<strong>Purpose:</strong> <span style="font-family:""><span style="font-family:Verdana;">The study is aimed to establish the dosimetric characteristics of field-in-fiel...<strong>Purpose:</strong> <span style="font-family:""><span style="font-family:Verdana;">The study is aimed to establish the dosimetric characteristics of field-in-field (FiF) technique for carcinoma of breast treatment in Nepal. We assumed that FIF technique may result in improved dose distribution and reduced acute toxicity in these patients. </span><b><span style="font-family:Verdana;">Methods: </span></b><span style="font-family:Verdana;">Forty breast cancer patient</span></span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> participated in this study. A total dose of 50 Gy in 25 fractions was prescribed to the planning target volume. FiF plan was generated in treatment planning system. Dose volume histograms w</span><span style="font-family:Verdana;">ere</span><span style="font-family:""><span style="font-family:Verdana;"> evaluated for PTV and organs at risks. Several parameters were analyzed for the PTVs and organ at risks (OARs) together with the Conformity index (CI), and the Homogeneity index (HI). </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">The dose coverage of breast volume was achieved. The V</span><sub><span style="font-family:Verdana;">95%</span></sub><span style="font-family:Verdana;"> (volume of 95%) of PTV covered D</span><sub><span style="font-family:Verdana;">95%</span></sub><span style="font-family:Verdana;"> (Dose of 95%). The PTV dose was covered to 49.98 ± 0.9 Gy and 49.81 ± 1.1 Gy for the left and right breast, respectively. The mean lung dose was 14.87 ± 0.91 Gy. The homogeneity index (0.26 ± 0.17 and 0.22 ± 0.13) and conformity index (1.59 ± 0.75 and 1.36 ± 0.45) were analyzed for left and right breast, respectively. </span><b><span style="font-family:Verdana;">Conclusion: </span></b><span style="font-family:Verdana;">The study supports the viability of FiF technique in the treatment of breast cancer in Nepal. The FIF technique enables better dose distribution in the PTV and reduces dose to OARs. The FiF technique provides dosimetric advantages and requires less planning time.</span></span>展开更多
In this work,a tapered fluidized bed(TFB)without a distributor for fluidizing carbon nanotube(CNT)was applied for improving the dead zone,blockage,and fracture of distributor,which occurred in actual production.Experi...In this work,a tapered fluidized bed(TFB)without a distributor for fluidizing carbon nanotube(CNT)was applied for improving the dead zone,blockage,and fracture of distributor,which occurred in actual production.Experiments were performed under different superficial gas velocities,static bed heights,CNT agglomerate size,and positions of pressure probe.To obtain multi-perspective and multi-scale understanding of fluidization dynamics of gas–CNT flow in the TFB without a distributor,the standard deviation,skewness,kurtosis,wavelet decompositions and homogeneous index analysis methods were adopted.Some noticeable phenomena were observed.Particle movements including inter-particle,gas–particle and particle–wall dominate dynamic characteristics.The amplitudes of pressure fluctuations of coarse agglomerated multi-walled CNT were more sensitive to the gas velocity than that of fine agglomerated multi-walled CNT.The sensitively of energy contribution of the meso-and macrostructures was that the sensitivity of the measured position was less than the sensitivity of the energy contribution by the changes of particle size,and the sensitivity of the energy contribution by the changes of particle size was less than the energy contribution by the changes of gas velocity.The fluidization quality of coarse agglomerated multi-walled CNT was better than that of fine agglomerated multi-walled CNT,which was verified by the skewness and wavelet analysis.展开更多
The size of the rock specimen affects the stress concentrates in the vicinity of the top/bottom of the rock specimen during the evaluation of the geomechanical parameters in the laboratory,which causes un-reliable res...The size of the rock specimen affects the stress concentrates in the vicinity of the top/bottom of the rock specimen during the evaluation of the geomechanical parameters in the laboratory,which causes un-reliable results.However,the appropriate size for geomechanical evaluation is not well understood yet because of limitations in the sampling and analysis.In this study,a series of numerical simulations using a finite element package was conducted to investigate the effect of sample aspect ratio,fluid saturation,and porosity,on the mechanical behavior of the rock under elastic and poroelastic conditions.In addition,two concepts,stress/strain homogeneity index(SHI)and representative elementary volume(REV),were developed to find out the appropriate sample size.The results show that the presence of stiff platens,which are dissimilar to the specimen material,causes significant stress concentration in the two ends of the specimen.The concentration of stress in the specimen reduces when the aspect ratio increases.An optimum aspect ratio(length-to-diameter equal to 3)was observed by SHI analysis which after that the changes in stress concentration are insignificant.The REV size analysis confirms the obtained optimum aspect ratio by SHI analysis.The saturated specimens show a lower magnitude of stress than applied stress because of the presence of pore pressure,which can carry a portion of the stress.The higher void ratio results in lower strength of the specimen.This study could be beneficial for the better design of geomechanical tests to have reliable results.展开更多
