数字减影过程中的灰度校正问题研究

Research on the Gray-Level Correction in Digital Subtraction Angiography

分析了直接数字减影法中不能完全消除与血管重叠的其他组织的影像问题 ,从理论和实验上提出了解决该问题的方法 .按照X线在人体组织中的吸收特点 ,建立了以“等效单能”模型为基础的X线成像模型 .在实际进行减影前 ,按照此关系对X线图像进行一定的灰度变换 ,减影结果就可以极大程度地消除血管以外的其他组织的影像 .实验结果证明了这种方法的有效性 .

When using direct subtraction in digital subtraction angiography, the shadow of another tissue which laps over the blood vessel cannot be eliminated completely. A method to solve this problem from theoretical and experimental aspects is presented. First, the imaging system is modeled based on 'equivalent single energy' of X-ray's absorbing characteristic in human tissue, and then the X-ray images are calibrated before digital subtraction angiography. After such processing, the subtracting result can remove the shadow greatly. Experimental results proved the validity of this method.