) curve along the central axis, the center-axis profile dose at different depths, and the lateral dose distribution were analyzed. The dose distribution of three different designs of aluminum filters (conventional cylindrical, conical and oblique cylindrical filters) was compared to evaluate the effect of dosimetric optimization of different filter shapes.Results:Under the same energy, increasing the thickness of the filter can optimize the superficial skin dose, and the optimization effect of depth dose uniformity can be increased by 26% at a depth of 5.5 mm at 70 kV energy. The raised, flat and inclined dose distribution modes can be achieved by using conventional cylindrical, conical and inclined aluminum filters.Conclusions:By selecting the appropriate X-ray energy and filter thickness, an ideal dose distribution matching the tumor depth can be achieved. The application of personalized filters is also of great significance for diverse target areas.

Objective:To investigate the application of the conjugate gradient (CG) algorithm to treatment plan optimization for intensity-modulated brachytherapy (IMBT).Methods:The general Monte Carlo software TOPAS was utilized to simulate the 192Ir source of IMBT, and the unit dose contribution matrix was calculated. An objective function was established using the weighted least squares method and was solved using the CG algorithm to achieve optimized IMBT treatment plans. The optimization was validated using five clinical cervical cancer cases under modulation width 60°. The dose distributions of IMBT treatment plans under 45°, 60°, 90°, 120°, and 180° modulation widths were compared using the Wilcoxon test to determine the optimal IMBT treatment plan for cervical cancer treatment. Results:The CG algorithm successfully optimized IMBT treatment plans under modulation width 60° for five cases within 22.2 s on average. On the premise of sufficient target dose coverage, the average D2 cm 3 values of the bladder and rectum in IMBT treatment plans were 3.66 and 1.97 Gy, respectively, representing reductions of 0.54 and 0.69 Gy compared to traditional brachytherapy plans. For the five modulation widths, the D90% values of all IMBT treatment plans reached 6 Gy, without statistically significant differences ( P > 0.05). The average D2 cm 3 values of the bladder in IMBT treatment plans were significantly lower than those in the traditional brachytherapy plans( P<0.05), with modulation width 60° associated with the greatest reduction of 0.61 Gy. In contrast, the average D2 cm 3 values of the rectum under 45°, 60°, and 90° modulation widths decreased by 0.63, 0.54, and 0.45 Gy, respectively, compared to traditional plans, with statistically significant differences( P<0.05). Conclusions:The CG method enables rapid achievement of optimized IMBT treatment plans that meet clinical requirements, and modulation width 60° contributes to valid dosimetric optimization. This study can serve as a guide for the clinical implementation of IMBT.

Transmission X-ray tubes are relatively new devices characterized by portability,suitability for miniaturization,and low requirements for shielding,making them ideal radiation sources for kilovoltage X-ray therapy.However,their application in radiotherapy remains underexplored.An electron target model of a transmission X-ray tube is developed using the Monte Carlo toolkit TOPAS 3.8.1.The study investigates the effect of tungsten target thickness on X-ray output efficiency,finding that a tube voltage of 50 kV and a tungsten thickness of 1.4 μm yields the highest emission efficiency.Based on the energy spectrum at this optimal efficiency,polynomial fitting approach is applied to determine the corresponding aluminum filter thickness for mean energies ranging from 20 keV to 35 keV,achieving a mean fitting error of 0.91%.Next,the study simulates dose deposition in a water phantom for spectra with different mean energies and various source-to-surface distances,and plots percent-depth-dose curves,relative normalized dose-depth curves,and relative normalized dose histograms under each treatment condition.Finally,the simulated results are compared with experimental data from the intraoperative radiotherapy system Intrabeam and the superficial X-ray therapy unit SRT-100,obtaining average relative errors of 3.71%and 4.38%,respectively.These findings provide a theoretical foundation for further optimization of transmission X-ray tubes in kilovoltage radiotherapy.

