Background: In linear accelerators, the treatment field’s uniform intensity is achieved by including a flattening filter in the beam. However, to produce more conformal dose distributions, contemporary radiotherapy p...Background: In linear accelerators, the treatment field’s uniform intensity is achieved by including a flattening filter in the beam. However, to produce more conformal dose distributions, contemporary radiotherapy practice now frequently uses fluence and aperture modifying techniques, such as volumetric modulated arc therapy. In these circumstances, the flattening filter in the beam manufacturing process is no longer required. It is therefore necessary to compare the monitor units of 6 MV and flattening filter free plans and how it influences the gamma pass rates to determine which is best for treating cervical cancer with pelvic lymph node metastasis. Methods: VMAT plans for fifteen patients with cervical cancer with pathological pelvic lymph node metastasis were included in this study. Each patient had two VMAT plans using conventional 6 MV beam with flattening filter and one with flattening filter free beam (FFF). The VMAT plans were made using two arcs, and then recalculated to give the planned dose distribution to the detectors in a Delta4 phantom. The VMAT plans were irradiated on the Delta4 phantom using an Elekta linear accelerator (6 MV). Results: The mean monitor unit for the 6 MV plans was 506.3 MU and a standard deviation of 48.6 while that of the FFF plans had a mean MU of 701.5 with a standard deviation of 87.6. The total monitor units (MUs) for the FFF plans were significantly greater than the 6 MV plans (p = 6.1 × 10<sup>-5</sup>). Conclusion: Flattening filter free (FFF) plans require more numbers of monitor units in comparison to conventional 6 MV filtered beams for external radiation of cervical cancer with pelvic lymph nodes involvement.展开更多
Intensity modulated radiation therapy (IMRT) is a highly accurate technique that is usually implemented in either dynamic or step-and-shoot fashion with many segments each having low monitor units (MUs). The present s...Intensity modulated radiation therapy (IMRT) is a highly accurate technique that is usually implemented in either dynamic or step-and-shoot fashion with many segments each having low monitor units (MUs). The present study evaluated the effects of beam startup characteristics on the dose delivery accuracy for each segment at low MUs for step-and-shoot IMRT with an Elekta Precise accelerator at the highest dose rates. We used a two-dimensional semi-conductor detector for the dose measurements. The field size of each segment was assumed to be 20 ×20 cm2 and each segment was set to deliver 1 - 10 MUs. Our results show a variation in dose delivery accuracy between segments for the same IMRT beam, which can be attributed to the beam startup characteristics. This variability is attributed to the changes in the transient changes in the temperatures of the electron gun filament and the magnetron. That is, the transient increase in the temperature of the filament leads to increasing doses with time and that of the magnetron leads to decreasing doses with time during the first few MUs.展开更多
The stability of delivery of low monitor unit (MU) setting is important especially for step-and-shoot intensity-modulated radiotherapy (IMRT), because the nature of the technique is inherent to repeat beam on/off acco...The stability of delivery of low monitor unit (MU) setting is important especially for step-and-shoot intensity-modulated radiotherapy (IMRT), because the nature of the technique is inherent to repeat beam on/off according to the number of the segments. This study evaluates the dose linearity and profile flatness/symmetry under low MU settings for Vero4DRT, a new linear-accelerator based irradiation system that currently implements step-and-shoot IMRT. To evaluate the dose linearity and flatness/symmetry, the point doses and beam profiles were measured as functions of MU and dose rates. The accuracy of dose delivery depended on the dose rate. Under all dose rates, the dose was linear within 1% above 5 MU and within 2% above 3 MU. The beam symmetry was degraded in-line compared with crossline, although both profiles were symmetric within 2% at all dose settings. The profile flatness was also within 2% above 5 MU at any dose rate and showed no significant variation among the low MU settings. To ensure stable beam delivery without increasing the treatment time of Vero4DRT, we recommend a delivery of 5 MU per segment at a dose rate of 500 MU/min.展开更多
