Martin C J, Sutton D G, Magee J, McVey S, Williams J R, Peet D
Health Physics, Gartnavel Royal Hospital, 1055 Great Western Road, Glasgow G12 0XH, UK.
J Radiol Prot. 2012 Dec;32(4):373-96. doi: 10.1088/0952-4746/32/4/373. Epub 2012 Sep 24.
Computed tomography (CT) scanning rooms and interventional x-ray facilities with heavy workloads may require the installation of shielding to protect against radiation scattered from walls or ceiling slabs. This is particularly important for the protection of those operating x-ray equipment from within control cubicles who may be exposed to radiation scattered from the ceiling over the top of the protective barrier and round the side if a cubicle door is not included. Data available on the magnitude of this tertiary scatter from concrete slabs are limited. Moreover, there is no way in which tertiary scatter levels can be estimated easily for specific facilities. There is a need for a suitable method for quantification of tertiary scatter because of the increases in workloads of complex x-ray facilities. In this study diagnostic x-ray air kerma levels scattered from concrete and brick walls have been measured to verify scatter factors. The results have been used in a simulation of tertiary scatter for x-ray facilities involving summation of scatter contributions from elements across concrete ceiling slabs. The majority of the ceiling scatter air kerma to which staff behind a barrier will be exposed arises from the area between the patient/x-ray tube and the staff. The level depends primarily on the heights of the ceiling and protective barrier. A method has been developed to allow tertiary scatter levels to be calculated using a simple equation based on a standard arrangement for rooms with different ceiling and barrier heights. Coefficients have been derived for a CT facility and an interventional suite to predict tertiary scatter levels from the workload, so that consideration can be given to the protection options available.
对于工作量较大的计算机断层扫描（CT）室和介入X射线设备，可能需要安装屏蔽设施，以防护从墙壁或天花板散射的辐射。这对于保护在控制小室内操作X射线设备的人员尤为重要，因为如果小室没有门，他们可能会受到从防护屏障上方天花板散射以及从侧面散射过来的辐射。关于混凝土板产生的这种二次散射强度的数据有限。此外，对于特定设施，无法轻松估算二次散射水平。由于复杂X射线设备工作量的增加，需要一种合适的方法来量化二次散射。在本研究中，已测量了从混凝土墙和砖墙散射的诊断X射线空气比释动能水平，以验证散射因子。这些结果已用于模拟X射线设备的二次散射，其中包括对混凝土天花板各部分散射贡献的求和。屏障后工作人员所受的大部分天花板散射空气比释动能来自患者/X射线管与工作人员之间的区域。该水平主要取决于天花板和防护屏障的高度。已开发出一种方法，可根据不同天花板和屏障高度房间的标准布置，使用一个简单方程来计算二次散射水平。已推导出CT设备和介入手术室的系数，以根据工作量预测二次散射水平，从而能够考虑可用的防护方案。
