AIM To analyse clinical and dosimetric results of helical tomotherapy(HT) and volumetric modulated arc therapy(VMAT) in complex adjuvant breast and nodes irradiation.METHODS Seventy-three patients were included(31 HT ...AIM To analyse clinical and dosimetric results of helical tomotherapy(HT) and volumetric modulated arc therapy(VMAT) in complex adjuvant breast and nodes irradiation.METHODS Seventy-three patients were included(31 HT and 42 VMAT). Dose were 63.8 Gy(HT) and 63.2 Gy(VMAT) in the tumour bed, 52.2 Gy in the breast, 50.4 Gy in supraclavicular nodes(SCN) and internal mammary chain(IMC) with HT and 52.2 Gy and 49.3 Gy in IMC and SCN with VMAT in 29 fractions. Margins to particle tracking velocimetry were greater in the VMAT cohort(7 mm vs 5 mm).RESULTS For the HT cohort, the coverage of clinical target volumes was as follows: Tumour bed: 99.4% ± 2.4%; breast: 98.4% ± 4.3%; SCN: 99.5% ± 1.2%; IMC:96.5% ± 13.9%. For the VMAT cohort, the coverage was as follows: Tumour bed: 99.7% ± 0.5%, breast: 99.3% ± 0.7%; SCN: 99.6% ± 1.4%; IMC: 99.3% ± 3%. For ipsilateral lung, Dmean and V20 were 13.6 ± 1.2 Gy, 21.1% ± 5%(HT) and 13.6 ± 1.4 Gy, 20.1% ± 3.2%(VMAT). Dmean and V30 of the heart were 7.4 ± 1.4 Gy, 1% ± 1%(HT) and 10.3 ± 4.2 Gy, 2.5% ± 3.9%(VMAT). For controlateral breast Dmean was 3.6 ± 0.2 Gy(HT) and 4.6 ± 0.9 Gy(VMAT). Acute skin toxicity grade 3 was 5% in the two cohorts.CONCLUSION HT and VMAT in complex adjuvant breast irradiation allow a good coverage of target volumes with an acceptable acute tolerance. A longer follow-up is needed to assess the impact of low doses to healthy tissues.展开更多
Objective: To evaluate the short-term clinical outcomes of intracranial germinoma patients treated with craniospinal irradiation(CSI) using helical tomotherapy(HT) system in our center. Methods: Twenty-three patients ...Objective: To evaluate the short-term clinical outcomes of intracranial germinoma patients treated with craniospinal irradiation(CSI) using helical tomotherapy(HT) system in our center. Methods: Twenty-three patients who were treated with CSI in our center from January 2008 to July 2012 were collected, with an average age of 20. All of the patients' CSI used the HT system. The total doses were 27-36 Gy/15-20 F(1.5-2 Gy per fraction), and total local doses were 46-60 Gy/30-50 F(5 fractions per week). All female patients for CSI were treated with left-right parallel-opposed field irradiation to protect their ovarian functions. Median follow-up time was 30.9 months(range, 5-67 months). The SPSS19.0 software was used, and the overall survival(OS) was calculated using the Kaplan-Meier method.Results: Among 17 patients with assessable tumors, 9 cases(52.9%) were CR, 7 cases(41.2%) were PR, and 1 case(5.9%) was SD. Hematological toxicity was the severest side-effect occurred in the procedure of CSI. The level 1-4 acute leukopenia were 8.7%, 30.4%, 34.8% and 21.7% and the level 1-4 acute thrombopenia were 8.7%, 30.4%, 21.7% and 8.7%, respectively.Conclusions: For primary intracranial germinomas, HT can be used to implement CSI for simplifying radiotherapy procedures, improving radiotherapy accuracy, enhancing protection of peripheral organs at risk(ORA) and guaranteeing therapeutic effects. With the acceptable acute and long-term toxicity, CSI using HT in intracranial germinoma patients can be a safe and alternative mode.展开更多
Whole brain radiotherapy (WBRT) remains the standard management of breast cancer patients with brain metastases, allowing for symptomatic improvement and good local control in most patients. However, its results remai...Whole brain radiotherapy (WBRT) remains the standard management of breast cancer patients with brain metastases, allowing for symptomatic improvement and good local control in most patients. However, its results remain suboptimal in terms of both efficacy and toxicity. In highly selected breast cancer patients, stereotaxic radiotherapy demonstrates a very good local control with a low toxicity. With the purpose of improving the efficacy/toxicity ratio, we report the association of integrated boost with WBRT in a breast cancer patient with brain metastases. Two and a half years after completion of helical tomotherapy (HT), the patient experienced clinical and radiological complete remission of her brain disease. No delayed toxicity occurred and the patient kept her hair without need of radiosurgical procedure. The HT provided a high dosimetric homogeneity, delivering integrated radiation boosts, and avoiding critical structures involved in long-term neurological toxicity. Further assessment is required and recruitment of breast cancer patients into clinical trials is encouraged.展开更多
