The feasibility of estimating patient-specific dose verification results directly from linear accelerator (linac) log files has been investigated for prostate cancer patients who undergo volumetric modulated arc thera...The feasibility of estimating patient-specific dose verification results directly from linear accelerator (linac) log files has been investigated for prostate cancer patients who undergo volumetric modulated arc therapy (VMAT). Twenty-six patients who underwent VMAT in our facility were consecutively selected. VMAT plans were created using Monaco treatment planning system and were transferred to an Elekta linac. During the beam delivery, dynamic machine parameters such as positions of the multi-leaf collimator and the gantry were recorded in the log files;subsequently, root mean square (rms) values of control errors, speeds and accelerations of the above machine parameters were calculated for each delivery. Dose verification was performed for all the plans using a cylindrical phantom with diodes placed in a spiral array. The gamma index pass rates were evaluated under 3%/3 mm and 2%/2 mm criteria with a dose threshold of 10%. Subsequently, the correlation coefficients between the gamma index pass rates and each of the above rms values were calculated. Under the 2%/2 mm criteria, significant negative correlations were found between the gamma index pass rates and the rms gantry angle errors (r = 0.64, p < 0.001) as well as the pass rates and the rms gantry accelerations (r = 0.68, p < 0.001). On the other hand, the rms values of the other dynamic machine parameters did not significantly correlate with the gamma index pass rates. We suggest that the VMAT quality assurance (QA) results can be directly estimated from the log file thereby providing potential to simplify patient-specific prostate VMAT QA procedure.展开更多
对基于HTTP live streaming(简称HLS)协议的流媒体直播系统的工作原理以及结构进行了系统的介绍,利用网络数据分析仪来深入研究客户端与服务器的交互传输过程,剖析了这种技术应用于网络电视直播时所存在的视频流索引文件重复下载的冗余...对基于HTTP live streaming(简称HLS)协议的流媒体直播系统的工作原理以及结构进行了系统的介绍,利用网络数据分析仪来深入研究客户端与服务器的交互传输过程,剖析了这种技术应用于网络电视直播时所存在的视频流索引文件重复下载的冗余问题,在一定程度上造成了网络流量的浪费,降低了传输效率.针对这类问题提出了一种改善的方法——标志法,即在.m3u8文件中添加一个新标签,并通过计算推导和实验验证把改善前后的效果进行了定量分析和对比,实验结果表明该方法可有效降低流量浪费率,提高传输性能,具有较大的可行性.展开更多
文摘The feasibility of estimating patient-specific dose verification results directly from linear accelerator (linac) log files has been investigated for prostate cancer patients who undergo volumetric modulated arc therapy (VMAT). Twenty-six patients who underwent VMAT in our facility were consecutively selected. VMAT plans were created using Monaco treatment planning system and were transferred to an Elekta linac. During the beam delivery, dynamic machine parameters such as positions of the multi-leaf collimator and the gantry were recorded in the log files;subsequently, root mean square (rms) values of control errors, speeds and accelerations of the above machine parameters were calculated for each delivery. Dose verification was performed for all the plans using a cylindrical phantom with diodes placed in a spiral array. The gamma index pass rates were evaluated under 3%/3 mm and 2%/2 mm criteria with a dose threshold of 10%. Subsequently, the correlation coefficients between the gamma index pass rates and each of the above rms values were calculated. Under the 2%/2 mm criteria, significant negative correlations were found between the gamma index pass rates and the rms gantry angle errors (r = 0.64, p < 0.001) as well as the pass rates and the rms gantry accelerations (r = 0.68, p < 0.001). On the other hand, the rms values of the other dynamic machine parameters did not significantly correlate with the gamma index pass rates. We suggest that the VMAT quality assurance (QA) results can be directly estimated from the log file thereby providing potential to simplify patient-specific prostate VMAT QA procedure.
文摘对基于HTTP live streaming(简称HLS)协议的流媒体直播系统的工作原理以及结构进行了系统的介绍,利用网络数据分析仪来深入研究客户端与服务器的交互传输过程,剖析了这种技术应用于网络电视直播时所存在的视频流索引文件重复下载的冗余问题,在一定程度上造成了网络流量的浪费,降低了传输效率.针对这类问题提出了一种改善的方法——标志法,即在.m3u8文件中添加一个新标签,并通过计算推导和实验验证把改善前后的效果进行了定量分析和对比,实验结果表明该方法可有效降低流量浪费率,提高传输性能,具有较大的可行性.
