Abstract The characterization of high intensity charged particle beams at medical accelerators poses several challenges. In this work, we investigate the use of a highly segmented CMOS Image Sensors (CIS), an MT9T031 from Aptina, as a way to study the spatial homogeneity and the time stability of the beam. The approach relies on the possibility to define many adjacent small regions that perform the radiation flux measurement with sufficient precision (below 1%) to extract the spatial structure of the beam. The device has been exposed to a 10 MeV therapeutic electron beam at Santa Maria Hospital (Terni, Italy) to measure the electron flux at a distance of 140 cm. The whole sensor, using a non-linear calibration, has measured the value of the flux, then the segmentation approach has been applied to study the spatial structure of the beam. Concerning the variation in time, the current limitation of a rolling shutter CIS limits the capability to disentangle the time structure of the beam. However, in light of the possibility to obtain some CIS with the new global shutter architecture, having integration time of the order of a few tens of microseconds, the measurement procedure has been implemented and tested using ∼ 1 H z frequency frame-rate, to study its limits. Uncertainty of the order of 0.5% has been reached for measurement of both spatial and time beam homogeneity.

中文翻译：

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使用高度像素化 CMOS 图像传感器的临床电子束的初步研究

摘要 医用加速器中高强度带电粒子束的表征提出了几个挑战。在这项工作中，我们研究了使用高度分段的 CMOS 图像传感器 (CIS)，来自 Aptina 的 MT9T031，作为研究光束空间均匀性和时间稳定性的一种方式。该方法依赖于定义许多相邻小区域的可能性，这些区域以足够的精度（低于 1%）执行辐射通量测量，以提取光束的空间结构。该设备已在圣玛丽亚医院（意大利特尔尼）暴露于 10 MeV 治疗电子束，以测量 140 cm 距离处的电子通量。整个传感器使用非线性校准，测量通量值，然后应用分割方法研究光束的空间结构。关于时间变化，卷帘快门 CIS 的电流限制限制了解开光束时间结构的能力。然而，考虑到使用新的全局快门架构获得一些 CIS 的可能性，集成时间约为几十微秒，测量程序已使用 ~ 1 Hz 频率帧速率实施和测试，以研究它的极限。空间和时间光束均匀性的测量达到了 0.5% 的不确定度。已使用 ~ 1 Hz 频率帧速率实施和测试了测量程序，以研究其限制。空间和时间光束均匀性的测量达到了 0.5% 的不确定度。已使用 ~ 1 Hz 频率帧速率实施和测试了测量程序，以研究其限制。空间和时间光束均匀性的测量达到了 0.5% 的不确定度。