测量近距离治疗源活度的井型电离室研制

Development of a well- type chamber for measurement of source activation in breachtherapy

目的研制井型电离室,测量近距离源空气比释动能强度,与国际标准测量物理量接轨,改善源活度的测量精确度,促进国内近距离剂量学的发展。方法吸取国外先进经验,结合本国国情,设计方案,绘制图纸,对井型电离室所有材料进行筛选,加工,组装,并开展性能实验。结果用国外进口的井型电离室和研制的井型电离室在相同条件下比对,结果:井型电离室长期稳定性为0.4%,技术指标为2%;电离电荷复合率为0.9995,技术指标0.9996;井型电离室重复性为0.02%,技术指标为0.5%。井型电离室的最佳驻留位置在平坦峰值区范围内灵敏度固定没有变化,进口井型电离室的最佳驻留位置在平坦峰值5mm范围内灵敏度变化为0.1%。结论该电离室优点:测量快速准确,同时可以测量192Ir,125I和103Pd等放射源活度。测量范围从3.7MBq～7.4×105MBq。该井型电离室将填补我国现场检测仪器的空白,并能形成我国有自主知识产权的产品。

Objective To develop a well-type chamber air kerma strength of source for measurement and improve accuracy for source activity. Methods By drawing advanced experience from abroad and combining the condition of our country, we designed a plan, drew the blueprint, selected the material, processed and assembled the well- type chamber, and carried out a performance test. Result The imported and self-made well- type chambers were measured in the same condition for comparision. The results should that the long- term stability of the self-made well- type chamber is 0.4%, and the technique index is 2% ; the recombination rate of ionized charges is 0.9995% and the technique index is 1.000; the measurement accuracy of the well-type chamber is 0.02% ,and the technique index is 0.5%. For the self-made well-type chamber, the flat response of peak sensitivity is fixed while for imported one the flat response changes around 0.1% within 5 mm of peak sensitivity. ConcIusions The strong points of the self-made well-type chamber are quick speed and accuracy in measurement and can measure for ^192Ir, ^125I and ^103Pd sources. Its measurement range is from 3.7 MBq to 7.4 ×10^5 MBq. The development of the well-type chamber fills the gaps of on -site becomes a product with independent intellectual property right in our country. t instruments and