Design of a mixed material moderator in a beam-shaping assembly for proton accelerator-based boron neutron capture therapy.

Boron Neutron Capture Therapy is being promoted with the development of accelerator neutron sources, and many new accelerator-based BNCT facilities are being built. In Particle Accelerator Facility project of Sun Yat-sen University, we plan to build a terminal for BNCT research based on an 8 MeV, CW 3 mA proton accelerator. In this paper, we present a beam-shaping assembly for this proton accelerator with such low 24 kW beam power, using composite moderator materials composed of five elements: Mg, Al, F, O, and Li. The calculation result of FLUKA with ENDF/B and JENDL libraries shows that the epithermal neutron beam flux is 1.57×109n/cm2/s with the CW 3 mA proton beam. The fast neutron component and the gamma ray component under free-air condition are 1.49×10-13Gy∙cm2 and 8.12×10-14Gy∙cm2 respectively, in line with IAEA-TECDOC-1223 design recommendations. The thermal analysis shows that the maximum temperature of beryllium target is 706.5 K, and the structure materials of BSA do not melt.

Efficient optimization of an accelerator neutron source for neutron capture therapy using genetic algorithms.

BACKGROUND: In recent years, genetic algorithms have been applied in the field of nuclear technology design, producing superior optimization results compared to traditional methods. They can be employed in the design and optimization of beam shaping assemblies (BSA) BSA to obtain the desired neutron beams. But it should be noted that the direct combination of Monte Carlo methods with genetic algorithms requires a significant amount of computational resources and time. PURPOSE: Design and optimize BSA more efficiently to achieve neutron beams that meet specified recommendations. METHODS: We propose an approach of NSGA II with crucial variables which are identified by multivariate statistical techniques. This approach significantly reduces the problem sizes, thus reducing the time required for optimization. We illustrate this methodology using the example of BSA design for AB-BNCT. RESULTS: The computational efficiency has tripled with crucial variables. By using NSGA II, we obtained optimized models conforming to both the new and old version IAEA BNCT guidelines through a single optimization process and subjected them to phantom analysis. The results demonstrate that models obtained through this method can meet the IAEA recommendations with deep advantage depth (AD) and high absorbed ratio (AR). CONCLUSION: The genetic algorithm with crucial variables displays tremendous potential in addressing BSA optimization challenges.

Risk factors for pulmonary embolism in lung cancer patients with lower limb deep venous thrombosis: a case-control study.

Background: There is growing evidence that misdiagnosis contributes to the high mortality rate in lung cancer patients complicated with pulmonary embolism (PE). This current study analyzed predictors of PE in lung cancer patients with lower extremity deep venous thrombosis (DVT) with the aim of personalizing the treatment and management of patients with PE. Methods: This retrospective case-control study included lung cancer patients with DVT at the emergency department of Shanghai Chest Hospital from January 2018 to December 2019. Patients were classified as having DVT with or without PE. The following characteristics were examined, including age, gender, smoking, hypertension, surgical trauma, hyperlipidemia, long-term bedridden status, calf swelling, coronary heart disease, chronic pulmonary disease, DVT location, DVT type, prothrombin time (PT), international normalized ratio (INR), activated partial thromboplastin time (APTT), thrombin time (TT), fibrinogen, and D-dimer, and univariate and multivariate analyses were performed. Results: A total of 90 patients with lung cancer and DVT were analyzed, of whom 60% (54/90) had PE. Those variables independently associated to PE were hypertension [odds ratio (OR): 7.883, 95% confidence interval (CI): 2.038-30.495, P=0.003], long-term bedridden status (OR: 4.166, 95% CI: 1.236-14.044, P=0.021), and D-dimer levels (OR: 2.123, 95% CI: 1.476-3.053, P=0.000) were identified as independent risk factors for PE. The cut-off value of the receiver operating characteristic (ROC) curve for predicting PE by presented scoring system according to the risk factors was 1.5 and the area under the curve (AUC) was 0.84 (P<0.001). Conclusions: Hypertension, being bedridden for an extended period, and elevated serum D-dimer levels were independent risk factors of PE in lung cancer patients with lower extremity DVT. Novel strategies for patient management should be developed to decrease the risk of PE.

Phosphorylated biomass-derived porous carbon material for efficient removal of U(VI) in wastewater.