OBJECTIVE To evaluate the efficacy， safety and cost-effectiveness of apixaban in the prevention and treatment of cancer-associated venous thromboembolism （CA-VTE）， and provide evidence-based reference for clinical treatment. METHODS Retrieved from PubMed， the Cochrane Library， CNKI， Wanfang， VIP database and other websites of health technology assessment （HTA）， systematic review/meta-analysis， pharmacoeconomic studies and HTA reports of apixaban in the prevention and treatment of CA-VTE were collected. After data extraction and quality evaluation， the results of the included study were analyzed descriptively. RESULTS A total of 23 literatures were included， involving 16 systematic review/meta-analysis and 7 pharmacoeconomic studies. In terms of efficacy， compared with placebo， prophylactic use of apixaban could significantly reduce the incidence of venous thromboembolism （VTE） in outpatient adult cancer patients receiving chemotherapy （P＜0.05）. Compared with low-molecular weight heparin （LMWH）， rivaroxaban and warfarin， there were no statistically significant differences in the incidence of VTE for apixaban （P＞0.05）； nevertheless， apixaban was ranked as the most preferable choice. For the treatment of patients with CA-VTE， compared with warfarin， apixaban could significantly reduce the recurrence rate of VTE （P＜0.05）. While compared with patients treated with LMWH， rivaroxaban， edoxaban and dabigatran， there were no statistically significant differences in the recurrence rates of VTE， deep venous thrombosis and pulmonary embolism among patients using apixaban （P＞0.05）. In terms of safety， compared with placebo， prophylactic use of apixaban showed a higher occurrence of major bleeding in outpatient adult cancer patients receiving chemotherapy （P＜0.05）， while compared withpatients treated with LMWH， rivaroxaban， and warfarin， there were no statistically significant differences in the incidence of major bleeding among patients using apixaban （P＞0.05）； despite this， apixaban was ranked as the most favorable option. For the treatment of patients with CA-VTE， compared with dalteparin， the incidence of major bleeding and all-cause mortality of apixaban were similar （P＞0.05）， while the incidence of clinically relevant non-major bleeding （CRNMB） was higher （P＜0.05）. Compared with edoxaban， the incidence of major bleeding of apixaban was reduced significantly （P＜0.05）， while there was no significant difference in the incidence of CRNMB， the incidence of clinically relevant bleeding and all-cause mortality （P＞0.05）. Compared with rivaroxaban， warfarin and dabigatran， there were no significant differences in the incidence of major bleeding， the incidence of CRNMB， the incidence of clinically relevant bleeding and all-cause mortality （P＞0.05）. In terms of cost-effectiveness， the researches in China showed that apixaban was cost-effective in preventing CA-VTE； foreign studies showed that apixaban was cost-effective in preventing and treating CA-VTE. CONCLUSIONS Apixaban is effective， safe and cost- effective in the prevention and treatment of CA-VTE.

Objective:To explore the dosimetry optimization strategy based on filter thickness and shape selection for the bulb superficial X-ray radiotherapy unit.Methods:Monte Carlo code TOPAS was used to model tubular equipment, and the dose distribution from six X-ray energies (50-150 kV) and five conventional aluminum filters (0.5-3.0 mm) with different thickness were simulated in the water model. The percentage depth dose (PDD) curve along the central axis, the center-axis profile dose at different depths, and the lateral dose distribution were analyzed. The dose distribution of three different designs of aluminum filters (conventional cylindrical, conical and oblique cylindrical filters) was compared to evaluate the effect of dosimetric optimization of different filter shapes.Results:Under the same energy, increasing the thickness of the filter can optimize the superficial skin dose, and the optimization effect of depth dose uniformity can be increased by 26% at a depth of 5.5 mm at 70 kV energy. The raised, flat and inclined dose distribution modes can be achieved by using conventional cylindrical, conical and inclined aluminum filters.Conclusions:By selecting the appropriate X-ray energy and filter thickness, an ideal dose distribution matching the tumor depth can be achieved. The application of personalized filters is also of great significance for diverse target areas.

Objective:To investigate the application of the conjugate gradient (CG) algorithm to treatment plan optimization for intensity-modulated brachytherapy (IMBT).Methods:The general Monte Carlo software TOPAS was utilized to simulate the 192Ir source of IMBT, and the unit dose contribution matrix was calculated. An objective function was established using the weighted least squares method and was solved using the CG algorithm to achieve optimized IMBT treatment plans. The optimization was validated using five clinical cervical cancer cases under modulation width 60°. The dose distributions of IMBT treatment plans under 45°, 60°, 90°, 120°, and 180° modulation widths were compared using the Wilcoxon test to determine the optimal IMBT treatment plan for cervical cancer treatment. Results:The CG algorithm successfully optimized IMBT treatment plans under modulation width 60° for five cases within 22.2 s on average. On the premise of sufficient target dose coverage, the average D2 cm 3 values of the bladder and rectum in IMBT treatment plans were 3.66 and 1.97 Gy, respectively, representing reductions of 0.54 and 0.69 Gy compared to traditional brachytherapy plans. For the five modulation widths, the D90% values of all IMBT treatment plans reached 6 Gy, without statistically significant differences ( P > 0.05). The average D2 cm 3 values of the bladder in IMBT treatment plans were significantly lower than those in the traditional brachytherapy plans( P<0.05), with modulation width 60° associated with the greatest reduction of 0.61 Gy. In contrast, the average D2 cm 3 values of the rectum under 45°, 60°, and 90° modulation widths decreased by 0.63, 0.54, and 0.45 Gy, respectively, compared to traditional plans, with statistically significant differences( P<0.05). Conclusions:The CG method enables rapid achievement of optimized IMBT treatment plans that meet clinical requirements, and modulation width 60° contributes to valid dosimetric optimization. This study can serve as a guide for the clinical implementation of IMBT.

