辐射事故剂量范围照射后塑料假牙材料的顺磁共振特性

ESR CHARACTERISTICS OF IRRADIATED ARTIFICIAL TOOTH MATERIALS IN ACCIDENT DOSE RANGE

用电子顺磁共振（ＥＳＲ）技术对两种常用假牙材料（聚甲基丙烯酸甲酯和拜耳树脂）的剂量学特性研究结果如下：在０～２０Ｇｙ６０Ｃｏγ射线照后，两种材料中均被诱发出新的信号，其ｇ值范围为１．９９４２～２．０１４４。聚甲基丙烯酸甲酯在上述剂量范围内信号强度对照射剂量呈线性响应（ｒ＝０．９７），且信号线宽也随剂量有明显变化。而拜耳树脂在８Ｇｙ以下响应呈正相关，而后响应出现饱和。如照后即刻测量，两种材料可测量下限均不大于２Ｇｙ。在人体体温３７℃下，信号２４ｈ后平均衰减４０％，而后的一周内衰减较慢，约１０％。如照后低温（－２５℃）保存，衰减速度可大大减低，一周内总衰减约２５％－３０％。上述结果表明，如能在事故后及早测量或低温保存样品，两种常用假牙材料都具有充当辐射事故剂量ＥＳＲ检测材料的可能性。其中拜耳假牙难以用于８Ｇｙ以上剂量范围。

Two kinds of artificial tooth materials (polymethylmethylacrylate abbreviated as PMMA and Bayer polymer) were investigated by detecting the characteristics of 60Co γ-ray induced ESR signals. The results are as follows:Both of the two materials have a dose related signal which located at a g-factor range of 1 .9942～2.0144. The signal intensity of PMMA had a linear response to irradiation dose (r = 0.97) in range of 0-20 Gy. The linewidth also varied along with the dose increment. Bayer polymer had a positive relative dose response below & Gy. The response would get saturation at doses higher than8 Gy. The lowest detectable dose threshold for both of the two materials were about 2 Gy. The fading speed of the signal might be about 40% for the first 24 hours after irradiation if stored at imitated human body temperature (37C) and it would get relatively stable when the samples were stored at lower temperature (-25℃).In this case,the fading speed might decreased to about 25%～30% during the first week.The above results suggests that artificial tooth materials of PMMA and Bayer polymer can be used as applicative ESR dosimetry materials for nuclear accidental dose evaluation.