Study On Foggy Artifacts In B Scan Images Of HIFU Therapeutic System

In high intensity focused ultrasound (HIFU) therapeutic system, B-mode ultrasound imaging is applied in locating, monitoring and evaluating of curative effect in real-time. But foggy artifacts appearing in B scan images extensively cover the real image of the tissue and also affect the clinic application of HIFU therapeutic system. This paper analyzes its cause of forming, and sets up the mathematic model. The main characteristics of foggy artifacts are analyzed based on numeric simulation. According to the different characteristics between foggy artifacts and real tissue images, a differential method for foggy artifact suppression is proposed. The combination of the foggy artifact suppression scheme and the traditional scheme of HIFU therapy is also discussed.Based on the basic principle of B-mode ultrasound imaging, the different kinds of physical phenomenon, such as reflection, refraction, absorption, attenuation and so on, are discussed. The different kinds of traditional artifacts appearing in B scan images and artifacts suppression algorithms are summarized. And then foggy artifact existed in B scan images in HIFU therapeutic system is introduced in detail.By comparing the difference between the combined probe of HIFU therapeutic system and the single probe of general ultrasound diagnostic imaging system, the cause of forming of foggy artifact is analyzed: ultrasound pulses emitted by the B scan probe in the combined probe reflect and scatter at the skin surface, and then the foggy artifact is formed as a result of scattered echo's reflection back and forth between skin and smooth surface of the therapeutic probe in the combined probe. The mathematic model of foggy artifact is built up based on its physical mechanism. And the numerical simulation is also accomplished using MATLAB. The contrast between simulation results and real foggy artifacts in clinic B scan images indicates the validness of the genetic analysis and the mathematic model of foggy artifacts. The paper also further studies on the key factor affecting the forming of foggy artifacts, and the different characteristics between foggy artifacts and real tissue images.According to the different characteristics between foggy artifacts and real tissue images, a differential method for foggy artifacts suppression is proposed. In this scheme, the B scan image collected when the combined probe presses closely against skin is considered as the reference image. The differential result between B scan image...