Transmission X-ray tubes are relatively new devices characterized by portability,suitability for miniaturization,and low requirements for shielding,making them ideal radiation sources for kilovoltage X-ray therapy.However,their application in radiotherapy remains underexplored.An electron target model of a transmission X-ray tube is developed using the Monte Carlo toolkit TOPAS 3.8.1.The study investigates the effect of tungsten target thickness on X-ray output efficiency,finding that a tube voltage of 50 kV and a tungsten thickness of 1.4 μm yields the highest emission efficiency.Based on the energy spectrum at this optimal efficiency,polynomial fitting approach is applied to determine the corresponding aluminum filter thickness for mean energies ranging from 20 keV to 35 keV,achieving a mean fitting error of 0.91%.Next,the study simulates dose deposition in a water phantom for spectra with different mean energies and various source-to-surface distances,and plots percent-depth-dose curves,relative normalized dose-depth curves,and relative normalized dose histograms under each treatment condition.Finally,the simulated results are compared with experimental data from the intraoperative radiotherapy system Intrabeam and the superficial X-ray therapy unit SRT-100,obtaining average relative errors of 3.71%and 4.38%,respectively.These findings provide a theoretical foundation for further optimization of transmission X-ray tubes in kilovoltage radiotherapy.

Objective:To compare the curative effect of local anesthesia Lichtenstein, modified Kugel and general anesthetic transabdominal preperitoneal(TAPP) hemioplasty in the treatment of primary unilateral inguinal hernia in elderly patients.Methods:Six hundred and twenty-one patients with unilateral primary inguinal hernia admitted at Second Hospital of Tianjin Medical University from January 2021 to December 2023 were randomly divided into 3 groups before operation: Lichtenstein group, Modified-Kugel group, TAPP group,207 patients in each group. The clinical data were compared.Results:The average operation time of the Lichtenstein and modified Kugel hernia repair groups was significantly shorter than that of TAPP group ( P<0.01), and the hospitalization cost was also significantly lower than that of TAPP group. The postoperative pain score, time spent in the ground and hospital stay in TAPP group were significantly lower than those in Lichtenstein and modified Kugel groups ( P<0.05). There were no serious complications in the 3 groups. Conclusions:Three kinds of hernia repair are all safe and effective in the treatment of elderly patients with unilateral primary inguinal hernia. TAPP has lighter postoperative pain and quicker recovery. Lichtenstein and Modified-Kugel hernia repair under local anesthesia are suitable for those who cannot tolerate general anesthesia.

Objective:To compare the curative effect of local anesthesia Lichtenstein, modified Kugel and general anesthetic transabdominal preperitoneal(TAPP) hemioplasty in the treatment of primary unilateral inguinal hernia in elderly patients.Methods:Six hundred and twenty-one patients with unilateral primary inguinal hernia admitted at Second Hospital of Tianjin Medical University from January 2021 to December 2023 were randomly divided into 3 groups before operation: Lichtenstein group, Modified-Kugel group, TAPP group,207 patients in each group. The clinical data were compared.Results:The average operation time of the Lichtenstein and modified Kugel hernia repair groups was significantly shorter than that of TAPP group ( P<0.01), and the hospitalization cost was also significantly lower than that of TAPP group. The postoperative pain score, time spent in the ground and hospital stay in TAPP group were significantly lower than those in Lichtenstein and modified Kugel groups ( P<0.05). There were no serious complications in the 3 groups. Conclusions:Three kinds of hernia repair are all safe and effective in the treatment of elderly patients with unilateral primary inguinal hernia. TAPP has lighter postoperative pain and quicker recovery. Lichtenstein and Modified-Kugel hernia repair under local anesthesia are suitable for those who cannot tolerate general anesthesia.

Objective To determine the time point when porcine pancreatic elastase(PPE)induced abdominal aortic aneurysm(AAA)reaches the regression phase in mice and observe the histological characteristics of AAA in regression phase.Methods AAAs were induced by transient intraluminal infusion of PPE in C57BL/6J mice.The diameters of the mouse abdominal aortas were measured before PPE infusion and sacrifice time,day 14 for AAA progression phase or day 56 for regression phase after PPE infusion,respectively.The histological characteristics of the aneurysm lesion site on day 14 and day 56 after surgery were compared and analyzed.Results The diameters of the abdominal aortas were significantly increased in both day 14 and day 56 after PPE infusion groups(diameter growth rate 147％and 155％,respectively)as compared to the baseline diameters.In the day 14 group,the infused aortas showed typical AAA characteristics,such as elastin break/degradation,medial smooth muscle cells depletion,and inflammatory cell diffused infiltration.In the day 56 group after PPE infusion,although the artery diameter did not change significantly as compared to the day 14 group,histology showed that elastin was partially repaired,new smooth muscle cells were added to the damaged aorta media,the infiltrated inflammatory cells were significantly subsided,and the adventitia neovascularization was reduced,showing a significant feature of the disease regression phase.Conclusion In the PPE-induced mouse AAA model,day 56 after surgery is an appropriate time point for observing aneurysm regression,and the histological characteristics of the regression are obvious.