Program in Biomedical Radiation Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 08826, Republic of Korea.
Ionizing Radiation Metrology Group, Korea Research Institute of Standards and Science, Daejeon 34113, Republic of Korea.
J Magn Reson. 2023 Aug;353:107520. doi: 10.1016/j.jmr.2023.107520. Epub 2023 Jul 9.
This article describes the design process for a motion compensation system that can suppress the spectral distortion caused by human motion and breathing during in-vivo electron paramagnetic resonance (EPR) spectroscopy on an intact incisor. The developed system consists of two elements: an electronically controlled tunable resonator and an automatic control circuit (ACC). The resonator can modify the resonant frequency and impedance by tuning and matching the voltage, while the ACC can generate a feedback signal using phase-sensitive detection (PSD). The signal is transferred into the resonator to maintain the critical coupling state. The tunable frequency range of the resonator was measured at over 10 MHz, offering approximately eight times the required range. The bandwidth of the resonator fluctuated in a negligible range (0.14% relative standard error) following the resonant frequency. With the feedback signal on, in-vivo EPR measurements were demonstrated to be a stable baseline with 35% higher signal-to-noise ratio (SNR). When one incisor sample was irradiated by an X-ray instrument, the EPR signal responses to the absorbed doses of 0-10 Gy exhibited high linearity (R = 0.994). In addition, the standard error of inverse prediction was estimated to be 0.35 Gy. The developed system achieved a discrimination ability of 2 Gy, which is required for triage in large-scale radiation accidents. Moreover, the compensation is fully automated, meaning that the system can be operated with simple training in an emergency.
本文描述了一种运动补偿系统的设计过程，该系统可抑制活体电子顺磁共振（EPR）光谱学中由于人体运动和呼吸引起的光谱失真。所开发的系统由两个部分组成：电子控制可调谐谐振器和自动控制电路（ACC）。通过调节和匹配电压，谐振器可以修改谐振频率和阻抗，而 ACC 可以使用相敏检测（PSD）生成反馈信号。该信号被传输到谐振器中以维持临界耦合状态。测量到的谐振器可调谐频率范围超过 10 MHz，提供了大约所需范围的八倍。谐振器的带宽在跟随谐振频率时在可忽略的范围内波动（相对标准误差为 0.14%）。在反馈信号开启的情况下，活体 EPR 测量显示出稳定的基线，信号噪声比（SNR）提高了 35%。当一个门牙样本被 X 射线仪器照射时，EPR 信号对 0-10 Gy 的吸收剂量表现出高度的线性（R = 0.994）。此外，反预测的标准误差估计为 0.35 Gy。所开发的系统实现了 2 Gy 的辨别能力，这是在大规模辐射事故中进行分类所必需的。此外，补偿是完全自动化的，这意味着在紧急情况下，系统可以通过简单的培训进行操作。
