Martin Colin J
Department of Clinical Physics and Bio-engineering, University of Glasgow, Glasgow, Scotland, UK
Radiat Prot Dosimetry. 2015 Jul;165(1-4):376-81. doi: 10.1093/rpd/ncv040. Epub 2015 Mar 25.
Scattered radiation makes up the majority of the stray radiation field around an X-ray unit. The scatter is linked to the amount of radiation incident on the patient. It can be estimated from quantities used to assess patient dose such as the kerma-area product, and factors have been established linking this to levels of scattered radiation for radiography and fluoroscopy. In radiography shielding against primary radiation is also needed, but in other modalities this is negligible, as the beam is intercepted by the image receptor. In the same way scatter from CT can be quantified in terms of dose-length product, but because of higher radiation levels, exposure to tertiary scatter from ceilings needs to be considered. Transmission requirements are determined from comparisons between calculated radiation levels and agreed dose criteria, taking into account the occupancy of adjacent areas. Thicknesses of shielding material required can then be calculated from simple equations.
散射线构成了X射线设备周围杂散辐射场的大部分。散射与入射到患者身上的辐射量有关。它可以根据用于评估患者剂量的量（如比释动能面积乘积）来估算，并且已经确定了将其与X射线摄影和透视的散射线水平相关联的因素。在X射线摄影中，还需要对原发射线进行屏蔽，但在其他成像方式中，由于射线被图像接收器拦截，原发射线的屏蔽可忽略不计。同样，CT的散射可以根据剂量长度乘积进行量化，但由于辐射水平较高，需要考虑来自天花板的三次散射的照射。传输要求是通过比较计算出的辐射水平和商定的剂量标准来确定的，同时要考虑相邻区域的人员占用情况。然后可以根据简单的公式计算所需屏蔽材料的厚度。
