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To explore the influence of cone-beam computed tomography (CBCT) matching reference point selection on target accuracy in intensity-modulated radiotherapy (IMRT) for breast cancer and aimed to provide a reference for clinical application. We conducted a retrospective analysis on breast cancer patients who underwent postoperative radiotherapy between January 2020 and October 2020. CBCT images for image-guided radiotherapy, different matching reference points, and the location of computed tomography (CT) image registration were used to divide patients into the sternum (control group 1), thoracic (control group 2), and sternum-thoracic + target (team) groups. CBCT alignment was confirmed by three different registration methods. After matching, the matching error and spatial displacement of the metal clip at the boundary of the operative cavity in CBCT and target CT were measured and recorded. A total of 528 sets of matching errors and spatial displacement data of metal clips in the target area were obtained for 22 enrolled patients. Independent sample nonparametric tests were used to analyze the significant differences in the three groups of data, and the distance of metal clips in the three groups was calculated. The matching errors of the sternum and study groups were statistically significant, except for the rotation error in the direction of the X-axis (p>0.05). There were no statistically significant differences in the matching error between the thoracic vertebra and the study groups (p>0.05). After the sternum group was matched with the study group, the displacements of the metal clips in the target area of CBCT and CT in the X, Y, and Z directions were as follows: (1.59±1.61) mm and (1.23±1.19) mm (p=0.045), (1.65±1.44) mm and (1.89±1.52) mm (p=0.006), and (1.13±1.18) mm and (1.37±1.31) mm (p=0.999), respectively. The thoracic vertebra group was matched with the study group, and the displacements of the metal clips in the target area of CBCT and CT in the X, Y, and Z directions were as follows: (1.51±1.83) mm and (1.23±1.19) mm (p=0.002), (1.69±1.84) mm and (1.89±1.52) mm (p

In order to improve the property of polyacrylonitrile (PAN) nanofibrous membrane, MgO nanoparticles and Ag nanoparticles (MgONPs and AgNPs) were added into the polyacrylonitrile (PAN) solution. PAN/MgO/Ag composite nanofibrous filtration membranes with different mass fractions of MgO and Ag nanoparticles were prepared through electrospinning method. Their microstructure, crystalline structure, air permeability, moisture permeability and filtration property were tested by scanning electron microscope, X-ray diffractometer, infrared spectrometer, ultraviolet translucency analyzer and filtration property tester. Test results showed that the fiber diameter of pure PAN nanofiber was 222.9 nm while the diameter of PAN/MgO/Ag composite nanofibers were 151.5 nm~258.6 nm. Compared with pure PAN nanofibrous membrane, composite PAN/MgO/Ag nanofibrous membranes possessed excellent filter performance and ultraviolet protective property. Their UV protective factor were 38.73~55.37. The filtration efficiency were 95.36%~97.59% while the pressure drop were 46.06 Pa~58.31 Pa. When the mass fraction of MgONPs and AgNPs were both 0.75%, PAN/MgO/Ag composite nanofibrous membrane had the maximum quality factor of 0.071 4 Pa-1 and the filtration performance was the best, which belonged to the fiber filtration material with higher efficiency and lower resistance and UV protection property. [ABSTRACT FROM AUTHOR]

Properties of PAN/ZnO composite nano fibrous filtration film were studied.ZnO nano particles were added into PAN solution to prepare PAN/ZnO composite nano fibrous filtration film. Its microstructure, air permeability, moisture permeability, ultraviolet protective property and filtration property were tested. Test results showed that diameter of PAN/ZnO composite nano fibrous filtration film was larger, air permeability was increased, moisture permeability was slightly decreased.Filtration efficiency of PAN/ZnO composite nano fibrous filtration film was 98.98%~99.76%. Resistant pressure drop was 82.32 Pa~89.18 Pa. UPF value was 51.03~72.35 and antibacterial rate was 70.1%~99.2%.It is considered that prepared PAN/ZnO composite nano fibrous filtration film has properties like ultraviolet-proof property, antibacterial property, high efficiency & low resistance property and so on. It is a nano fibrous film with multiple functions. [ABSTRACT FROM AUTHOR]

Preparation and property of high-efficiency and low-resistance nanofiber filtration membrane were studied. Organic electret polytetrafluoroethylene (PTFE) was mixed into polyacrylonitrile (PAN) solvent. PAN with mass fraction of 12% and PAN/PTFE blended solvent with PTFE mass fraction of 0, 0.25%, 0.50%, 0.75% and 1.00% respectively were prepared. PAN/PTFE composite nanofiber was prepared by electrospinning technology. Scanning electron microscope, infrared spectrometer, automatic filter material tester and so son were used to analyze the nanofiber membranes structural property and filtration property. The test results showed that PAN/PTFE composite nanofiber had characteristic absorption peaks of PAN. Compared with pure PAN nanofiber membrane, diameter of PAN/PTFE nanofiber was slightly increased. Surface water contact angle, air permeability and tensile strength of the fiber membrane were increased, the surface voltage was increased. As the increase of PTFE mass fractions, an increase trend was shown. Moisture transmission was slightly decreased. As the increase of PTFE mass fraction, a decrease trend was shown. Anti-pollution capacity was increased. Filtration efficiency of PAN/PTFE composite fiber membrane was increased. When spinning time was 30 min and nanofiber membrane surface density was around 0.85 g/m², the filtration efficiency was 92.10%~99.95%, the resistance pressure drop was 48.1 Pa~95.7 Pa. When PTFE mass fraction was 0.75%, quality factor of the fiber membrane was the highest as 0.079 4 Pa-1, the filtration efficiency was 99.95% and the resistance pressure drop was 95.7 Pa. It is considered that addition of PTFE electret can improve filtration property of nanofiber membrane. PAN/PTFE composite fiber membrane prepared belongs to filtration membrane with higher efficiency and lower resistance. It has a certain anti-pollution capability. [ABSTRACT FROM AUTHOR]