Interfractional variations in patient setup and anatomic change assessed by daily computed tomography.

Purpose: To analyze the interfractional variations in patient setup and anatomic changes at seven anatomic sites observed in image-guided radiotherapy.

Methods And Materials: A total of 152 patients treated at seven anatomic sites using a Hi-Art helical tomotherapy system were analyzed. Daily tomotherapy megavoltage computed tomography images acquired before each treatment were fused to the planning kilovoltage computed tomography images to determine the daily setup errors and organ motions and deformations.