LAUSR

PurposeThe purpose of this study was to analyze the respiratory motion of each segment of the liver in patients with or without a history of abdominal surgery using four-dimensional computed tomography.Materials and methodsIn total, 57 patients treated for abdominal tumors using proton beam therapy were enrolled. Eighteen patients had a history of abdominal surgery and 39 did not. The positions of clearly demarcated, high-density regions in the liver were measured as evaluation points with which to quantify the motion of each liver segment according to the Couinaud classification.ResultsIn total, 218 evaluation points were analyzed. Comparison of differences in the motion of individual liver segments showed that among patients without a history of surgery, the maximum was 29.0 (7.2–42.1) mm in S6 and the minimum was 15.1 (10.6–19.3) mm in S4. Among patients with a history of surgery, the maximum was 28.0 (9.0–37.4) mm in S7 and the minimum was 6.3 (4.1–9.3) mm in S3.ConclusionThe distances and directions of respiratory motion differed for each liver segment, and a history of abdominal surgery reduced the respiratory motion of the liver. It is necessary to selectively use the internal margin setting.