针对核医学发展需求,本研究提出将直线加速器机房改建为回旋加速器机房的解决方案。通过理论计算与MCNP(Monte Carlo N-particle transport code)模拟,评估原重混凝土机房(厚度1.2~2.6 m)对γ射线的屏蔽效能,并针对中子辐射提出内壁增...针对核医学发展需求,本研究提出将直线加速器机房改建为回旋加速器机房的解决方案。通过理论计算与MCNP(Monte Carlo N-particle transport code)模拟,评估原重混凝土机房(厚度1.2~2.6 m)对γ射线的屏蔽效能,并针对中子辐射提出内壁增设含硼聚乙烯(24~48 cm)的优化方案。结果表明:原有混凝土结构满足γ防护要求,选择屏蔽中子效率高、次生γ增量少的含硼聚乙烯,经模拟验证剂量率水平较低;采用聚乙烯慢化层与含硼聚乙烯(11%)吸收层组合,有效避免铁矿石骨料的中子活化风险;该方案施工难度低,成本可控,能够实现医疗设施高效再利用。本研究为同类改造提供技术参考,符合我国核医学高质量发展政策需求。展开更多
Van der Waals(vdW)heterostructures have attracted much attention due to their distinctive optical,electrical,and thermal properties,demonstrating promising potential in areas such as photocatalysis,ultrafast photonics...Van der Waals(vdW)heterostructures have attracted much attention due to their distinctive optical,electrical,and thermal properties,demonstrating promising potential in areas such as photocatalysis,ultrafast photonics,and free electron radiation devices.Particularly,they are promising platforms for studying thermionic emission.It is illustrated that using vdW heterostructure-based thermionic emission can enhance heat transfer in vacuum devices.As a proof of concept,the approach is demonstrated to offer a promising solution for the long-standing overheating issue in X-ray tubes.Specifically,it is shown that the saturated target temperature of a 2000 W X-ray tube can be reduced from around 1200℃ to 490℃.Additionally,it is also demonstrated that by reducing the height of the Schottky barrier formed in the vdW heterostructures,the thermionic cooling performance can be enhanced.The findings pave the way for the development of high-power X-ray tubes.展开更多
1故障一故障现象:治疗过程中报错“PCP communication error”,重启后停留在初始化状态。故障分析:PCP为机器外壳前部上方左右2个12寸显示屏,该报错一般为通信故障。单个PCP故障时,首先检查输入电源,确认电源线接触是否良好,输入电压是...1故障一故障现象:治疗过程中报错“PCP communication error”,重启后停留在初始化状态。故障分析:PCP为机器外壳前部上方左右2个12寸显示屏,该报错一般为通信故障。单个PCP故障时,首先检查输入电源,确认电源线接触是否良好,输入电压是否正常,并进行针对性处理。其次检查网络通信,确认IP地址和TOMO内部电脑主机在同一网段,利用service PC通过ping指令确认通信是否正常。显示屏本身故障以及PCP软件丢失均是产生故障的因素,通过维修显示屏或重刷软件可解决该故障。两个PCP同时故障时,除了上述单个故障排除的方法以外,需要检查机器前外壳和显示屏之间的72芯排线各个针脚有无折损、氧化,并用万用表检测两侧针脚通信是否良好。该排线由于长期暴露在空气中,受机房环境影响较大,容易氧化导致接触不良,引起故障,排查故障时需重点关注。展开更多
文摘针对核医学发展需求,本研究提出将直线加速器机房改建为回旋加速器机房的解决方案。通过理论计算与MCNP(Monte Carlo N-particle transport code)模拟,评估原重混凝土机房(厚度1.2~2.6 m)对γ射线的屏蔽效能,并针对中子辐射提出内壁增设含硼聚乙烯(24~48 cm)的优化方案。结果表明:原有混凝土结构满足γ防护要求,选择屏蔽中子效率高、次生γ增量少的含硼聚乙烯,经模拟验证剂量率水平较低;采用聚乙烯慢化层与含硼聚乙烯(11%)吸收层组合,有效避免铁矿石骨料的中子活化风险;该方案施工难度低,成本可控,能够实现医疗设施高效再利用。本研究为同类改造提供技术参考,符合我国核医学高质量发展政策需求。
基金supported by National Natural Science Foundation of China(61921002 and 92163204)。
文摘Van der Waals(vdW)heterostructures have attracted much attention due to their distinctive optical,electrical,and thermal properties,demonstrating promising potential in areas such as photocatalysis,ultrafast photonics,and free electron radiation devices.Particularly,they are promising platforms for studying thermionic emission.It is illustrated that using vdW heterostructure-based thermionic emission can enhance heat transfer in vacuum devices.As a proof of concept,the approach is demonstrated to offer a promising solution for the long-standing overheating issue in X-ray tubes.Specifically,it is shown that the saturated target temperature of a 2000 W X-ray tube can be reduced from around 1200℃ to 490℃.Additionally,it is also demonstrated that by reducing the height of the Schottky barrier formed in the vdW heterostructures,the thermionic cooling performance can be enhanced.The findings pave the way for the development of high-power X-ray tubes.
文摘1故障一故障现象:治疗过程中报错“PCP communication error”,重启后停留在初始化状态。故障分析:PCP为机器外壳前部上方左右2个12寸显示屏,该报错一般为通信故障。单个PCP故障时,首先检查输入电源,确认电源线接触是否良好,输入电压是否正常,并进行针对性处理。其次检查网络通信,确认IP地址和TOMO内部电脑主机在同一网段,利用service PC通过ping指令确认通信是否正常。显示屏本身故障以及PCP软件丢失均是产生故障的因素,通过维修显示屏或重刷软件可解决该故障。两个PCP同时故障时,除了上述单个故障排除的方法以外,需要检查机器前外壳和显示屏之间的72芯排线各个针脚有无折损、氧化,并用万用表检测两侧针脚通信是否良好。该排线由于长期暴露在空气中,受机房环境影响较大,容易氧化导致接触不良,引起故障,排查故障时需重点关注。
