Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA.
Department of Radiation Oncology Physics and Technology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan Shandong, China.
Med Phys. 2024 Aug;51(8):5738-5745. doi: 10.1002/mp.17121. Epub 2024 May 19.
Ultra-high-dose-rate (UHDR) electron beams have been commonly utilized in FLASH studies and the translation of FLASH Radiotherapy (RT) to the clinic. The EDGE diode detector has potential use for UHDR dosimetry albeit with a beam energy dependency observed.
The purpose is to present the electron beam response for an EDGE detector in dependence on beam energy, to characterize the EDGE detector's response under UHDR conditions, and to validate correction factors derived from the first detailed Monte Carlo model of the EDGE diode against measurements, particularly under UHDR conditions.
Percentage depth doses (PDDs) for the UHDR Mobetron were measured with both EDGE detectors and films. A detailed Monte Carlo (MC) model of the EDGE detector has been configured according to the blueprint provided by the manufacturer under an NDA agreement. Water/silicon dose ratios of EDGE detector for a series of mono-energetic electron beams have been calculated. The dependence of the water/silicon dose ratio on depth for a FLASH relevant electron beam was also studied. An analytical approach for the correction of PDD measured with EDGE detectors was established.
Water/silicon dose ratio decreased with decreasing electron beam energy. For the Mobetron 9 MeV UHDR electron beam, the ratio decreased from 1.09 to 1.03 in the build-up region, maintained in range of 0.98-1.02 at the fall-off region and raised to a plateau in value of 1.08 at the tail. By applying the corrections, good agreement between the PDDs measured by the EDGE detector and those measured with film was achieved.
Electron beam response of an UHDR capable EDGE detector was derived from first principles utilizing a sophisticated MC model. An analytical approach was validated for the PDDs of UHDR electron beams. The results demonstrated the capability of EDGE detector in measuring PDDs of UHDR electron beams.
超高剂量率（UHDR）电子束已广泛应用于 FLASH 研究，并将 FLASH 放疗（RT）转化为临床应用。EDGE 二极管探测器具有用于 UHDR 剂量测量的潜力，尽管观察到与束能有关的依赖性。
本研究旨在展示 EDGE 探测器对电子束能量的响应，描述 EDGE 探测器在 UHDR 条件下的响应特性，并验证源自 EDGE 二极管第一个详细蒙特卡罗模型的校正因子与测量值的一致性，特别是在 UHDR 条件下。
使用 EDGE 探测器和胶片测量了超高剂量率 Mobetron 的百分深度剂量（PDD）。根据 NDA 协议，根据制造商提供的蓝图，为 EDGE 探测器配置了详细的蒙特卡罗（MC）模型。计算了 EDGE 探测器在一系列单能电子束下的水/硅剂量比。还研究了 FLASH 相关电子束下水/硅剂量比随深度的变化。建立了一种用于校正 EDGE 探测器测量的 PDD 的解析方法。
水/硅剂量比随电子束能量的降低而降低。对于 Mobetron 9 MeV UHDR 电子束，在 buildup 区域，该比值从 1.09 降低至 1.03，在下降区域保持在 0.98-1.02 之间，在尾部升高至 1.08 的平台值。通过应用校正，EDGE 探测器测量的 PDD 与胶片测量的 PDD 之间达到了良好的一致性。
利用先进的 MC 模型，从第一性原理推导出了 UHDR 能力 EDGE 探测器的电子束响应。验证了一种用于 UHDR 电子束 PDD 的解析方法。结果表明 EDGE 探测器具有测量 UHDR 电子束 PDD 的能力。
