一种快速电阻抗成像方法及其灵敏度研究

A Fast Reconstruction Method of Electrical Impedance Tomography and Its Sensitivity

该文介绍了一种基于等位线反投影算法的快速电阻抗断层成像方法,并实现了一种以等位线反投影算法为基础的实用动态电阻抗断层成像方法,分别研究了简单、复杂场域电导率分布下,该重建算法对场域内目标的定位精度及其对场域内部电导率分布变化的灵敏度。研究结果表明:该重建算法可以准确对目标进行定位,而且成像速度快,具有一定的分辨率,对场域内电导率分布的变化具有较好的灵敏度,但该重建算法的图像分辨率仍有待进一步提高。该快速电阻抗成像方法非常适合于对脑血肿、脑水肿患者的实时图像监护,以帮助医生及时做出正确的诊断,这在医学上有着重要的意义。

Electrical properties of tissues in the human body can be imaged using a technology known as Electrical Impedance Tomography (EIT). In this modality, sinusoidal electrical currents are applied to the body using electrodes attached to the skin, and voltages that are developed on the electrodes are measured. Using these data a reconstruction algorithm computes the electrical conductivity and permittivity distribution (or their changes) within the body. In this paper, a fast reconstruction method of Electrical Impedance Tomography is described in detail. The method has been established based on the method of back-projection along equipotential lines. It can obtain the changes of the electrical conductivity distribution in a cross-section of human body by measurements of electrodes' potentials on the skin surface. That is to say that the reconstructed image is a dynamic image (visualization of the difference between two measurements). The sensitivity of the method to the changes of the electrical conductivity distribution in the field is studied. The results show that the method based on equipotential back-projection algorithm can locate the object's (or several objects') position in the field with high precision, and its imaging speed is very fast. The changes of electrical conductivity distribution in the field can be precisely reflected from the reconstructed image. But the space resolution of the method must be improved in some extent. The fast reconstruction method based on the equipotential back-projection algorithm is very suitable for applying in the field of imaging monitoring for a patient with brain hematoma and brain edema. This is very significant to clinical medicine.