A simple strategy to prepare cost-effective adsorbent materials for the removal of U(VI) in radioactive wastewater is of great significance to environmental protection. Here, activated orange peel was used as a precursor for the synthesis of biomass charcoal, and then a phosphorylated honeycomb-like porous carbon (HLPC-PO4) material was prepared through simple phosphorylation modification. FT-IR and XPS showed that P-O-C, P-C, and PË­O bonds appeared in HLPC-PO4, indicating that the phosphorylation process is mainly the reaction of C-O bonds on the surface of the material with -PO4. The results of the batch experiments showed that the uptake equilibrium of HLPC-PO4 to U(VI) occurred within 20 min, and the kinetic simulation showed that the process was monolayer chemical adsorption. Interestingly, the maximum U(VI) uptake capacity of HLPC-PO4 at T = 298.15 K and pH = 6.0 was 552.6 mg/g, which was more than 3 times that of HLPC. In addition, HLPC-PO4 showed an adsorption selectivity of 70.1% for U(VI). After 5 cycles, HLPC-PO4 maintained its original adsorption capacity of 90.5%. The adsorption mechanism can be explained as the complexation of U(VI) with P-O and PË­O on the surface of the adsorbent, confirming the strong bonding ability of -PO4 to U(VI).

Novel esophageal squamous cell carcinoma bone metastatic clone isolated by scintigraphy, X ray and micro PET/CT.

AIM: To establish a Chinese esophageal squamous cell carcinoma (ESCC) cell line with high bone metastasis potency using (99m)Tc-methylene diphosphonate ((99m)Tc-MDP) micro-pinhole scintigraphy, X ray and micro-positron emission tomography/computed tomography (PET/CT) for exploring the mechanism of occurrence and development in esophageal cancer. METHODS: The cells came from a BALB/c nu/nu immunodeficient mouse, and oncogenic tumor tissue was from a surgical specimen from a 61-year-old male patient with ESCC. The cell growth curve was mapped and analysis of chromosome karyotype was performed. Approximately 1 × 106 oncogenic cells were injected into the left cardiac ventricle of immunodeficient mice. The bone metastatic lesions of tumor-bearing mice were detected by (99m)Tc-MDP scintigraphy, micro-PET/CT and X-ray, and were resected from the mice under deep anesthesia. The bone metastatic cells in the lesions were used for culture and for repeated intracardiac inoculation. This in vivo/in vitro experimental metastasis study was repeated for four cycles. All of the suspicious bone sites were confirmed by pathology. Real-time polymerase chain reaction was used to compare the gene expression in the parental cells and in the bone metastatic clone. RESULTS: The surgical specimen was implanted subcutaneously in immunodeficient mice and the tumorigenesis rate was 100%. First-passage oncogenic cells were named CEK-Sq-1. The chromosome karyotype analysis of the cell line was hypotriploid. The bone metastasis rate went from 20% with the first-passage oncogenic cells via intracardiac inoculation to 90% after four cycles. The established bone metastasis clone named CEK-Sq-1BM had a high potential to metastasize in bone, including mandible, humerus, thoracic and lumbar vertebrae, scapula and femur. The bone metastasis lesions were successfully detected by micro-pinhole bone scintigraphy, micro-PET/CT, and X-ray. The sensitivity, specificity and accuracy of the micro-pinhole scintigraphy, X-ray, and micro-PET/CT imaging examinations were: 89.66%/32%/80%, 88.2%/100%/89.2%, and 88.75%/77.5%/87.5%, respectively. Some gene expression difference was found between parental and bone metastasis cells. CONCLUSION: This newly established Chinese ESCC cell line and animal model may provide a useful tool for the study of the pathogenesis and development of esophageal carcinoma.

[The effect of exercise during hemodialysis on adequacy of dialysis].

OBJECTIVE: To investigate the effect of exercise on dialysis adequacy during hemodialysis (HD). METHODS: 20 studies were performed in 20 maintenance hemodialysis patients. Each study consisted of a pair of HD treatment; the blood and dialysate flow rates, dialyser and treating time were the same. An adapted exercise cycle was attached to the dialysis bed. The patients of exercise group pedaled the exercise cycle throughout the dialysis, and had a 5 - 10 minutes rest if they needed. while the patients of a control group had no exercise. BUN, Scr and UA were measured just before and after dialysis immediately, and 60 minutes after dialysis. Furthermore, KT/V, SRI, AUR and nPCR were detected by on-line dialysis monitor. RESULTS: In the exercise group, after HD, both BUN and Scr decrease rates were significantly higher, while the rebound of BUN, Scr and UA were significantly lower than those in the control group (P < 0.05 approximately 0.01). KT/V, AUR and SRI were significant higher in the exercise group than those in the control group (P < 0.05 approximately 0.01 respectively), while nPCR showed no significant difference between the two groups. CONCLUSION: Exercise during HD is a practicable new way to improve the efficiency of dialysis.