PDF(Pubmed)
Abstract：
UNASSIGNED: We have previously adapted a clinical linear accelerator (Elekta Precise, Elekta AB) for ultra-high dose rate (UHDR) electron delivery. To enhance reliability in future clinical FLASH radiotherapy trials, the aim of this study was to introduce and evaluate an upgraded beam control system and beam tuning process for safe and precise UHDR delivery.
UNASSIGNED: The beam control system is designed to interrupt the beam based on 1) a preset number of monitor units (MUs) measured by a monitor detector, 2) a preset number of pulses measured by a pulse-counting diode, or 3) a preset delivery time. For UHDR delivery, an optocoupler facilitates external control of the accelerator\'s thyratron trigger pulses. A beam tuning process was established to maximize the output. We assessed the stability of the delivery, and the independent interruption capabilities of the three systems (monitor detector, pulse counter, and timer). Additionally, we explored a novel approach to enhance dosimetric precision in the delivery by synchronizing the trigger pulse with the charging cycle of the pulse forming network (PFN).
UNASSIGNED: Improved beam tuning of gun current and magnetron frequency resulted in average dose rates at the dose maximum at isocenter distance of >160 Gy/s or >200 Gy/s, with or without an external monitor chamber in the beam path, respectively. The delivery showed a good repeatability (standard deviation (SD) in total film dose of 2.2%) and reproducibility (SD in film dose of 2.6%). The estimated variation in DPP resulted in an SD of 1.7%. The output in the initial pulse depended on the PFN delay time. Over the course of 50 measurements employing PFN synchronization, the absolute percentage error between the delivered number of MUs calculated by the monitor detector and the preset MUs was 0.8 ± 0.6% (mean ± SD).
UNASSIGNED: We present an upgraded beam control system and beam tuning process for safe and stable UHDR electron delivery of hundreds of Gy/s at isocenter distance at a clinical linac. The system can interrupt the beam based on monitor units and utilize PFN synchronization for improved dosimetric precision in the dose delivery, representing an important advancement toward reliable clinical FLASH trials.
UNASSIGNED: The beam control system is designed to interrupt the beam based on 1) a preset number of monitor units (MUs) measured by a monitor detector, 2) a preset number of pulses measured by a pulse-counting diode, or 3) a preset delivery time. For UHDR delivery, an optocoupler facilitates external control of the accelerator\'s thyratron trigger pulses. A beam tuning process was established to maximize the output. We assessed the stability of the delivery, and the independent interruption capabilities of the three systems (monitor detector, pulse counter, and timer). Additionally, we explored a novel approach to enhance dosimetric precision in the delivery by synchronizing the trigger pulse with the charging cycle of the pulse forming network (PFN).
UNASSIGNED: Improved beam tuning of gun current and magnetron frequency resulted in average dose rates at the dose maximum at isocenter distance of >160 Gy/s or >200 Gy/s, with or without an external monitor chamber in the beam path, respectively. The delivery showed a good repeatability (standard deviation (SD) in total film dose of 2.2%) and reproducibility (SD in film dose of 2.6%). The estimated variation in DPP resulted in an SD of 1.7%. The output in the initial pulse depended on the PFN delay time. Over the course of 50 measurements employing PFN synchronization, the absolute percentage error between the delivered number of MUs calculated by the monitor detector and the preset MUs was 0.8 ± 0.6% (mean ± SD).
UNASSIGNED: We present an upgraded beam control system and beam tuning process for safe and stable UHDR electron delivery of hundreds of Gy/s at isocenter distance at a clinical linac. The system can interrupt the beam based on monitor units and utilize PFN synchronization for improved dosimetric precision in the dose delivery, representing an important advancement toward reliable clinical FLASH trials.
摘要：
■我们以前已经适应了临床直线加速器（ElektaPrecise，ElektaAB）用于超高剂量率（UHDR）电子传输。为了提高未来临床FLASH放射治疗试验的可靠性，这项研究的目的是介绍和评估升级的光束控制系统和光束调谐过程，以实现安全和精确的UHDR传输。
■光束控制系统设计为根据1）由监视器检测器测量的预设数量的监视器单元（MU）来中断光束，2）由脉冲计数二极管测量的预设数量的脉冲，或3)预设的交货时间。对于UHDR交付，光耦合器有助于加速器的闸流管触发脉冲的外部控制。建立了光束调谐过程以最大化输出。我们评估了交货的稳定性，以及三个系统的独立中断能力(监控探测器，脉冲计数器,和计时器）。此外,我们探索了一种新的方法，通过同步触发脉冲与脉冲形成网络（PFN）的充电周期来提高剂量精度。
■改进了喷枪电流和磁控管频率的光束调谐，导致等中心距离>160Gy/s或>200Gy/s时的最大剂量平均剂量率，在光路中有或没有外部监视器室，分别。递送显示出良好的可重复性(总胶片剂量的标准偏差(SD)为2.2%)和再现性(胶片剂量的SD为2.6%)。DPP的估计变化导致1.7%的SD。初始脉冲中的输出取决于PFN延迟时间。在50次采用PFN同步的测量过程中，监测检测器计算的已递送MU数量与预设MU之间的绝对百分比误差为0.8±0.6%(平均值±SD)。
■我们提出了一种升级的束控制系统和束调谐过程，用于在临床直线加速器上以等中心距离安全，稳定地进行数百Gy/s的UHDR电子输送。该系统可以基于监测单元中断波束，并利用PFN同步来提高剂量输送中的剂量精度。代表着可靠的临床FLASH试验的重要进展。
■光束控制系统设计为根据1）由监视器检测器测量的预设数量的监视器单元（MU）来中断光束，2）由脉冲计数二极管测量的预设数量的脉冲，或3)预设的交货时间。对于UHDR交付，光耦合器有助于加速器的闸流管触发脉冲的外部控制。建立了光束调谐过程以最大化输出。我们评估了交货的稳定性，以及三个系统的独立中断能力(监控探测器，脉冲计数器,和计时器）。此外,我们探索了一种新的方法，通过同步触发脉冲与脉冲形成网络（PFN）的充电周期来提高剂量精度。
■改进了喷枪电流和磁控管频率的光束调谐，导致等中心距离>160Gy/s或>200Gy/s时的最大剂量平均剂量率，在光路中有或没有外部监视器室，分别。递送显示出良好的可重复性(总胶片剂量的标准偏差(SD)为2.2%)和再现性(胶片剂量的SD为2.6%)。DPP的估计变化导致1.7%的SD。初始脉冲中的输出取决于PFN延迟时间。在50次采用PFN同步的测量过程中，监测检测器计算的已递送MU数量与预设MU之间的绝对百分比误差为0.8±0.6%(平均值±SD)。
■我们提出了一种升级的束控制系统和束调谐过程，用于在临床直线加速器上以等中心距离安全，稳定地进行数百Gy/s的UHDR电子输送。该系统可以基于监测单元中断波束，并利用PFN同步来提高剂量输送中的剂量精度。代表着可靠的临床FLASH试验的重要进展。
