The precise characterization of neutron beams is a cornerstone of Boron Neutron Capture Therapy (BNCT). While Instrumental Neutron Activation Analysis (INAA) is the standard technique for neutron flux measurement, it is limited in its ability to capture two-dimensional (2D) reaction rate distributions. This study aims to validate the Indirect Neutron Radiography (INR) method for 2D reaction rate quantification, addressing critical variables such as temperature sensitivity and signal fading. We designed and constructed an optimized INR platform comprising an Imaging Plate (IP), readout device, activation detectors (copper foils), and real-time temperature monitoring. Comprehensive experiments were conducted to investigate the impact of ambient temperature and fading time on IP signal reliability. A robust calibration curve was formulated, linking IP signals to dose deposition metrics, thereby enabling precise reaction rate assessments. The study found that IP signals are minimally sensitive to temperature variations (less than 0.1% change per 1 °C), but are subjected to linear fading over time, necessitating stringent temperature control and time-dependent signal corrections. A mathematical relationship between IP signals and dose deposition was established, represented by . Application of the INR method revealed that the depth-dependent reaction rates in copper strips closely aligned with those acquired through INAA, exhibiting a relative deviation of less than 5% within a 4cm depth range inside the phantom. Our findings demonstrate that the INR method offers a robust alternative to traditional INAA for capturing 2D reaction rates, effectively addressing complexities like temperature sensitivity and signal fading. While challenges persist, particularly in the realm of measurement errors, this study lays the groundwork for further methodological refinements and broadens the scope for future research in BNCT neutron beam characterization.

中文翻译：

---

推进 BNCT 中的二维反应速率测量：间接中子射线照相方法的验证

中子束的精确表征是硼中子捕获疗法 (BNCT) 的基石。虽然仪器中子活化分析 (INAA) 是中子通量测量的标准技术，但它捕获二维 (2D) 反应速率分布的能力有限。本研究旨在验证用于二维反应速率量化的间接中子射线照相 (INR) 方法，解决温度敏感性和信号衰落等关键变量。我们设计并构建了一个优化的 INR 平台，包括成像板 (IP)、读出设备、激活探测器（铜箔）和实时温度监测。我们进行了综合实验来研究环境温度和衰落时间对 IP 信号可靠性的影响。制定了稳健的校准曲线，将 IP 信号与剂量沉积指标联系起来，从而实现精确的反应速率评估。研究发现，IP 信号对温度变化的敏感度最低（每 1 °C 的变化小于 0.1%），但会随着时间的推移而发生线性衰落，因此需要严格的温度控制和与时间相关的信号校正。建立了 IP 信号和剂量沉积之间的数学关系，用 表示。 INR 方法的应用表明，铜条中的深度依赖性反应速率与通过 INAA 获得的反应速率密切相关，在模型内部 4 厘米深度范围内表现出小于 5% 的相对偏差。我们的研究结果表明，INR 方法为捕获 2D 反应速率提供了传统 INAA 的可靠替代方案，有效解决了温度敏感性和信号衰落等复杂问题。尽管挑战依然存在，特别是在测量误差领域，但这项研究为进一步完善方法论奠定了基础，并拓宽了 BNCT 中子束表征未来研究的范围。