Radiotherapy for locally advanced pancreatic cancer is technically difficult and frequently associated with high-grade digestive toxicity.Helical tomotherapy(HT)is a new irradiation modality that combines megavoltage ...Radiotherapy for locally advanced pancreatic cancer is technically difficult and frequently associated with high-grade digestive toxicity.Helical tomotherapy(HT)is a new irradiation modality that combines megavoltage computed tomography imaging for patient positioning with intensity-modulated fan-beam radiotherapy.Its recent availability opens new fields of exploration for pancreatic radiotherapy as a result of its ability to tailor very well-defined dose distributions around the target volumes.Here,we report the use of HT in two patients with locally advanced pancreatic cancer. Doses to the bowel,kidneys and liver were reduced significantly,which allowed for excellent treatment tolerance without any high-grade adverse effects in either patient.展开更多
Purpose: Craniospinal axis irradiation (CSI) is a method of treating various central nervous system malignancies. The large target volume typically includes entire spinal cord and whole brain. Dosimetric comparison wa...Purpose: Craniospinal axis irradiation (CSI) is a method of treating various central nervous system malignancies. The large target volume typically includes entire spinal cord and whole brain. Dosimetric comparison was performed between tomotherapy, volumetric modulated arc therapy (VMAT), and 3D conformal radiation therapy (3D-CRT) for CSI. Methods and Materials: Five (n = 5) CSI patients were planned using 3D-CRT, VMAT, and tomotherapy (normalized such that 95% of PTV received at least 23.4 Gy in 13 fractions). Plans were compared using PTV conformity number (CN) and homogeneity index (HI), normal tissue (NT) dose statistics, integral dose, and treatment time. Results: On average, tomotherapy plans showed higher CN (0.932 vs. 0.860 and 0.672 for SmartArc and 3D-CRT). In terms of HI, VMAT plans consistently showed better dose homogeneity (1.07 vs. 1.15 and 1.13 for tomotherapy and 3D-CRT). SmartArc delivered lower maximum dose for majority of NT, but higher mean dose. 3D-CRT plans delivered higher maximum dose but lower mean dose to NT. Conclusions: SmartArc treatments achieved better PTV homogeneity and reduced maximum dose to NT. Tomotherapy showed better target conformity, but 3D-CRT was shown to reduce mean dose to NT. Integral doses were similar between treatment modalities, but tomotherapy treatment times were much longer.展开更多
Purpose: To evaluate the accuracy of deformable image registration (DIR) between the planning kVCT (pCT) and the daily MVCT combined with the histogram matching (HM) algorithm, and evaluate the deformable dose accumul...Purpose: To evaluate the accuracy of deformable image registration (DIR) between the planning kVCT (pCT) and the daily MVCT combined with the histogram matching (HM) algorithm, and evaluate the deformable dose accumulation using a suggested method for adaptive radiotherapy with Helical Tomotharapy (HT). Methods: For five prostate cancer patients (76 Gy/38 Fr) treated with HT in our institution, seven MVCT series (a total of 35 series) acquired weekly were investigated. First, to minimize the effect of different HU values between pCT and MVCT, this image-processing method adjusts HU values between pCT and MVCT images by using image cumulative histograms of HU values, generating an HM-MVCT. Then, the DIR of the pCT to the HM-MVCT was performed, generating a deformed pCT. Finally, deformable dose accumulation was performed toward the pCT image. Results: The accuracy of DIR was significantly improved by using the HM algorithm, compared with non-HM method for several structures (p ±0.05, 0.83 ±0.06, and 0.90 ± 0.04 for the CTV, rectum, and bladder, respectively, while that of the HM method was 0.81 ±0.06, 0.81 ±0.04, and 0.92 ±0.06, respectively. For the deformable dose accumulation, some difference was observed between the two methods, particularly for the small calculated regions, such as rectum V60 and V70. Conclusion: Adapting the HM method can improve the accuracy of DIR. Furthermore, dose calculation using the deformed pCT using HM methods can be an effective tool for adaptive radiotherapy.展开更多
