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 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.

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.

Acute Kidney Injury (AKI) is a common and severe complication after cardiac surgery. The pathogenesis of cardiac surgery-associated AKI (CSA-AKI) is complex, and it is associated with increased patient mortality and poor renal prognosis. To identify high-risk patients as early as possible, numerous clinical studies have explored perioperative risk factors and developed a variety of biomarkers with good diagnostic capabilities. Currently, multiple prediction models for AKI after cardiac surgery have been developed internationally; however, there is no effective treatment for CSA-AKI. Therefore, implementing reasonable and comprehensive preventive strategies is crucial. In addition, the clinical application of some interventions is controversial, which means more research and exploration are needed to make more informed decisions regarding the prevention and treatment of CSA-AKI.

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.

Acute kidney injury (AKI) usually requires renal replacement therapy (RRT). Common RRT modes include peritoneal dialysis, continuous renal replacement therapy, intermittent hemodialysis and continuous low-efficiency hemodialysis. In clinical practice, there is still controversy over how to select the appropriate RRT mode for AKI patients and when initiating RRT is more beneficial for AKI patients. This article summarizes previous studies on the impact of RRT mode and initiation timing on the prognosis of AKI patients, with the aim of providing assistance for clinical decision-making.

Acute kidney injury (AKI) usually requires renal replacement therapy (RRT). Common RRT modes include peritoneal dialysis, continuous renal replacement therapy, intermittent hemodialysis and continuous low-efficiency hemodialysis. In clinical practice, there is still controversy over how to select the appropriate RRT mode for AKI patients and when initiating RRT is more beneficial for AKI patients. This article summarizes previous studies on the impact of RRT mode and initiation timing on the prognosis of AKI patients, with the aim of providing assistance for clinical decision-making.

Acute Kidney Injury (AKI) is a common and severe complication after cardiac surgery. The pathogenesis of cardiac surgery-associated AKI (CSA-AKI) is complex, and it is associated with increased patient mortality and poor renal prognosis. To identify high-risk patients as early as possible, numerous clinical studies have explored perioperative risk factors and developed a variety of biomarkers with good diagnostic capabilities. Currently, multiple prediction models for AKI after cardiac surgery have been developed internationally; however, there is no effective treatment for CSA-AKI. Therefore, implementing reasonable and comprehensive preventive strategies is crucial. In addition, the clinical application of some interventions is controversial, which means more research and exploration are needed to make more informed decisions regarding the prevention and treatment of CSA-AKI.

BACKGROUND:Mechanical stimulation has been confirmed to promote osteogenic differentiation of bone marrow stromal stem cells,but the mechanism is unknown.Primary cilia are important mechanoreceptors and regulate various signaling pathways such as TGF-β1/BMP-2/SMAD.They are likely to be important targets for mechanical regulation of bone marrow stromal stem cells. OBJECTIVE:To investigate the effect and mechanism of fluid shear stress on osteogenic differentiation of bone marrow stromal stem cells. METHODS:Rat bone marrow stromal stem cells were divided into control group,mechanical stimulation group(fluid shear mechanics intervention by shaking table),mechanical stimulation + IFT88 silencing group(mechanical stimulation + silencing IFT88 expression with siRNA).After 24 hours of intervention,qRT-PCR was utilized to determine the expression of transforming growth factor β1 and bone morphogenetic protein 2.Western blot assay was used to detect the expression of phosphorylated SMAD2/3 protein.Immunofluorescent staining of primary cilia was conducted and morphology was analyzed. RESULTS AND CONCLUSION:Shear stress stimulation could promote the transcriptional activity of transforming growth factor β1 and bone morphogenetic protein 2 genes,and increase the expression of phosphorylated SMAD2/3 protein.After siRNA interfered with primary cilia,this mechanical response effect was significantly reduced.There was a Spearman correlation between the change ratio of the primary cilium area of bone marrow stromal stem cells and the increased ratio of transforming growth factor β1 and bone morphogenetic protein 2 gene transcription.These findings indicate that primary cilia/intraflagellar transport mediates the activation of fluid shear stress-responsive transforming growth factor β1/bone morphogenetic protein 2/SMAD signaling pathway and promotes osteogenic differentiation of bone marrow stromal stem cells.

BACKGROUND:Cervical neutral position magnetic resonance imaging is widely used for the diagnosis and treatment of cervical spondylotic myelopathy.However,it is not possible for patients to maintain the exact same position of the head and neck during repeated cervical magnetic resonance imaging examinations.The cervical spine undergoes minor flexion and extension movements in the sagittal plane,and the head may have a certain degree of variation in flexion and extension.Whether these changes in the neutral position of the cervical spine affect the volume of cervical discs herniation and cervical curvature is unclear. OBJECTIVE:Using artificial intelligence-assisted measurement,this study aimed to analyze the accuracy and reliability of magnetic resonance imaging examinations for measuring the volume of cervical discs herniation and cervical curvature in patients with cervical spondylotic myelopathy undergoing two consecutive cervical neutral positions in the short term. METHODS:A retrospective study was conducted on patients with cervical spondylotic myelopathy who underwent conservative treatment and underwent two consecutive cervical magnetic resonance imaging examinations within three months between June 2012 and June 2023.We proposed the use of occipital-thoracic distance and occipital-thoracic angle to evaluate the variation in flexion and extension of the head in the neutral position of the cervical spine.Based on the changes in occipital-thoracic angle,patients were divided into occipital-thoracic angle increase group and occipital-thoracic angle decrease group.Cervical discs herniation volume,C2-6 Cobb angle,and cervical(C3-C7)curvature were measured using artificial intelligence-assisted measurement software.Normal distribution data were represented by mean±SD,while non-normal distribution data were represented by the median(interquartile range).Spearman's rank correlation coefficient was used to analyze the correlation between changes in Cobb angle,cervical(C3-C7)curvature,and cervical discs herniation volume. RESULTS AND CONCLUSION:(1)A total of 104 patients and 326 cervical discs herniation were included in the study.There were 47 patients in the occipital-thoracic angle increase group and 57 patients in the occipital-thoracic angle decrease group.(2)Extension and flexion index of the head:There were no significant differences in occipital-thoracic distance and occipital-thoracic angle during the initial diagnosis and follow-up examination.The variation of occipital-thoracic distance was 0.035(3.23)mm,and the variation of occipital-thoracic angle was-0.31(3.28)°.The deviation range of occipital-thoracic distance and occipital-thoracic angle was small,and there was no significant correlation.(3)Cervical curvature index:There were no significant differences in C2-6 Cobb angle and C3-C7 curvature during the initial diagnosis and follow-up examination.There were no significant differences in C2-6 Cobb angle and C3-C7 curvature between the occipital-thoracic angle increase group and occipital-thoracic angle decrease group.(4)There was no significant difference in volume of cervical discs herniation during the initial diagnosis and follow-up examination.There was no significant difference in volume of cervical discs herniation between the occipital-thoracic angle increase group and occipital-thoracic angle decrease group.There was no significant correlation between the change of cervical discs herniation volume and the change of C2-6 Cobb angle and the cervical(C3-C7)curvature.(5)These results indicate that in the neutral position of the cervical spine,there were negligible minor flexion and extension movements in the sagittal plane,and the head was limited to a specific position.Although the head has a certain range of flexion and extension variation,it does not affect the accuracy and reliability of parameters including cervical discs herniation volume,C2-6 Cobb angle,and cervical(C3-C7)curvature.