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首页> 外文会议>Ocular radiation risk assessment in populations exposed to environmental radiation contamination >PHYSICAL AND RADIOBIOLOGICAL CONSIDERATIONS IN EYE DOSIMETRY
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PHYSICAL AND RADIOBIOLOGICAL CONSIDERATIONS IN EYE DOSIMETRY

机译：眼部剂量学中的物理和放射生物学考虑

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摘要

The most important parameters in radiological protection related to irradiation of superficial tissues are the nature and depth of the els at risk Hand the depth dose distribution to which they are subjected. This general problem is discussed in the context of exposure of the skin, testes and eye. In the case of the eye a survey of the radiobiological literature concerning animals and humans shows that the epithelial cells of the equatorial region of the lens are those which are involved in cataract induction. The depth of equatorial cells of the lens has been evaluated in the human eye by means of geometrical construction. The relevant dimensions have been determined from a survey of anatomical data supplemented by slit image photography and ultrasonic measurements. In a normal adult working population the minimum depth of equatorial epithelial cells in the lens range from 1.8 to 2.9 mm. The upper and lower values are associated with young and old subjects respectively. Calculations for Sr/Y-90 and Ru/Rh-106 isotropic beta sources give an indication of the range of doses to the target cells which are incurred in a working population - taking account of age dependence and variations in individual eye morphology. Calculations indicate that a planar dosemeter which integrates the tissue dose between depths of 2.5-3.5 mm should give a reasonable measure of the mean equatorial dose. The peak dose may be up to 50% higher. In situations where exposure arises from mixed fission products the dose to the lens is likely to be several times less than the surface/skin dose and several times more than the dose at a depth of 1 cm which is relevant to the evaluation of whole body exposure. The relationship between skin, eye and whole body dose will however be very dependent upon several factors including the particular mixture of radionuclides, the geometry of the source and environment, and the extent of fission product aging. To provide a prognosis in the case of an over exposure each of these factors need to be assessed on an individual basis. Because of the non-uniform exposure of the equatorial cells of the eye lens in beta radiation fields the cataract induction experience of cohorts such as the Japanese bomb survivors may not necessarily be directly applicable to nuclear industry workers exposed to fission and neutron activation products. In the case of acute high dose eye exposures, particularly from weakly penetrating radiations (including hot particle exposures) the possibility ofrncorneal ulceration is likely to be of greatest concern. In the absence of more definitive information it would appear to be defensible to treat this situation, in terms of dose evaluation, in the same way as for skin exposure.
机译：在放射防护中，与浅表组织的照射有关的最重要参数是处于危险中的els的性质和深度。在皮肤，睾丸和眼睛暴露的情况下讨论了这个一般性问题。就眼睛而言，有关动物和人类的放射生物学文献的调查显示，晶状体赤道区域的上皮细胞是参与白内障诱导的细胞。已经通过几何构造在人眼中评估了晶状体的赤道细胞的深度。已经通过对解剖数据的调查确定了相关尺寸，并补充了狭缝图像摄影和超声波测量。在正常的成年人工作人群中，晶状体中赤道上皮细胞的最小深度为1.8至2.9 mm。较高和较低的值分别与年轻和老年受试者相关。 Sr / Y-90和Ru / Rh-106各向同性β离子源的计算结果表明了工作人群中目标细胞的剂量范围-考虑到年龄依赖性和个体眼睛形态的变化。计算表明，在2.5-3.5 mm的深度之间对组织剂量进行积分的平面剂量计应能合理测量平均赤道剂量。峰值剂量可能会高出50％。在混合裂变产物引起暴露的情况下，镜片的剂量可能比表面/皮肤的剂量少几倍，而在1 cm深度处的剂量则多几倍，这与评估全身暴露有关。但是，皮肤，眼睛和全身剂量之间的关系将非常取决于几个因素，包括放射性核素的特定混合物，放射源和环境的几何形状以及裂变产物老化的程度。为了在过度暴露的情况下提供预后，需要单独评估这些因素中的每一个。由于在β射线辐射场中晶状体的赤道细胞暴露不均匀，因此诸如日本炸弹幸存者之类的人群的白内障诱导经验可能不一定直接适用于暴露于裂变和中子活化产物的核工业工人。在急性高剂量眼部暴露的情况下，尤其是弱穿透辐射（包括热粒子暴露）引起的角膜溃疡的可能性可能是最令人关注的问题。在缺乏更确切的信息的情况下，就剂量评估而言，以与皮肤暴露相同的方式治疗这种情况似乎是合理的。

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