To evaluate the efficacy and feasibility of external beam radiotherapy(EBRT) for duodenal adenocarcinoma in an 84-year-old female who underwent EBRT(2.2 Gy/d for a total dose of 46.2 Gy) using helical tomotherapy(HT)....To evaluate the efficacy and feasibility of external beam radiotherapy(EBRT) for duodenal adenocarcinoma in an 84-year-old female who underwent EBRT(2.2 Gy/d for a total dose of 46.2 Gy) using helical tomotherapy(HT). Toxicity was evaluated on the National Cancer Institute's common toxicity criteria(CTCAE 3.0). The patient completed the treatment without G3-G4 toxicity. After 22-mo follow-up, she is alive and well, in complete remission with no late side effects. HT seems to be feasible and effective for duodenal adenocarcinoma in old to very old patients.展开更多
Purpose: Nasal lymphoma created dosimetric challenges in radiotherapy due to the complex anatomical structures. This study was to evaluate the efficacy and toxicity of helical Tomotherapy (HT) in the treatment of nasa...Purpose: Nasal lymphoma created dosimetric challenges in radiotherapy due to the complex anatomical structures. This study was to evaluate the efficacy and toxicity of helical Tomotherapy (HT) in the treatment of nasal NK/T-cell lymphoma (NKTCL) patients. Methods and Materials: Between August 2008 and April 2013, a total of 25 NKTCL patients were treated with HT in our department;Among them, three patients have not received chemotherapy, one patient has received concurrent chemo-radiation with CHOP plus L-ASP, two patients have received the sequential chemotherapy regimen following irradiation, and all the others have received 1 - 2 cycles of induction chemotherapy followed by irradiation and then with sequential chemotherapy. CHOP-L with 1 - 7 cycles (median: 4 cycles) was utilized as the main chemotherapy regimen. As for HT, the gross tumor volume (GTV) received target doses (TD) ranging from 50 to 56 Gy (median: 50 Gy) at 2 - 2.78 Gy per fraction;and the clinical target volume (CTV) from 36 to 50 Gy (median: 40 Gy) at 1.6 - 2 Gy per fraction. Results: For those patients who had received irradiation, thirteen achieved complete remission (CR), four partial responses (PR);four had progressive disease (PD), two were lost to follow-up, two died within one month after irradiation and were not followed. In 21 patients with follow-up records, the overall response (CR + PR) was 81.0% with the 3-year survival rate of 87.2%, and the mean survival time was 52.8 months [95% confidence interval (CI): 45.2 - 60.4 months]. After radiotherapy the majority of patients had dry mouth and taste changes in varying degrees, and a small portion of patients had compromised hearing or vision functions. No brain injury symptoms occurred during radiation radiotherapy. Conclusions: As compared with conventional three-dimensional conformal radiotherapy (3D-CRT) and intensity modulated radiation therapy (IMRT) performed with HT, HT appears to have more favorable efficacy and toxicity profiles in the treatment of NKTCL. Further systematic and randomized clinical research is under investigation.展开更多
Electromagnetic stirring is one of the widely applied techniques to modify the quality of casting billets.Different from conventional rotate stirring,the helical stirring is more professional in assisting multi-dimens...Electromagnetic stirring is one of the widely applied techniques to modify the quality of casting billets.Different from conventional rotate stirring,the helical stirring is more professional in assisting multi-dimensional flow of molten metal and eliminating solidification defects.In this study,the single-winding helical stirring(SWHS)was introduced,offering advantages such as smaller volume and lower electromagnetic shielding compared to traditional helical stirring