Physics Posters PO76: A New Concept of a Mixed Reality-Guided Intraoperative Visual Support System for Combined Intracavitary and Interstitial Brachytherapy for Cervical Cancer

Purpose We developed a new concept of a mixed reality (MR)-guided intraoperative visual support system for inserting an interstitial needle applicator (needle) in combined intracavitary and interstitial brachytherapy (IC/IS-BT) for cervical cancer and evaluated its feasibility. Materials and Methods A CT image set of a cervical cancer patient who received IC/IS-BT was used as a demo case of this study. Treatment planning for the demo case was performed using the Oncentra BrachyR treatment planning system (Elekta, Inc., Stockholm, Sweden), and treatment plan data were stored as DICOM. These DICOM data were converted into STL data (represent three-dimensional [3D] shapes) and used as visual support data (3D models). MR-guided needle insertion is realized by importing these 3D models into the virtual world and mixing with the real world using a Head Mounted Display (HMD). In this study, Hololens 2 (Microsoft Corporation., Redmond, WA, USA) was chosen as an HMD and the Unity engine (Unity Software, Inc., San Francisco, CA, USA) and Microsoft Mixed Reality tool kit for Unity (MRTK-Unity) were used for the development of MR application. Results Using our developed concept and MR application, DICOM data were converted into STL and displayed 3D models on the HMD while maintaining these shapes and positions. The support data used in this study included CT and MRI images, structures of tumor and organs at risk, barycentric coordinates of the target, and dose distributions. These intraoperative visual support data are expected to reduce the risk of hemorrhage and intestinal puncture and shorten the procedure time. The surgeon's usability can be improved by switching display patterns (solid/transparent, wires, dots, etc.) and changing the combination of the projected support data. Conclusions A new concept of an MR-guided intraoperative visual support system was developed, and the feasibility of the system was suggested by the present study. We developed a new concept of a mixed reality (MR)-guided intraoperative visual support system for inserting an interstitial needle applicator (needle) in combined intracavitary and interstitial brachytherapy (IC/IS-BT) for cervical cancer and evaluated its feasibility. A CT image set of a cervical cancer patient who received IC/IS-BT was used as a demo case of this study. Treatment planning for the demo case was performed using the Oncentra BrachyR treatment planning system (Elekta, Inc., Stockholm, Sweden), and treatment plan data were stored as DICOM. These DICOM data were converted into STL data (represent three-dimensional [3D] shapes) and used as visual support data (3D models). MR-guided needle insertion is realized by importing these 3D models into the virtual world and mixing with the real world using a Head Mounted Display (HMD). In this study, Hololens 2 (Microsoft Corporation., Redmond, WA, USA) was chosen as an HMD and the Unity engine (Unity Software, Inc., San Francisco, CA, USA) and Microsoft Mixed Reality tool kit for Unity (MRTK-Unity) were used for the development of MR application. Using our developed concept and MR application, DICOM data were converted into STL and displayed 3D models on the HMD while maintaining these shapes and positions. The support data used in this study included CT and MRI images, structures of tumor and organs at risk, barycentric coordinates of the target, and dose distributions. These intraoperative visual support data are expected to reduce the risk of hemorrhage and intestinal puncture and shorten the procedure time. The surgeon's usability can be improved by switching display patterns (solid/transparent, wires, dots, etc.) and changing the combination of the projected support data. A new concept of an MR-guided intraoperative visual support system was developed, and the feasibility of the system was suggested by the present study.