2Department of Radiotherapy, Acıbadem Mehmet Ali Aydınlar University, Vocational School of Health Services, İstanbul-Türkiye
3Department of Health Physics, İstanbul University, Institute of Oncology, İstanbul-Türkiye
4Department of Radiation Oncology, Üsküdar University Faculty of Medicine, İstanbul-Türkiye
5Department of Radiation Oncology, Biruni University Faculty of Medicine, İstanbul-Türkiye
6Department of Physics, İstanbul University Faculty of Science, İstanbul-Türkiye DOI : 10.5505/tjo.2025.4510 OBJECTIVE
The aim of this study was to evaluate the intra fractional tumor displacement by CBCT of patients with liver cancer who underwent stereotactic body radiotherapy in the presence of abdominal compression.
METHODS
Twenty patients with liver cancer, scheduled for stereotactic body radiotherapy, were included in the
study. An abdominal compression was applied to all patients to reduce tumor motion amplitude and
ensure repeatable tumor movement. To determine the extent of intra fractional tumor displacement
in the presence of abdominal compression, pre- and post-treatment CBCT images for all fractions
were evaluated.
RESULTS
The analysis of 3D-CBCT images taken before and after treatment revealed the following average
tumor position errors: 1.frx: 0.60±0.64 mm in the AP direction, 0.82±1.00 mm in the CC direction,
0.35±0.28 mm in the ML direction, and a total displacement vector (VT) of 1.29±0.98 mm. 2.frx:
0.21±0.24 mm in the AP direction, 0.47±0.62 mm in the CC direction, 0.26±0.32 mm in the ML direction,
and a VT of 0.68±0.64 mm. 3.frx: 0.15±0.30 mm in the AP direction, 0.37±0.48 mm in the CC
direction, 0.74±1.91 mm in the ML direction, and a VT of 1.04±1.89 mm.
CONCLUSION
Respiratory-related liver motion can lead to the creation of a large ITV for liver tumors, and therefore
this effect should be reduced by appropriate immobilization techniques. Abdominal compression is a
quite effective equipment to prevent intra-fractional position errors by limiting the movement of intraabdominal
organs. This study demonstrated that when the abdominal compression method is used, the
intra fractional motion of liver tumors remains within the 5 mm PTV margin.