methods.Following a comprehensive numerical simulation,the stirring parameters of SWHS were adjusted to yoke inclination angle of 43°and frequency of 12 Hz.The higher electromagnetic force and flow velocity in drawing direction,as well as the lower temperature gradient induced by the SWHS,are positive factors for homogeneous solidification of billet.The experimental results on Al-8%Si alloy and 0.4%C-1.1%Mn steel demonstrate that compared to rotate stirring,the SWHS process can induce better billet quality and is more effective in accelerating the equiaxed expansion and reducing element segregation.The SWHS process can enhance the equiaxed ratio of the billet by 58.3%and reduce segregation degree of carbon element by 10.97%.Consequently,SWHS holds great promise as a potential approach for improving the quality of continuous casting billets.展开更多
Helical anchor is a kind of novel foundation for floating offshore wind turbines,which should be subjected to combined tensile loading caused by wind,wave and current.However,the research about the capacity of helical...Helical anchor is a kind of novel foundation for floating offshore wind turbines,which should be subjected to combined tensile loading caused by wind,wave and current.However,the research about the capacity of helical anchor was mainly examined under uniaxial loading and scarcely explored under combined loading.In this study,three-dimensional finite element limit analysis is adopted to assess the bearing capacities of single-plate rigid helical anchors with different ratios of helix to shaft diameter,D_(H)/D_(S) and embedment ratios L/D_(S).Result shows that the vertical,horizontal and moment bearing capacities increase with increasing D_(H)/D_(S) and L/D_(S).The normalized V-H failure envelopes expands with increasing L/D_(S),while the normalized V-M failure envelopes tend to contract with the increase of D_(H)/D_(S).With increasing D_(H)/D_(S) or decreasing L/D_(S),the normalized H-M failure envelopes expand when the horizontal and moment loading act in the same direction and contract when they act in the opposite direction.The effect of D_(H)/D_(S) and L/D_(S) on the shape of H-M failure envelope become insignificant when L/D_(S)≥4.A series of failure mechanisms under different loading conditions were observed and can be used to explain the trend.Besides,a series of approximate expressions were proposed to fit the uniaxial bearing capacities and the failure envelopes.展开更多
In this paper, the problem of finding exact solutions to the magnetohydrodynamic(MHD) equations in the presence of incompressible mass flows with helical symmetry is considered. For ideal flows, a similarity reduction...In this paper, the problem of finding exact solutions to the magnetohydrodynamic(MHD) equations in the presence of incompressible mass flows with helical symmetry is considered. For ideal flows, a similarity reduction method is used to obtain exact solutions for several MHD flows with nonlinear variable Mach number. For resistive flows parallel to a magnetic field, the governing equilibrium equation is derived. The MHD equilibrium state of a helically symmetric incompressible flow is governed by a second-order elliptic partial differential equation(PDE) for the helical magnetic flux function. Exact solutions for the latter equation are obtained. Also, the equilibrium equations of a gravitating plasma with incompressible flow are derived.展开更多
The aim of this study is the numerical analysis of the melting process of the phase change material(PCM)in a spiral coil.The space between the inner tube and outer shell is filled with RT-50 as PCM.Moreover,the hybrid...The aim of this study is the numerical analysis of the melting process of the phase change material(PCM)in a spiral coil.The space between the inner tube and outer shell is filled with RT-50 as PCM.Moreover,the hybrid nanofluid(with a carbon component)flows through the inner tube.The novelty of this work is to use different configurations of fin and different percentage of hybrid nanoparticles(SWCNTs-Cu O)on the PCM melting process.In the numerical model created by ANSYS-Fluent,the effect of various inlet temperatures is investigated.The results indicate that the extended surface created by extra fin has a dominant effect on melting time,so by adding the third fin,the melting time is reduced by 39.24%.The next most influential factor in PCM melting is the inlet temperature of the working fluid,so that 10°C increment of temperature result in the PCM melting time decreased by 35.41%.展开更多
