Research On Key Technologies In Ultrasound Monitoring For Tumor Ablation

Tumor hyperthermia is a tumor treatment that heats tumor cells to kill them and protects normal cells. The thermal dose decides to the treatment effect, so noninvasive evaluation of treatment effect is important. Ultrasound, Magnetic Resonance Imaging and Computed Tomography are three main imaging methods which are available to monitor hyperthermia therapy. Ultrasound is widely used in in hyperthermia monitoring, because it is low cost, real-time, no radiation and ectromagnetic interference. The noninvasive monitoring ablation region using the raw backscattered data and automatic segmentation of breast ultrasound images are studied in this paper, and the ultrasonic monitoring system is designed. The main research refers to the following parts:1. An auto preliminary contour selection and an improved level set model help segment breast ultrasound imagesThe main purpose of this part of study is that using ultrasound image automatic segmentation technique determines tumor size accurately and helps doctors make preoperative assessment more conveniently, while this method can help doctors make operation plans. We use a method called speckle reducing anisotropic diffusion(SRAD) to deal with images to reduce speckle noise and to enhance features. In the preliminary contour selection, an efficient method helps detect the seed point. Then, region growing starts from the selected seed to obtain a preliminary contour that will serve as the intermediate result. Finally a novel and improved level set algorithm is proposed to confirm the final contour, combined with global statistics, local statistics, and region-based energy constraint. To increase the method's robustness and improve efficiency, some parameters are discussed, while the local statistics is calculated in the preliminary contour to reduce the time of this method.The proposed algorithm is tested on a database of 25 breast ultrasound images. Compared with the classic Chan-Vese model, the figures for the true positive rate and the similarity rise, while the proportions of the false positive rate and the error rate drop.2. Noninvasive ultrasound monitoring using Nakagami methodFirstly, we set up the experiment platform. The microwave heating experiment is designed and collects the raw backscattered data and B-mode images from the Ultrasound. After experiments, carve livers and measure ablation regions. Secondly, we use the Nakagami method to detect ablation region. This method helps analyze 18 ultrasound raw backscattered data, and results are compared with the ablation regions. The average deviation is 1.25%, which can mean that the accuracy rate of this method is high.3. Ultrasonic noninvasive monitoring system for microwave hyperthermia is designedUltrasonic noninvasive monitoring system for microwave hyperthermia is designed in Windows and MATLAB(R2012a), and this system can monitor ablation regions by analyze raw backscattered data. Main functions refer to the following parts: rebuilding ultrasound images, confirming ablation regions by using Nakagami method. doctors are able to observe the changes of tissues and the changes of coagulation zones.