In this paper, a network-based monitoring unit for condition monitoring andfault diagnosis of rotating machinery is designed and implemented. With the technology of DSP(Digital signal processing) , TCP/IP, and simulta...In this paper, a network-based monitoring unit for condition monitoring andfault diagnosis of rotating machinery is designed and implemented. With the technology of DSP(Digital signal processing) , TCP/IP, and simultaneous acquisition, a mechanism of multi-process andinter-process communication, the integrating problem of signal acquisition, the data dynamicmanagement and network-based configuration in the embedded condition monitoring system is solved. Itoffers the input function of monitoring information for network-based condition monitoring and afault diagnosis system.展开更多
ZJZ-2 system has the following functions: (1) Real-time on-line sampling and FFT analysis (32 channel); (2) Data aquisition, analysis and storage during start-up and shut-down; (3) Alarming, emergency recognition and ...ZJZ-2 system has the following functions: (1) Real-time on-line sampling and FFT analysis (32 channel); (2) Data aquisition, analysis and storage during start-up and shut-down; (3) Alarming, emergency recognition and fault retrieval; (4) Data aquisition, analysis and storage during daily operation; (5) Recall of historic data; (6) Output of routine reports and tables; (7) Analysis of vibration behaviour: Bode plot, polar plot, spectrum, cascade, waveform, shaft orbit, trend, etc;展开更多
目的:分析重症患者抗癫痫药物(antiepileptic drugs,AEDs)用药情况、治疗药物监测(therapeutic drug monitoring,TDM)结果的影响因素,为重症患者AEDs临床合理用药提供参考。方法:系统回顾分析哈尔滨医科大学附属第一医院2019-2024年入...目的:分析重症患者抗癫痫药物(antiepileptic drugs,AEDs)用药情况、治疗药物监测(therapeutic drug monitoring,TDM)结果的影响因素,为重症患者AEDs临床合理用药提供参考。方法:系统回顾分析哈尔滨医科大学附属第一医院2019-2024年入住重症监护病房(intensive care unit,ICU)应用AEDs的559例患者的治疗信息,统计分析AEDs使用情况、TDM结果及影响因素。结果:ICU患者最常用的AED为丙戊酸钠(97.67%),其次为左乙拉西坦(20.57%);多数为单独用药(74.24%),且单用丙戊酸钠的比例最高(72.27%);最常用的联合方案为丙戊酸钠+左乙拉西坦;首次TDM达窗率较低(49.53%),剂量调整后达窗率显著提高至64.34%(P<0.05);给药方式、性别均可影响丙戊酸血药浓度(C)和血药浓度/剂量(C/D)(P<0.05),静脉给药,尤其是静脉持续给药后的C及C/D均高于非静脉给药(P<0.05)。结论:需强化ICU患者AEDs的TDM,重点关注给药方式及性别等因素对血药浓度的影响,依据TDM结果实施个体化用药,以提升治疗效果,降低不良反应。展开更多
针对离散制造车间中人工记录生产数据无法满足生产制造任务及时安排的问题,通过分析机床电机电流信号实现机床运行状态监测,以提高车间智能化水平。基于机床电机电流信号易采集、低成本的特性,提出一种能够准确识别机床组中运行机床的...针对离散制造车间中人工记录生产数据无法满足生产制造任务及时安排的问题,通过分析机床电机电流信号实现机床运行状态监测,以提高车间智能化水平。基于机床电机电流信号易采集、低成本的特性,提出一种能够准确识别机床组中运行机床的监测新方法。新方法将灰狼优化算法(Grey Wolf Optimization,GWO)与变分模态分解(Variational Mode Decomposition,VMD)相结合,对多机床复合电机电流信号进行频谱重构,强化特征频段信息,再搭建CNN-GRU神经网络模型完成运动状态分类。结果表明,此频谱重构方法能够有效强化电流信号中的微弱特征频段,显著提升模型识别效果,不仅识别准确率达到98%以上,且具有一定通用性。展开更多
文摘Background: In linear accelerators, the treatment field’s uniform intensity is achieved by including a flattening filter in the beam. However, to produce more conformal dose distributions, contemporary radiotherapy practice now frequently uses fluence and aperture modifying techniques, such as volumetric modulated arc therapy. In these circumstances, the flattening filter in the beam manufacturing process is no longer required. It is therefore necessary to compare the monitor units of 6 MV and flattening filter free plans and how it influences the gamma pass rates to determine which is best for treating cervical cancer with pelvic lymph node metastasis. Methods: VMAT plans for fifteen patients with cervical cancer with pathological pelvic lymph node metastasis were included in this study. Each patient had two VMAT plans using conventional 6 MV beam with flattening filter and one with flattening filter free beam (FFF). The VMAT plans were made using two arcs, and then recalculated to give the planned dose distribution to the detectors in a Delta4 phantom. The VMAT plans were irradiated on the Delta4 phantom using an Elekta linear accelerator (6 MV). Results: The mean monitor unit for the 6 MV plans was 506.3 MU and a standard deviation of 48.6 while that of the FFF plans had a mean MU of 701.5 with a standard deviation of 87.6. The total monitor units (MUs) for the FFF plans were significantly greater than the 6 MV plans (p = 6.1 × 10<sup>-5</sup>). Conclusion: Flattening filter free (FFF) plans require more numbers of monitor units in comparison to conventional 6 MV filtered beams for external radiation of cervical cancer with pelvic lymph nodes involvement.