The goal of this research is to look at multi-target optimization of a two-stage helical gearbox in order to determine the best key design elements for reducing gearbox height and enhancing gearbox efficiency.To do th...The goal of this research is to look at multi-target optimization of a two-stage helical gearbox in order to determine the best key design elements for reducing gearbox height and enhancing gearbox efficiency.To do this,the method known as Taguchi and GRA(Grey Relation Analysis)were used in two stages to address the problem.The single-objective optimization problem was addressed first to close the gap between variable levels,and then the multi-objective optimization problem was solved to determine the best primary design variables.The first and second stage CWFWs(Coefficients of Wheel Face Width),ACS(Permissible Contact Stresses),and first stage gear ratio were also calculated.The study’s findings were utilized to identify the best values for five critical design aspects of a two-stage helical gearbox.展开更多
文摘AIM To analyse clinical and dosimetric results of helical tomotherapy(HT) and volumetric modulated arc therapy(VMAT) in complex adjuvant breast and nodes irradiation.METHODS Seventy-three patients were included(31 HT and 42 VMAT). Dose were 63.8 Gy(HT) and 63.2 Gy(VMAT) in the tumour bed, 52.2 Gy in the breast, 50.4 Gy in supraclavicular nodes(SCN) and internal mammary chain(IMC) with HT and 52.2 Gy and 49.3 Gy in IMC and SCN with VMAT in 29 fractions. Margins to particle tracking velocimetry were greater in the VMAT cohort(7 mm vs 5 mm).RESULTS For the HT cohort, the coverage of clinical target volumes was as follows: Tumour bed: 99.4% ± 2.4%; breast: 98.4% ± 4.3%; SCN: 99.5% ± 1.2%; IMC:96.5% ± 13.9%. For the VMAT cohort, the coverage was as follows: Tumour bed: 99.7% ± 0.5%, breast: 99.3% ± 0.7%; SCN: 99.6% ± 1.4%; IMC: 99.3% ± 3%. For ipsilateral lung, Dmean and V20 were 13.6 ± 1.2 Gy, 21.1% ± 5%(HT) and 13.6 ± 1.4 Gy, 20.1% ± 3.2%(VMAT). Dmean and V30 of the heart were 7.4 ± 1.4 Gy, 1% ± 1%(HT) and 10.3 ± 4.2 Gy, 2.5% ± 3.9%(VMAT). For controlateral breast Dmean was 3.6 ± 0.2 Gy(HT) and 4.6 ± 0.9 Gy(VMAT). Acute skin toxicity grade 3 was 5% in the two cohorts.CONCLUSION HT and VMAT in complex adjuvant breast irradiation allow a good coverage of target volumes with an acceptable acute tolerance. A longer follow-up is needed to assess the impact of low doses to healthy tissues.
文摘Objective: To evaluate the short-term clinical outcomes of intracranial germinoma patients treated with craniospinal irradiation(CSI) using helical tomotherapy(HT) system in our center. Methods: Twenty-three patients who were treated with CSI in our center from January 2008 to July 2012 were collected, with an average age of 20. All of the patients' CSI used the HT system. The total doses were 27-36 Gy/15-20 F(1.5-2 Gy per fraction), and total local doses were 46-60 Gy/30-50 F(5 fractions per week). All female patients for CSI were treated with left-right parallel-opposed field irradiation to protect their ovarian functions. Median follow-up time was 30.9 months(range, 5-67 months). The SPSS19.0 software was used, and the overall survival(OS) was calculated using the Kaplan-Meier method.Results: Among 17 patients with assessable tumors, 9 cases(52.9%) were CR, 7 cases(41.2%) were PR, and 1 case(5.9%) was SD. Hematological toxicity was the severest side-effect occurred in the procedure of CSI. The level 1-4 acute leukopenia were 8.7%, 30.4%, 34.8% and 21.7% and the level 1-4 acute thrombopenia were 8.7%, 30.4%, 21.7% and 8.7%, respectively.Conclusions: For primary intracranial germinomas, HT can be used to implement CSI for simplifying radiotherapy procedures, improving radiotherapy accuracy, enhancing protection of peripheral organs at risk(ORA) and guaranteeing therapeutic effects. With the acceptable acute and long-term toxicity, CSI using HT in intracranial germinoma patients can be a safe and alternative mode.
