PuO_2颗粒对自发α射线的能量自吸收效应评估研究

Evaluation of Self-absorption Effect of α-rays Emitted Spontaneously in Plutonium Oxide

构建PuO_2颗粒状α发射体的球体几何模型,采用蒙特卡罗和射程经验公式模拟计算α射线在PuO_2颗粒中的射程能量关系式及α射线从PuO_2颗粒表面出射的能谱分布,研究因PuO_2颗粒对自发α射线的能量自吸收效应导致的对人体内照射剂量评估的影响。研究结果表明,PuO_2粒径越大,其对自发α射线的能量自吸收效应越明显,内照射剂量的修正效果越好;当PuO_2粒径在2μm以上时,内照射剂量的修正效果大于5%。本研究的结果对吸入放射性物质所致人体内照射剂量的准确估算有重要的参考价值,并可应用于放射性核素肿瘤治疗等领域的微剂量学研究。

A sphere geometry model for plutonium oxide-based alpha emitter was setup. The range of alpha particle in plutonium oxide pellet versus its energy and the spectral distribution of alpha particle emerging from the emitter surface were calculated using Monte Carlo method combined with the empirical formula of range. The internal radiation dose resulted by self-absorption effect of α-rays emitted spontaneously in plutonium oxide was investigated accordingly. The result shows that the larger particle size the plutonium oxide-based alpha emitter has, the more obvious the self-absorption effect is and the better the correction effect of the intake absorbed dose that effects on human lung has. For plutonium oxide pellet with its particle size exceeding 2 μm, the correction quantity is expected to be larger than 5%. Our work is beneficial for a precise evaluation of internal radiation dose induced by inhaled radioactive material and microdosimetry study in radionuclide tumor therapy.