Reduction of respiratory liver tumor motion by abdominal compression in stereotactic body frame, analyzed by tracking fiducial markers implanted in liver.
Wunderink W, Méndez Romero A, de Kruijf W, de Boer H, Levendag P, Heijmen B.
Abstract
PurposeTo investigate in a three-dimensional framework the effectiveness and reproducibility of reducing the respiratory motion of liver tumors using abdominal compression in a stereotactic body frame.Methods and materialsA total of 12 patients with liver tumors, who were treated with stereotactic body radiotherapy, were included in this study. These patients had three gold fiducial markers implanted in the healthy liver tissue surrounding the tumor. Fluoroscopic videos were acquired on the planning day and before each treatment fraction to visualize the motion of the fiducial markers during free breathing and varying levels of abdominal compression. Software was developed to track the fiducial markers and measure their excursions.ResultsAbdominal compression reduced the patient group median excursion by 62% in the craniocaudal and 38% in the anteroposterior direction with respect to the median free-breathing excursions. In the left-right direction, the median excursion increased 15% (maximal increase 1.6 mm). The median residual excursion was 4.1 mm in the craniocaudal, 2.4 mm in the anteroposterior, and 1.8 mm in the left-right direction. The mean excursions were reduced by compression to ConclusionsAbdominal compression effectively reduced liver tumor motion, yielding small and reproducible excursions in three dimensions. The compression level established at planning could have been safely used on the treatment days.