SU‐E‐J‐133: The Comparison of Modified Demons Algorithm and FFD Algorithm Based On B‐Spline and Analysis of Morphology of Normal Liver and Tumor by Breathing Motion

Abstract

Purpose: Through comparing the modified demons algorithm and FFD algorithm based on B‐spline, and combing four‐dimensional computed tomography (4D‐CT), we discussed the morphology of normal liver and tumor by breathing motion of hepatocellular carcinoma patients. Methods: 8 hepatocellular carcinoma (HCC) patients accepted radiotherapy and TACE was selected, the simulate positioning was in four‐dimensional computed tomography (4D‐CT) pattern and 4D‐CT images were segmented into 10‐series CT images which were named CT0, CT10 to CT80, CT90 according to the respiratory phases. We used the modified demons algorithm and FFD algorithm based on B‐spline respectively to deform the images, and the end‐exhale image CT50 was the reference image. The normalized mutual information (NMI), hausdorff distance (NMI) and time consuming were used to verify the performance of the registration methods. Results: The average NMI for the end‐inhale and end‐exhale images of 8 HCC patients after demons registration method in mode 1 improved 1.76% comparing with that in mode 2 and 4.75% improving than FFD algorithm. And the difference of after demons method reduced 15.2% comparing with FFD model algorithm. In addition, demons algorithm has the absolute advantage in time consuming. Conclusion: The breathing movement for deformation of normal liver and tumor targets is significant, and the modified demons registration method can deform 4D‐CT images effectively.