Electronic portal imaging devices (EPIDs) are commonly installed on modern linear accelerators (LINACs) and are convenient for imaging and, potentially, dosimetry. However, owing to their construction with metal and scintillating layers of high atomic number, they exhibit nonwater‐equivalent response and oversensitivity to low‐energy photons. Therefore, EPIDs are not ideal for dosimetry purposes. Additionally, nonlinearities due to the combined use of scintillators and photodiodes have been reported. Here, an EPID which employs a variable gain Gas Electron Multiplier (GEM) and direct detection of electrons is introduced. To investigate its dosimetric performance, measurements characterizing the novel EPID are performed and compared with measurements from ionization chambers and conventional EPIDs.

中文翻译：

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基于气体电子倍增器的外部束放射治疗剂量学检测器的表征

电子门禁成像设备（EPID）通常安装在现代线性加速器（LINAC）上，对于成像以及剂量测定很方便。但是，由于它们是由具有高原子序数的金属和闪烁层构成的，因此它们表现出非水等效的响应，并且对低能光子具有超敏性。因此，EPID对于剂量学目的不是理想的。另外，已经报道了由于闪烁体和光电二极管的组合使用而引起的非线性。在此，介绍了采用可变增益气体电子倍增器（GEM）和直接检测电子的EPID。为了研究其剂量测定性能，进行了表征新型EPID的测量，并将其与电离室和常规EPID的测量进行了比较。