文摘Whole brain radiotherapy (WBRT) remains the standard management of breast cancer patients with brain metastases, allowing for symptomatic improvement and good local control in most patients. However, its results remain suboptimal in terms of both efficacy and toxicity. In highly selected breast cancer patients, stereotaxic radiotherapy demonstrates a very good local control with a low toxicity. With the purpose of improving the efficacy/toxicity ratio, we report the association of integrated boost with WBRT in a breast cancer patient with brain metastases. Two and a half years after completion of helical tomotherapy (HT), the patient experienced clinical and radiological complete remission of her brain disease. No delayed toxicity occurred and the patient kept her hair without need of radiosurgical procedure. The HT provided a high dosimetric homogeneity, delivering integrated radiation boosts, and avoiding critical structures involved in long-term neurological toxicity. Further assessment is required and recruitment of breast cancer patients into clinical trials is encouraged.
文摘Radiotherapy for locally advanced pancreatic cancer is technically difficult and frequently associated with high-grade digestive toxicity.Helical tomotherapy(HT)is a new irradiation modality that combines megavoltage computed tomography imaging for patient positioning with intensity-modulated fan-beam radiotherapy.Its recent availability opens new fields of exploration for pancreatic radiotherapy as a result of its ability to tailor very well-defined dose distributions around the target volumes.Here,we report the use of HT in two patients with locally advanced pancreatic cancer. Doses to the bowel,kidneys and liver were reduced significantly,which allowed for excellent treatment tolerance without any high-grade adverse effects in either patient.
文摘Purpose: Craniospinal axis irradiation (CSI) is a method of treating various central nervous system malignancies. The large target volume typically includes entire spinal cord and whole brain. Dosimetric comparison was performed between tomotherapy, volumetric modulated arc therapy (VMAT), and 3D conformal radiation therapy (3D-CRT) for CSI. Methods and Materials: Five (n = 5) CSI patients were planned using 3D-CRT, VMAT, and tomotherapy (normalized such that 95% of PTV received at least 23.4 Gy in 13 fractions). Plans were compared using PTV conformity number (CN) and homogeneity index (HI), normal tissue (NT) dose statistics, integral dose, and treatment time. Results: On average, tomotherapy plans showed higher CN (0.932 vs. 0.860 and 0.672 for SmartArc and 3D-CRT). In terms of HI, VMAT plans consistently showed better dose homogeneity (1.07 vs. 1.15 and 1.13 for tomotherapy and 3D-CRT). SmartArc delivered lower maximum dose for majority of NT, but higher mean dose. 3D-CRT plans delivered higher maximum dose but lower mean dose to NT. Conclusions: SmartArc treatments achieved better PTV homogeneity and reduced maximum dose to NT. Tomotherapy showed better target conformity, but 3D-CRT was shown to reduce mean dose to NT. Integral doses were similar between treatment modalities, but tomotherapy treatment times were much longer.
文摘Purpose: To evaluate the accuracy of deformable image registration (DIR) between the planning kVCT (pCT) and the daily MVCT combined with the histogram matching (HM) algorithm, and evaluate the deformable dose accumulation using a suggested method for adaptive radiotherapy with Helical Tomotharapy (HT). Methods: For five prostate cancer patients (76 Gy/38 Fr) treated with HT in our institution, seven MVCT series (a total of 35 series) acquired weekly were investigated. First, to minimize the effect of different HU values between pCT and MVCT, this image-processing method adjusts HU values between pCT and MVCT images by using image cumulative histograms of HU values, generating an HM-MVCT. Then, the DIR of the pCT to the HM-MVCT was performed, generating a deformed pCT. Finally, deformable dose accumulation was performed toward the pCT image. Results: The accuracy of DIR was significantly improved by using the HM algorithm, compared with non-HM method for several structures (p ±0.05, 0.83 ±0.06, and 0.90 ± 0.04 for the CTV, rectum, and bladder, respectively, while that of the HM method was 0.81 ±0.06, 0.81 ±0.04, and 0.92 ±0.06, respectively. For the deformable dose accumulation, some difference was observed between the two methods, particularly for the small calculated regions, such as rectum V60 and V70. Conclusion: Adapting the HM method can improve the accuracy of DIR. Furthermore, dose calculation using the deformed pCT using HM methods can be an effective tool for adaptive radiotherapy.
