在用于FLASH放射治疗的质子束中使用带硅传感器和裸芯片的Timepix3进行辐射测量
Radiation Measurements Using Timepix3 with Silicon Sensor and Bare Chip in Proton Beams for FLASH Radiotherapy
AI总结：
本研究利用Timepix3探测器（含GaAs、Si传感器及裸芯片）测量FLASH质子治疗中220 MeV质子束，通过提高Ikrum至80优化ToT响应，在布拉格坪区实现最高28 Gy/s剂量率下的束斑成像。
摘要：
本研究考察了Timepix3半导体像素探测器在不同强度质子束中的响应，重点关注FLASH质子治疗。利用Timepix3 ASIC芯片，我们测量了以短脉冲形式递送的220 MeV质子束的空间和能谱特性。实验装置包括以灵活架构与Timepix3芯片板集成的Minipix读出电子学，以及带硅传感器的Advapix Timepix3。测量使用配备GaAs和硅Si传感器的Timepix3探测器进行。我们还研究了裸Timepix3 ASIC芯片（无传感器）的响应。探测器被放置在连接到IBA Blue水模体的防水支架内，并在2 cm厚固体模体后的空气中进行了额外测量。结果表明，Timepix3探测器能够在常规和超高剂量率质子束中测量过阈时间（ToT）和计数率（事件数）。裸ASIC芯片配置可承受高达270 Gy/s的剂量率（DR），但由于探测效率低，其空间分辨率有限。相比之下，配备实验性GaAs传感器的Minipix Timepix3在低DR=5 Gy/s时即出现饱和。此外，Advapix Timepix3探测器在标准和定制配置下均被使用。在标准配置（Ikrum=5）下，探测器在DR=5 Gy/s时出现饱和。但在定制配置中，当每像素放电信号（Ikrum）增加到80时，探测器通过缩短ToT信号持续时间展现出增强的性能，从而能够在布拉格曲线的坪区实现高达DR=28 Gy/s的束斑成像。对于这样的DR，帧采集时间缩短至微秒量级，这意味着仅捕获了脉冲（脉冲长度为毫秒量级）的一小部分。
英文摘要：
This study investigates the response of Timepix3 semiconductor pixel detectors in proton beams of varying intensities, with a focus on FLASH proton therapy. Using the Timepix3 ASIC chip, we measured the spatial and spectral characteristics of 220 MeV proton beams delivered in short pulses. The experimental setup involved Minipix readout electronics integrated with a Timepix3 chipboard in a flexible architecture, and an Advapix Timepix3 with a silicon sensor. Measurements were carried out with Timepix3 detectors equipped with GaAs and silicon Si sensors. We also investigated the response of a bare Timepix3 ASIC chip (without a sensor). The detectors were placed within a waterproof holder attached to the IBA Blue water phantom, with additional measurements performed in air behind a 2 cm-thick solid phantom. The results demonstrated the capability of the Timepix3 detectors to measure time-over-threshold (ToT) and count rate (number of events) in both conventional and ultra-high-dose-rates proton beams. The bare ASIC chip configuration sustained up to a dose rate (DR) of 270 Gy/s, although it exhibited limited spatial resolution due to low detection efficiency. In contrast, Minipix Timepix3 with experimental GaAs sensors showed saturation at low DR=5 Gy/s. Furthermore, the Advapix Timepix3 detector was used in standard and customized configurations. In the standard configuration (Ikrum =5), the detector showed saturation at DR=5 Gy/s. But, in the customized configuration when the per-pixel discharging signal (Ikrum) was increased to 80, the detector demonstrated enhanced performance by reducing the duration of the ToT signal, allowing beam spot imaging up to DR=28 Gy/s in the plateau region of the Bragg curve. For such DR, the frame acquisition time was reduced to the order of microseconds, meaning only a fraction of the pulse (with pulse lengths on the order of milliseconds) was captured.
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