Miyake M, Liu K J, Walczak T M, Swartz H M
EPR Center for the Study of Viable Biological Systems, Dartmouth Medical School, Hanover, NH 03755, USA.
Appl Radiat Isot. 2000 May;52(5):1031-8. doi: 10.1016/s0969-8043(00)00053-1.
Low frequency electron paramagnetic resonance (EPR) provides the potential advantage of making accurate and sensitive measurements of absorbed radiation dose in teeth in situ, i.e. without removing the teeth from the potential victim. The potential limiting factors for making such measurements are: (1) whether low frequency EPR is sufficiently sensitive to detect radiation-induced signal in human teeth; (2) whether sufficient sensitivity can be maintained under in vivo conditions. In this manuscript, we summarize results indicating that this approach is feasible. Using 1.2 GHz EPR spectroscopy, we found that the lower limit for these measurements in isolated human teeth is 0.2 Gy or lower. Measurements of radiation-induced EPR signals in the teeth of living rats were achieved with sufficient sensitivity to indicate that, when taking into consideration the larger mass of human teeth, similar measurements in human teeth in situ would provide sensitivity in the dose range for potential accidental exposures. We estimate that the current lower limit for detecting radiation doses in human teeth in situ (in vivo) is 0.5-1.0 Gy; this would be sufficient for determining if a person has been exposed to potentially life threatening doses of ionizing radiation. The limiting factor for sensitivity appears to be background signals rather than signal/noise, and there are feasible means to overcome this problem and further increase sensitivity. The additional instrumental developments required to make an effective in vivo EPR dosimetric spectrometer for the measurements in teeth in human subjects in situ, seem quite achievable.
低频电子顺磁共振（EPR）具有在原位测量牙齿吸收辐射剂量的潜在优势，即在不将牙齿从潜在受害者身上取出的情况下进行测量。进行此类测量的潜在限制因素包括：（1）低频EPR是否足够灵敏以检测人牙中的辐射诱导信号；（2）在体内条件下能否保持足够的灵敏度。在本论文中，我们总结了表明该方法可行的结果。使用1.2 GHz的EPR光谱学，我们发现孤立人牙中这些测量的下限为0.2 Gy或更低。在活体大鼠牙齿中对辐射诱导的EPR信号进行测量时，灵敏度足以表明，考虑到人类牙齿的质量更大，原位在人牙中进行类似测量将在潜在意外照射的剂量范围内提供灵敏度。我们估计，目前原位（体内）检测人牙辐射剂量的下限为0.5 - 1.0 Gy；这足以确定一个人是否受到了可能危及生命的电离辐射剂量照射。灵敏度的限制因素似乎是背景信号而非信噪比，并且有可行的方法来克服这个问题并进一步提高灵敏度。制造一种有效的用于原位测量人体受试者牙齿的体内EPR剂量测定光谱仪所需的额外仪器开发似乎是完全可以实现的。