文摘Intensity modulated radiation therapy (IMRT) is a highly accurate technique that is usually implemented in either dynamic or step-and-shoot fashion with many segments each having low monitor units (MUs). The present study evaluated the effects of beam startup characteristics on the dose delivery accuracy for each segment at low MUs for step-and-shoot IMRT with an Elekta Precise accelerator at the highest dose rates. We used a two-dimensional semi-conductor detector for the dose measurements. The field size of each segment was assumed to be 20 ×20 cm2 and each segment was set to deliver 1 - 10 MUs. Our results show a variation in dose delivery accuracy between segments for the same IMRT beam, which can be attributed to the beam startup characteristics. This variability is attributed to the changes in the transient changes in the temperatures of the electron gun filament and the magnetron. That is, the transient increase in the temperature of the filament leads to increasing doses with time and that of the magnetron leads to decreasing doses with time during the first few MUs.
文摘The stability of delivery of low monitor unit (MU) setting is important especially for step-and-shoot intensity-modulated radiotherapy (IMRT), because the nature of the technique is inherent to repeat beam on/off according to the number of the segments. This study evaluates the dose linearity and profile flatness/symmetry under low MU settings for Vero4DRT, a new linear-accelerator based irradiation system that currently implements step-and-shoot IMRT. To evaluate the dose linearity and flatness/symmetry, the point doses and beam profiles were measured as functions of MU and dose rates. The accuracy of dose delivery depended on the dose rate. Under all dose rates, the dose was linear within 1% above 5 MU and within 2% above 3 MU. The beam symmetry was degraded in-line compared with crossline, although both profiles were symmetric within 2% at all dose settings. The profile flatness was also within 2% above 5 MU at any dose rate and showed no significant variation among the low MU settings. To ensure stable beam delivery without increasing the treatment time of Vero4DRT, we recommend a delivery of 5 MU per segment at a dose rate of 500 MU/min.
文摘In this paper, a network-based monitoring unit for condition monitoring andfault diagnosis of rotating machinery is designed and implemented. With the technology of DSP(Digital signal processing) , TCP/IP, and simultaneous acquisition, a mechanism of multi-process andinter-process communication, the integrating problem of signal acquisition, the data dynamicmanagement and network-based configuration in the embedded condition monitoring system is solved. Itoffers the input function of monitoring information for network-based condition monitoring and afault diagnosis system.
文摘ZJZ-2 system has the following functions: (1) Real-time on-line sampling and FFT analysis (32 channel); (2) Data aquisition, analysis and storage during start-up and shut-down; (3) Alarming, emergency recognition and fault retrieval; (4) Data aquisition, analysis and storage during daily operation; (5) Recall of historic data; (6) Output of routine reports and tables; (7) Analysis of vibration behaviour: Bode plot, polar plot, spectrum, cascade, waveform, shaft orbit, trend, etc;
文摘目的:分析重症患者抗癫痫药物(antiepileptic drugs,AEDs)用药情况、治疗药物监测(therapeutic drug monitoring,TDM)结果的影响因素,为重症患者AEDs临床合理用药提供参考。方法:系统回顾分析哈尔滨医科大学附属第一医院2019-2024年入住重症监护病房(intensive care unit,ICU)应用AEDs的559例患者的治疗信息,统计分析AEDs使用情况、TDM结果及影响因素。结果:ICU患者最常用的AED为丙戊酸钠(97.67%),其次为左乙拉西坦(20.57%);多数为单独用药(74.24%),且单用丙戊酸钠的比例最高(72.27%);最常用的联合方案为丙戊酸钠+左乙拉西坦;首次TDM达窗率较低(49.53%),剂量调整后达窗率显著提高至64.34%(P<0.05);给药方式、性别均可影响丙戊酸血药浓度(C)和血药浓度/剂量(C/D)(P<0.05),静脉给药,尤其是静脉持续给药后的C及C/D均高于非静脉给药(P<0.05)。结论:需强化ICU患者AEDs的TDM,重点关注给药方式及性别等因素对血药浓度的影响,依据TDM结果实施个体化用药,以提升治疗效果,降低不良反应。
文摘针对离散制造车间中人工记录生产数据无法满足生产制造任务及时安排的问题,通过分析机床电机电流信号实现机床运行状态监测,以提高车间智能化水平。基于机床电机电流信号易采集、低成本的特性,提出一种能够准确识别机床组中运行机床的监测新方法。新方法将灰狼优化算法(Grey Wolf Optimization,GWO)与变分模态分解(Variational Mode Decomposition,VMD)相结合,对多机床复合电机电流信号进行频谱重构,强化特征频段信息,再搭建CNN-GRU神经网络模型完成运动状态分类。结果表明,此频谱重构方法能够有效强化电流信号中的微弱特征频段,显著提升模型识别效果,不仅识别准确率达到98%以上,且具有一定通用性。
