Junwang Guo, Qingquan Yuan, Jianbo Cong, Lei Ma, Guofu Dong, Guoshan Yang, Ke Wu
Beijing Institute of Radiation Medicine, Beijing, China.
PLoS One. 2014 Sep 15;9(9):e106587. doi: 10.1371/journal.pone.0106587. eCollection 2014.
EPR tooth in vivo dosimetry is an attractive approach for initial triage after unexpected nuclear events. An X-band cylindrical TM010 mode resonant cavity was developed for in vivo tooth dosimetry and used in EPR applications for the first time. The cavity had a trapezoidal measuring aperture at the exact position of the cavity's cylindrical wall where strong microwave magnetic field H1 concentrated and weak microwave electric field E1 distributed. Theoretical calculations and simulations were used to design and optimize the cavity parameters. The cavity features were evaluated by measuring DPPH sample, intact incisor samples embed in a gum model and the rhesus monkey teeth. The results showed that the cavity worked at designed frequency and had the ability to make EPR spectroscopy in relative high sensitivity. Sufficient modulation amplitude and microwave power could be applied into the aperture. Radiation induced EPR signal could be observed remarkably from 1 Gy irradiated intact incisor within only 30 seconds, which was among the best in scan time and detection limit. The in vivo spectroscopy was also realized by acquiring the radiation induced EPR signal from teeth of rhesus monkey whose teeth was irradiated by dose of 2 Gy. The results suggested that the cavity was sensitive to meet the demand to assess doses of significant level in short time. This cavity provided a very potential option for the development of X-band in vivo dosimetry.
电子顺磁共振（EPR）牙齿体内剂量测定法是意外核事件后进行初步分诊的一种有吸引力的方法。开发了一种X波段圆柱形TM010模式谐振腔用于牙齿体内剂量测定，并首次用于电子顺磁共振应用。该谐振腔在其圆柱形壁的精确位置处有一个梯形测量孔，强微波磁场H1集中于此，弱微波电场E1分布于此。利用理论计算和模拟来设计和优化谐振腔参数。通过测量二苯基苦味酰基自由基（DPPH）样品、嵌入牙龈模型中的完整门牙样品和恒河猴牙齿来评估谐振腔的特性。结果表明，该谐振腔在设计频率下工作，具有以相对高灵敏度进行电子顺磁共振光谱分析的能力。可以向测量孔施加足够的调制幅度和微波功率。仅在30秒内就能从1 Gy照射的完整门牙中显著观察到辐射诱导的电子顺磁共振信号，这在扫描时间和检测限方面处于最佳水平之一。通过获取来自接受2 Gy剂量照射的恒河猴牙齿的辐射诱导电子顺磁共振信号，也实现了体内光谱分析。结果表明，该谐振腔灵敏度高，能够满足在短时间内评估显著剂量水平的需求。该谐振腔为X波段体内剂量测定的发展提供了一个非常有潜力的选择。