文摘<strong>Purpose:</strong> <span style="font-family:""><span style="font-family:Verdana;">The study is aimed to establish the dosimetric characteristics of field-in-field (FiF) technique for carcinoma of breast treatment in Nepal. We assumed that FIF technique may result in improved dose distribution and reduced acute toxicity in these patients. </span><b><span style="font-family:Verdana;">Methods: </span></b><span style="font-family:Verdana;">Forty breast cancer patient</span></span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> participated in this study. A total dose of 50 Gy in 25 fractions was prescribed to the planning target volume. FiF plan was generated in treatment planning system. Dose volume histograms w</span><span style="font-family:Verdana;">ere</span><span style="font-family:""><span style="font-family:Verdana;"> evaluated for PTV and organs at risks. Several parameters were analyzed for the PTVs and organ at risks (OARs) together with the Conformity index (CI), and the Homogeneity index (HI). </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">The dose coverage of breast volume was achieved. The V</span><sub><span style="font-family:Verdana;">95%</span></sub><span style="font-family:Verdana;"> (volume of 95%) of PTV covered D</span><sub><span style="font-family:Verdana;">95%</span></sub><span style="font-family:Verdana;"> (Dose of 95%). The PTV dose was covered to 49.98 ± 0.9 Gy and 49.81 ± 1.1 Gy for the left and right breast, respectively. The mean lung dose was 14.87 ± 0.91 Gy. The homogeneity index (0.26 ± 0.17 and 0.22 ± 0.13) and conformity index (1.59 ± 0.75 and 1.36 ± 0.45) were analyzed for left and right breast, respectively. </span><b><span style="font-family:Verdana;">Conclusion: </span></b><span style="font-family:Verdana;">The study supports the viability of FiF technique in the treatment of breast cancer in Nepal. The FIF technique enables better dose distribution in the PTV and reduces dose to OARs. The FiF technique provides dosimetric advantages and requires less planning time.</span></span>
基金supported by the National Natural Science Foundation of China(No.51676103)Taishan Scholar Project of Shandong Province(No.ts20190937)。
文摘In this work,a tapered fluidized bed(TFB)without a distributor for fluidizing carbon nanotube(CNT)was applied for improving the dead zone,blockage,and fracture of distributor,which occurred in actual production.Experiments were performed under different superficial gas velocities,static bed heights,CNT agglomerate size,and positions of pressure probe.To obtain multi-perspective and multi-scale understanding of fluidization dynamics of gas–CNT flow in the TFB without a distributor,the standard deviation,skewness,kurtosis,wavelet decompositions and homogeneous index analysis methods were adopted.Some noticeable phenomena were observed.Particle movements including inter-particle,gas–particle and particle–wall dominate dynamic characteristics.The amplitudes of pressure fluctuations of coarse agglomerated multi-walled CNT were more sensitive to the gas velocity than that of fine agglomerated multi-walled CNT.The sensitively of energy contribution of the meso-and macrostructures was that the sensitivity of the measured position was less than the sensitivity of the energy contribution by the changes of particle size,and the sensitivity of the energy contribution by the changes of particle size was less than the energy contribution by the changes of gas velocity.The fluidization quality of coarse agglomerated multi-walled CNT was better than that of fine agglomerated multi-walled CNT,which was verified by the skewness and wavelet analysis.
文摘The size of the rock specimen affects the stress concentrates in the vicinity of the top/bottom of the rock specimen during the evaluation of the geomechanical parameters in the laboratory,which causes un-reliable results.However,the appropriate size for geomechanical evaluation is not well understood yet because of limitations in the sampling and analysis.In this study,a series of numerical simulations using a finite element package was conducted to investigate the effect of sample aspect ratio,fluid saturation,and porosity,on the mechanical behavior of the rock under elastic and poroelastic conditions.In addition,two concepts,stress/strain homogeneity index(SHI)and representative elementary volume(REV),were developed to find out the appropriate sample size.The results show that the presence of stiff platens,which are dissimilar to the specimen material,causes significant stress concentration in the two ends of the specimen.The concentration of stress in the specimen reduces when the aspect ratio increases.An optimum aspect ratio(length-to-diameter equal to 3)was observed by SHI analysis which after that the changes in stress concentration are insignificant.The REV size analysis confirms the obtained optimum aspect ratio by SHI analysis.The saturated specimens show a lower magnitude of stress than applied stress because of the presence of pore pressure,which can carry a portion of the stress.The higher void ratio results in lower strength of the specimen.This study could be beneficial for the better design of geomechanical tests to have reliable results.