文摘To evaluate the efficacy and feasibility of external beam radiotherapy(EBRT) for duodenal adenocarcinoma in an 84-year-old female who underwent EBRT(2.2 Gy/d for a total dose of 46.2 Gy) using helical tomotherapy(HT). Toxicity was evaluated on the National Cancer Institute's common toxicity criteria(CTCAE 3.0). The patient completed the treatment without G3-G4 toxicity. After 22-mo follow-up, she is alive and well, in complete remission with no late side effects. HT seems to be feasible and effective for duodenal adenocarcinoma in old to very old patients.
文摘Purpose: Nasal lymphoma created dosimetric challenges in radiotherapy due to the complex anatomical structures. This study was to evaluate the efficacy and toxicity of helical Tomotherapy (HT) in the treatment of nasal NK/T-cell lymphoma (NKTCL) patients. Methods and Materials: Between August 2008 and April 2013, a total of 25 NKTCL patients were treated with HT in our department;Among them, three patients have not received chemotherapy, one patient has received concurrent chemo-radiation with CHOP plus L-ASP, two patients have received the sequential chemotherapy regimen following irradiation, and all the others have received 1 - 2 cycles of induction chemotherapy followed by irradiation and then with sequential chemotherapy. CHOP-L with 1 - 7 cycles (median: 4 cycles) was utilized as the main chemotherapy regimen. As for HT, the gross tumor volume (GTV) received target doses (TD) ranging from 50 to 56 Gy (median: 50 Gy) at 2 - 2.78 Gy per fraction;and the clinical target volume (CTV) from 36 to 50 Gy (median: 40 Gy) at 1.6 - 2 Gy per fraction. Results: For those patients who had received irradiation, thirteen achieved complete remission (CR), four partial responses (PR);four had progressive disease (PD), two were lost to follow-up, two died within one month after irradiation and were not followed. In 21 patients with follow-up records, the overall response (CR + PR) was 81.0% with the 3-year survival rate of 87.2%, and the mean survival time was 52.8 months [95% confidence interval (CI): 45.2 - 60.4 months]. After radiotherapy the majority of patients had dry mouth and taste changes in varying degrees, and a small portion of patients had compromised hearing or vision functions. No brain injury symptoms occurred during radiation radiotherapy. Conclusions: As compared with conventional three-dimensional conformal radiotherapy (3D-CRT) and intensity modulated radiation therapy (IMRT) performed with HT, HT appears to have more favorable efficacy and toxicity profiles in the treatment of NKTCL. Further systematic and randomized clinical research is under investigation.
基金financially supported by the National Key R&D Projects(No.2021YFB3702000)the Regional Company Projects in Ansteel Beijing Research Institute(No.2022BJB07GF&No.2022BJB-13GF)。
文摘Electromagnetic stirring is one of the widely applied techniques to modify the quality of casting billets.Different from conventional rotate stirring,the helical stirring is more professional in assisting multi-dimensional flow of molten metal and eliminating solidification defects.In this study,the single-winding helical stirring(SWHS)was introduced,offering advantages such as smaller volume and lower electromagnetic shielding compared to traditional helical stirring methods.Following a comprehensive numerical simulation,the stirring parameters of SWHS were adjusted to yoke inclination angle of 43°and frequency of 12 Hz.The higher electromagnetic force and flow velocity in drawing direction,as well as the lower temperature gradient induced by the SWHS,are positive factors for homogeneous solidification of billet.The experimental results on Al-8%Si alloy and 0.4%C-1.1%Mn steel demonstrate that compared to rotate stirring,the SWHS process can induce better billet quality and is more effective in accelerating the equiaxed expansion and reducing element segregation.The SWHS process can enhance the equiaxed ratio of the billet by 58.3%and reduce segregation degree of carbon element by 10.97%.Consequently,SWHS holds great promise as a potential approach for improving the quality of continuous casting billets.
