Automatic pelvic bone segmentation for radiotherapy using diagnostic imaging workstation

Background: This study evaluated the usefulness of a diagnostic imaging workstation in streamlining procedures and improving the accuracy of contouring pelvic bones with characteristic shapes. Materials and methods: The study included 18 patients with computed tomography (CT) images of the pelvic bone undergoing radiation therapy planning. Four pelvic bone structures (ST) were created: ST_EZ1, ST_EZ3, ST_Zio, and ST_MN. ST_EZ1 and ST_EZ3 using the automatic contouring function of EZ Sketch in Monaco (Elekta Inc.), a treatment planning system (TPS). ST_EZ3 was then duplicated and manually modified to create ST_MN. The CT data were reconstructed using Ziostation2 to create pelvic bone-only data, which were then imported into the TPS to create the structure using EZ Sketch. A 2-mm inner margin was added to create ST_Zio. Each structure was compared with ST_MN and evaluated using the Hausdorff distance (HD), mean distance to agreement (MDA), Dice similarity coefficient (DSC), and Jaccard similarity coefficient (JSC). Results: A comparison of ST_EZ1, ST_EZ3, and ST_Zio with ST_MN revealed the following: average HD, 53.87, 33.14, and 16.64, respectively; average MDA, 3.70, 2.03, and 0.99, respectively; average DSC, 0.80, 0.85, and 0.91, respectively; and average JSC, 0.68, 0.74, and 0.83, respectively. The average structure creation times were 1 min 7 s for ST_EZ1, 3 min 45 s for ST_EZ3, 1 min 50 s for ST_Zio, and 33 min 5 s for ST_MN. Conclusion: Diagnostic imaging workstations are effective for pelvic bone contouring, improving both efficiency and accuracy.