牙齿自由基在体测量方法及其辐射剂量诊断应用

The early and rapid diagnostic of radiation dose for individuals by in vivo measurement of free radicals in tooth,which is a very interested research topic nowadays, has been becoming an effective method to solve the problems in medical countermeasure against nulear and radiation emergency and then has the important social significance as well as the value of practical application.In this work, problems urgent need to solve in this area will be explored and solved in two ways: Firstly,new kind of X-band ESR cavities of high sensitivity and with special inside reference label structure will be developed. The intensity of free radicals in tooth measured in vivo will be calibrated by the signal of inside reference label and then be normalized according to different measurement conditions.The problems of low sensitivity and signal unstability induced by process of in vivo measurement will get substantially overcome therefore the reliability of measurement results will be improved and the low detectable dose limit will be decreased to the level of lease than 1Gy. This will be very important for radiation emergency dosimetry. secondly, based on the method above, actual conditions of in vivo measurement will be simulated by experiments with animals or volunteers.The influence factors induced from in vivo measurement process will be inspected and the weight factor of each non-dose influence source will be analyzed to conclude practical comprehensive calibration model and calibration method. Hence,reasonable and reliable dose response feature applying to in vivo measurement conditions will finally be set up in order to ensure the accuracy of radiation dose assessment of people in vivo in practical application.

通过在体测量牙齿自由基实现辐射剂量早期快速诊断，是解决核与辐射突发事件医学应急所面临问题的有效途径，也是当前的研究热点，具有重要的社会意义和实用价值。本项目拟从两方面解决该领域目前的现实问题。首先，研制带有内标刻度装置的高灵敏度新型X波段电子自旋共振（ESR）谐振腔，利用稳定的内标信号对牙齿自由基信号强度进行状态归一化刻度，解决在体测量灵敏度低和信号状态不稳定问题，提高测量结果的可靠性并降低剂量测量下限至小于1Gy,该指标对于人体辐射剂量应急诊断至关重要；在此基础上，通过模拟在体测量实验条件，鉴别各种由在体测量引起的特殊干扰因素，归纳分析各种影响因素的权重系数，进而建立对各类非剂量因素影响测量结果的校正模型和校正方法，最终获得客观可靠的辐射剂量在体测量剂量响应规律，为人体剂量在体测量的实际应用奠定基础。

研制了具有自主知识产权的新型在体测量牙齿自由基专用X波段ESR谐振腔，该腔体综合考虑了在体测量牙齿条件下的技术要求，在确保高灵敏度前提下，使检测口更适于整体牙齿测量并含有内标刻度装置等特殊结构，可以测量单颗牙齿的剂量下限约1Gy。研制了稳定的Mn 2+型腔内标样品和仿牙釉质碳掺杂羟基磷灰石样品，分别用来对测量状态进行归一化刻度和模拟辐照后牙齿自由基信号的在体测量环境；系统研究了牙齿表面水对微波的介电损耗、牙齿体积和形状的个体差异及人体生理活动等非剂量因素对在体测量的影响，分析了各种影响因素对在体测量的影响程度，建立了相应的校正方法，编制了多功能综合软件系统，初步建立了客观的人牙齿剂量在体测量评估方法。利用本项目建立的实验平台和技术方法，还开展了人指甲自由基ESR在体测量实验，初步实现了指甲剂量在体测量，进一步验证了所研制设备和建立的在体测量方法的实用性。本课题研究结果为人体剂量在体测量的实际应用奠定了基础。