基金financially supported by the National Natural Science Foundation of China (Grant Nos.51890913 and 51879183)the China Harbour Engineering Company (Grant No.2018-ZJKJ-01)+2 种基金the China Scholarship Councilthe State Key Laboratory of Hydraulic Engineering Simulation and Safety,Tianjin University (Grant No.HESS-2019)the State Key Laboratory of Coastal and Offshore Engineering,Dalian University of Technology (Grant No.LP2120)。
文摘Helical anchor is a kind of novel foundation for floating offshore wind turbines,which should be subjected to combined tensile loading caused by wind,wave and current.However,the research about the capacity of helical anchor was mainly examined under uniaxial loading and scarcely explored under combined loading.In this study,three-dimensional finite element limit analysis is adopted to assess the bearing capacities of single-plate rigid helical anchors with different ratios of helix to shaft diameter,D_(H)/D_(S) and embedment ratios L/D_(S).Result shows that the vertical,horizontal and moment bearing capacities increase with increasing D_(H)/D_(S) and L/D_(S).The normalized V-H failure envelopes expands with increasing L/D_(S),while the normalized V-M failure envelopes tend to contract with the increase of D_(H)/D_(S).With increasing D_(H)/D_(S) or decreasing L/D_(S),the normalized H-M failure envelopes expand when the horizontal and moment loading act in the same direction and contract when they act in the opposite direction.The effect of D_(H)/D_(S) and L/D_(S) on the shape of H-M failure envelope become insignificant when L/D_(S)≥4.A series of failure mechanisms under different loading conditions were observed and can be used to explain the trend.Besides,a series of approximate expressions were proposed to fit the uniaxial bearing capacities and the failure envelopes.
文摘In this paper, the problem of finding exact solutions to the magnetohydrodynamic(MHD) equations in the presence of incompressible mass flows with helical symmetry is considered. For ideal flows, a similarity reduction method is used to obtain exact solutions for several MHD flows with nonlinear variable Mach number. For resistive flows parallel to a magnetic field, the governing equilibrium equation is derived. The MHD equilibrium state of a helically symmetric incompressible flow is governed by a second-order elliptic partial differential equation(PDE) for the helical magnetic flux function. Exact solutions for the latter equation are obtained. Also, the equilibrium equations of a gravitating plasma with incompressible flow are derived.
文摘The aim of this study is the numerical analysis of the melting process of the phase change material(PCM)in a spiral coil.The space between the inner tube and outer shell is filled with RT-50 as PCM.Moreover,the hybrid nanofluid(with a carbon component)flows through the inner tube.The novelty of this work is to use different configurations of fin and different percentage of hybrid nanoparticles(SWCNTs-Cu O)on the PCM melting process.In the numerical model created by ANSYS-Fluent,the effect of various inlet temperatures is investigated.The results indicate that the extended surface created by extra fin has a dominant effect on melting time,so by adding the third fin,the melting time is reduced by 39.24%.The next most influential factor in PCM melting is the inlet temperature of the working fluid,so that 10°C increment of temperature result in the PCM melting time decreased by 35.41%.
文摘The goal of this research is to look at multi-target optimization of a two-stage helical gearbox in order to determine the best key design elements for reducing gearbox height and enhancing gearbox efficiency.To do this,the method known as Taguchi and GRA(Grey Relation Analysis)were used in two stages to address the problem.The single-objective optimization problem was addressed first to close the gap between variable levels,and then the multi-objective optimization problem was solved to determine the best primary design variables.The first and second stage CWFWs(Coefficients of Wheel Face Width),ACS(Permissible Contact Stresses),and first stage gear ratio were also calculated.The study’s findings were utilized to identify the best values for five critical design aspects of a two-stage helical gearbox.
