Iodine-containing contrast media (ICM) are extensively used to improve image quality and information content in x-ray-based examinations, particularly in computed tomography (CT). In parallel, there is increasing evidence that the use of ICM during CT sessions is associated with deoxyribonucleic acid (DNA) breaks that may influence the estimation of the risks linked to x-ray exposure. Why has iodine been preferred to any other heavy elements to enhance contrast in radiodiagnostics? How to understand such DNA breaks effect? We searched for the answers in the early times of x-ray medical use. It appeared that the maximal ratio between the relative iodine and water mass energy absorption coefficients is reached in the range of 40–60 keV, which defines the energy range in which the dose is preferentially absorbed by ICM. This range does not correspond to the K-edge of iodine but to that of tungsten, the major component of the x-ray tube anode of CT scanners. At such energy, radiolysis of the ICM produces sodium or potassium iodide that prevents a normal DNA breaks repair and influences the individual response to x-ray low-dose. Both contrast enhancement and DNA breaks effect may therefore be caused by tungsten of the anodes of x-ray tubes.

中文翻译：

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放射诊断中含碘造影剂引起的DNA断裂：钨的问题？

含碘的造影剂（ICM）被广泛用于改善基于x射线的检查中的图像质量和信息含量，尤其是在计算机断层扫描（CT）中。同时，越来越多的证据表明，在CT会话中使用ICM与脱氧核糖核酸（DNA）断裂有关，这可能会影响与X射线照射有关的风险的估计。为什么在放射诊断中碘比其他重元素更受青睐？如何理解这种DNA断裂的作用？我们在X射线医疗使用的早期就寻找了答案。看来，相对碘和水质能量吸收系数之间的最大比值达到40-60 keV，这定义了ICM优先吸收剂量的能量范围。该范围不对应于碘的K边缘，而是对应于钨的K边缘，钨是CT扫描仪X射线管阳极的主要成分。在这种能量下，ICM的放射分解会产生碘化钠或碘化钾，从而阻止正常的DNA破坏修复并影响个体对X射线低剂量的反应。因此，X射线管阳极的钨可能会引起对比度增强和DNA断裂效应。