토모다이렉트 3D-CRT을 이용한 유방암 환자의 회전 오차

Abstract

The purpose of this study was to analyze the rotational errors of roll, pitch, and yaw in the whole breast cancertreated by the three-dimensional radiation therapy (3D-CRT) using TomoDirect (TD). Twenty-patient previouslytreated with TD 3D-CRT was selected. We performed a retrospective clinical analysis based on 80 images ofmegavoltage computed tomography (MVCT) including the systematic and random variation with patient setuperrors and treatment setup margin (mm). In addition, a rotational error (degree) for each patient was analyzedusing the automatic image registration. The treatment margin of X, Y, and Z directions were 4.2 mm, 6.2 mm,and 6.4 mm, respectively. The mean value of the rotational error for roll, pitch, and yaw were 0.3°, 0.5°, 0.1°,and all of systematic and random error was within 1.0°. The errors of patient positioning with the Y and Z directionshave generally been mainly higher than the X direction. The percentage in treatment fractions in less than 2°at roll, pitch, and yaw are 95.1%, 98.8%, and 97.5%, respectively. However, the edge of upper and lower (i.e.,bottom) based on the center of therapy region (point) will quite a possibility that it is expected to twist evenlonger as the length of treatment region. The patient-specific characters should be considered for the accuracyand reproducibility of treatment and it is necessary to confirm periodically the rotational errors, including patientrepositioning and repeating MVCT scan.