数字X射线图象的形成是一个X射线信息影象的形成、转换和传递的复杂过程，且通常得到的数字X射线图象的灰度值没有准确的物理意义.在实验的基础上，提出了一种基于朗伯定律的理想图象模型，用以对数字X射线图象进行灰度的校正及线性化.经过这样的处理后，图象的灰度值与吸收体厚度之间的关系近似为线性，这对于人体特征参数的定量分析（如对心脏形态、血流的分析，以及在DSA中对造影剂浓度的分析等）具有重要作用.%The generation of a digital X-ray image is such a complex process which includes the production, the conversion and the transform of the X-ray information. Generally, the interactions between X-ray and other material include photoelectric absorption and comptom scattering, which have relations to the material's mass, density, equivalently atomic weight and the energy of X-ray. In clinical use, X-ray has a wide spectrum similar to the daylight, so its intensity will become harder and harder with different rate during it penetrates other material. Such nonlinearity and other stochastic noise will make a digital X-ray image has no exact physical means. Due to the physical comparability, we use aluminium and lucite to simulate bone and software respectively, and image them under each kind of material thickness, then we can obtain an ideal image model use part of these data, which can be used to calibrate and linearize the X-ray image. This method will be advantageous to the quantitative analysis of the human's physiological parameters such as the cardiac configuration, the blood flow, and the density of the contrast media in DSA.
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