Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig, Germany.
Phys Med Biol. 2011 Jan 21;56(2):415-37. doi: 10.1088/0031-9155/56/2/009. Epub 2010 Dec 22.
In recent years, several papers dealing with the eye lens dose have been published, because epidemiological studies implied that the induction of cataracts occurs even at eye lens doses of less than 500 mGy. Different questions were addressed: Which personal dose equivalent quantity is appropriate for monitoring the dose to the eye lens? Is a new definition of the dose quantity H(p)(3) based on a cylinder phantom to represent the human head necessary? Are current conversion coefficients from fluence to equivalent dose to the lens sufficiently accurate? To investigate the latter question, a realistic model of the eye including the inner structure of the lens was developed. Using this eye model, conversion coefficients for electrons have already been presented. In this paper, the same eye model-with the addition of the whole body-was used to calculate conversion coefficients from fluence (and air kerma) to equivalent dose to the lens for photon radiation from 5 keV to 10 MeV. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are similar between 40 keV and 1 MeV and lower by up to a factor of 5 and 7 for photon energies at about 10 keV and 10 MeV, respectively. Above 1 MeV, the new values (calculated without kerma approximation) should be applied in pure photon radiation fields, while the values adopted by the ICRP in 1996 (calculated with kerma approximation) should be applied in case a significant contribution from secondary electrons originating outside the body is present.
近年来，已经发表了几篇关于晶状体剂量的论文，因为流行病学研究表明，即使晶状体剂量低于 500mGy，也会诱发白内障。不同的问题被提出来：哪种个人剂量当量适用于监测晶状体剂量？是否需要基于圆柱体模型来定义新的剂量量 H(p)(3)，以代表人类头部？目前从注量到晶状体当量剂量的转换系数是否足够准确？为了研究后者的问题，开发了一个包括晶状体内部结构的真实眼睛模型。使用这个眼睛模型，已经提出了电子的转换系数。在本文中，使用相同的眼睛模型——增加整个身体——计算了从光子辐射从 5keV 到 10MeV 的注量（和空气比释动能）到晶状体当量剂量的转换系数。与 1996 年国际辐射防护委员会（ICRP）采用的值相比，新值在 40keV 到 1MeV 之间相似，在约 10keV 和 10MeV 的光子能量下，新值分别低了 5 倍和 7 倍。在 1MeV 以上，应在纯光子辐射场中应用新值（无比释动能近似计算），而在存在源自身体外部的次级电子的显著贡献的情况下，应应用 1996 年 ICRP 采用的值（比释动能近似计算）。
