Study of different registration methods for on-line kilovoltage cone-beam CT guided lung cancer radiation

Abstract

Objective To select the optimal registration method for on-line kilovoltage cone-beam CT (KVCBCT) guided lung cancer radiation and evaluate the reproducibility of the selected method. MethodsSixteen patients with non-small cell lung cancer were enrolled into this study.A total of 96 pre treatment KVCBCT images from the 16 patients were available for the analysis.Image registration methods were bone-based automatic registration,gray-based automatic registration,manual registration and semi-auto matic registration.All registrations were accomplished by one physician.Another physician blindly evaluated the results of each registration,then selected the optimal registration method and evaluated its reproducibili ty.Results The average score of the bone-based automatic registration,gray-based automatic registration, manual registration and semi-automatic registration methods was 2.4,2.7,3.0 and 3.7,respectively.The score of the four different groups had statistics significant difference (F = 42.20,P < 0.001).Using the semi-automatic registration method,the probability of the difference between two registration results more than 3 ram in the left-right,superior-inferior,and anterior-posterior directions was 0,3% and 6% by the same physician,0,14% and 0 by different physicians,and 8%,14% and 8% by physician and radiation therapist.Conclusions Semi-automatic registration method,possessing the highest score and accepted re producibility,is appropriate for KVCBCT guided lung cancer radiation. Key words: Image-guided radiotherapy; Cone-beam CT; Image registration; Lung neoplasm