Electronic portal imaging devices (EPIDs) lend themselves to beams-eye view clinical applications, such as tumor tracking, but are limited by low contrast and detective quantum efficiency (DQE). We characterize a novel EPID prototype consisting of multiple layers and investigate its suitability for use under clinical conditions. A prototype multi-layer imager (MLI) was constructed utilizing four conventional EPID layers, each consisting of a copper plate, a Gd2O2S:Tb phosphor scintillator, and an amorphous silicon flat panel array detector. We measured the detector’s response to a 6 MV photon beam with regards to modulation transfer function, noise power spectrum, DQE, contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and the linearity of the detector’s response to dose. Additionally, we compared MLI performance to the single top layer of the MLI and the standard Varian AS-1200 detector. Pre-clinical imaging was done on an anthropomorphic phantom, and the detector’s CNR, SNR and spatial resolution were assessed in a clinical environment. Images obtained from spine and liver patient treatment deliveries were analyzed to verify CNR and SNR improvements. The MLI has a DQE(0) of 9.7%, about 5.7 times the reference AS-1200 detector. Improved noise performance largely drives the increase. CNR and SNR of clinical images improved three-fold compared to reference. A novel MLI was characterized and prepared for clinical translation. The MLI substantially improved DQE and CNR performance while maintaining the same resolution. Pre-clinical tests on an anthropomorphic phantom demonstrated improved performance as predicted theoretically. Preliminary patient data were analyzed, confirming improved CNR and SNR. Clinical applications are anticipated to include more accurate soft tissue tracking.

电子射野成像设备 (EPID) 适合光束眼视图临床应用，例如肿瘤跟踪，但受到低对比度和检测量子效率 (DQE) 的限制。我们描述了一种由多层组成的新型 EPID 原型，并研究了其在临床条件下使用的适用性。原型多层成像器 (MLI) 采用四个传统 EPID 层构建，每个层由铜板、Gd2O2S:Tb 荧光粉闪烁体和非晶硅平板阵列探测器组成。我们测量了探测器对 6 MV 光子束的响应，包括调制传递函数、噪声功率谱、DQE、对比度噪声比 (CNR)、信噪比 (SNR) 以及探测器线性度对剂量的反应。此外，我们还将 MLI 性能与 MLI 的单个顶层和标准 Varian AS-1200 探测器进行了比较。临床前成像是在拟人体模上完成的，并在临床环境中评估探测器的 CNR、SNR 和空间分辨率。对从脊柱和肝脏患者治疗过程中获得的图像进行分析，以验证 CNR 和 SNR 的改善。 MLI 的 DQE(0) 为 9.7%，约为参考 AS-1200 探测器的 5.7 倍。噪声性能的改善很大程度上推动了这一增长。与参考相比，临床图像的 CNR 和 SNR 提高了三倍。一种新的 MLI 被表征并准备用于临床转化。 MLI 显着提高了 DQE 和 CNR 性能，同时保持相同的分辨率。对拟人模型的临床前测试表明，正如理论上预测的那样，性能得到了改善。对初步患者数据进行了分析，证实了 CNR 和 SNR 的改善。 预计临床应用将包括更准确的软组织跟踪。