Research On Ultrasonic Temperature Imaging Artifact Elimination Method Based On Single Phase CBE

Radiofrequency Ablation(RFA)is the most commonly used minimally invasive surgery to remove liver tumors.It releases energy through the ablation needle inserted into the tumor to achieve local necrosis of the tissue.In this process,the ablation temperature needs to be monitored to prevent the temperature from being too high and the surrounding tissue or the temperature is too low to completely ablate the tumor.Ultrasonic is safe and easy to implement.It not only provides real-time feedback of the electrode position during radiofrequency ablation,but also displays temperature information in the tissue.Changes in Backscattered Energy(CBE)is an ultrasonic temperature imaging method widely used to evaluate thermal ablation.However,in the study,there will be obvious artifacts in temperature images that seriously affect the correct distribution of the ablation area due to bubbles and electrodes using traditional CBE method.This thesis proposes an ultrasonic single-phase CBE imaging method based on positive CBE value.After filtering and encapsulating the original data,the positive CBE value is extracted to replace the bi-phase CBE value of the traditional CBE method for sliding window and interpolation processing to suppresses artifacts under the ablation needle.The validation experiment used pork tenderloin as a tissue sample,and 15 sets of ablation needle lengths of 0.5 cm,1 cm,and 1.5 cm were performed at 50 W power.Ultrasound of tissue samples was performed using a clinical ultrasound scanner equipped with a 3 MHz convex array transducer.Scanning through the transducer to obtain image raw data consisting of 256 backscattered ultrasound signal scan lines for B-mode imaging,traditional CBE and single-phase CBE imaging.Comparing the results of two CBE imaging methods and perform polynomial fitting to calculate the ablation area Correlation coefficient.The experimental results show that single-phase CBE imaging can suppress the artifacts under ablation needle in the traditional CBE imaging in the temperature range from 20 °C to 100 °C,and obtain a more accurate temperature distribution image.In addition,single-phase CBE imaging provides an improved estimate of RF ablation area(correlation coefficient higher than 0.8),thus establishing a unified method for temperature monitoring and ablation area estimation in RF ablation procedures,providing a new idea in clinical application for CBE imaging.