SU-E-P-21: To Investigate CT and KV CBCT Image Deformable Contour Registration Method Using Lung Phantom

Abstract

Purpose: To analyze CT and KV CBCT image deformable contour registration method and explore calibration CBCT image quality method to achive the goal of Adaptive Radiotherapy(ART) using lung phantom Methods: Acquiring CT, CBCT and modified CBCT (mCBCT) images(calibtated by electron density and image quality) of the anthropomorphic lung phantom. The body contour, simulated targets volume (a sphere with diameter 3.0 centimeters located on left lung, mediastinum and right lung) and simulated organ at risks(OARs) on CT image were deformed to CBCT and mCBCT images with Mimivista software. We achieved the auto deformable conntours and compared with manual contours. We anlyzed the DSC(dice similarity coefficient), PPV(positive predictive value) and SENS(sensitivity) of the body, targets and OARs for three images. Results: Compared to auto contours on CBCT, auto contours on mCBCT had a higher value of 0.7% Dice index and a higher value of 2.51% PPV for body; a higher DSC of 32.50%,a higher PPV of 21.30% and a higher of SENS 30.39% for simulation PTV;a higher DSC of 17.35% and a higher SENS of 32.82% for heart. There were no difference for other parameters of simulation organs. Conclusion: KV CBCT images callibtated by electron density and image quality with the anthropomorphic lung phantom have a good deformable registration contours compared to CBCT auto contours without calibration.