Radiation dose reconstruction from L-band in vivo EPR spectroscopy of intact teeth:: Comparison of methods
Radiation dose reconstruction from L-band in vivo EPR spectroscopy of intact teeth:: Comparison of methods
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DOI：
10.1016/j.radmeas.2007.05.025
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发表时间：
2007-07-01
影响因子：
2
通讯作者：
Swartz, H. M.
中科院分区：
文献类型：
--
作者：
Demidenko, E.;Williams, B. B.;Swartz, H. M.
体内EPR牙齿剂量测定是一个比体外EPR剂量测定更具挑战性的问题，因为与在活体受试者口腔中进行的测量相关的几个潜在的额外变异源。对于体内测量，使用较低的RF频率，并且与体外研究不同，不能处理牙齿以优化测量的釉质的量和构型。与体内测量有关的其他因素包括将谐振器定位在口腔中牙齿表面上的再现性、不规则的牙齿几何形状以及环境噪声的可能影响。因此，除了使用为分析来自体外牙齿测量的数据而开发的理论和经验模型之外，可能还需要其他非常规和更稳健的剂量重建方法。感兴趣的实验参数是光谱的峰到峰幅度，其通过校准曲线与辐射剂量相关以导出重建剂量。在这项研究中，我们描述和比较的结果，从七种类型的计算来测量的峰到峰的幅度估计的辐射诱导的信号。使用的数据来自三组辐照牙齿的体内测量。将六颗不同剂量的牙齿原位放置在志愿者的口中，并在三个不同的日子对每颗牙齿进行测量。预测的标准误差（SEP）被用作量化重建精度的品质因数。我们发现，许多方法给出了相当相似的结果，最好的预测误差来自于基于洛伦兹线模型的计算，该模型的中心场对应于牙齿的辐射诱导EPR谱的已知参数，并从作为数据采集方案的一部分测量的标准样品进行校正。当汇总三天测量的结果时，SEP显著降低，这表明数据变化的主要来源之一是精确标准化口腔内测量条件的能力。有非常合理的方法来实现现有程序的改进。(c)2007爱思唯尔有限公司保留所有权利。
In vivo EPR tooth dosimetry is a more challenging problem than in vitro EPR dosimetry because of several potential additional sources of variation associated with measurements that are made in the mouth of a living subject. For in vivo measurement a lower RF frequency is used and, unlike in the in vitro studies, the tooth cannot be processed to optimize the amount and configuration of the enamel that is measured. Additional factors involved with in vivo measurements include the reproducibility of positioning the resonator on the surface of the tooth in the mouth, irregular tooth geometry, and the possible influence of environmental noise. Consequently, in addition to using the theoretical and empirical models developed for analyzing data from measurements of teeth in vitro, other unconventional and more robust methods of dose reconstruction may be needed. The experimental parameter of interest is the peak-to-peak amplitude of the spectrum, which is correlated to the radiation dose through a calibration curve to derive the reconstructed dose. In this study we describe and compare the results from seven types of computations to measure the peak-to-peak amplitude for estimation of the radiation-induced signal. The data utilized were from three sets of in vivo measurements of irradiated teeth. Six different teeth with different doses were placed in the mouth of a volunteer in situ and measurements of each tooth were carried out on three different days. The standard error of prediction (SEP) is used as a figure of merit for quantifying precision of the reconstruction. We found that many of the methods gave fairly similar results, with the best error of prediction resulting from a computation based on a Lorentzian line model whose center field corresponds to the known parameter of the radiation-induced EPR spectra of teeth, with corrections from a standard sample that was measured as part of the data acquisition scheme. When the results from the three days of measurement were pooled, the SEP decreased dramatically, which suggests that one of the principal sources of variation in the data is the ability to precisely standardize the measurement conditions within the mouth. There are very plausible ways to accomplish improvements in the existing procedures. (c) 2007 Elsevier Ltd. All rights reserved.