Differences in Target Volume Delineation Using Typical Radiosurgery Planning System

Correct target volume delineation is an important part of radiosurgery treatment planning process. We designed head phantom and performed target delineation to evaluate the volume differences due to radiosurgery treatment planning systems and image acquisition system, CT/MR. Delineated mean target volume from CT scan images was 2.23±0.08 cm on BrainSCAN (NOVALS), 2.13±0.07 cm on Leksell gamma plan (Gamma Knife) and 2.24±0.10 cm on Multi plan (Cyber Knife). For MR images, 2.08±0.06 cm on BrainSCAN, 1.94±0.05 cm on Leksell gamma plan and 2.15±0.06 cm on Multi plan. As a result, Differences of delineated mean target volume due to radiotherapy planning system was 3% to 6%. And overall mean target volume from CT scan images was 6.36% larger than those of MR scan images. ????????????????????