Author: Margaret Cunningham Barker, Michael E. Campbell, Peyman Kabolizadeh, A. Nisar Syed, Randy Wei, Lisa M. Wilson-Turner 👨🔬
Affiliation: Memorial Radiation Oncology Medical Group, MemorialCare Todd Cancer Institute 🌍
Purpose:
Interstitial HDR treatment planning can be time-consuming, with substantial time spent waiting for the patient’s arrival and performing manual tasks, such as contouring ROIs and catheter reconstruction in the TPS. A preliminary investigation was conducted to explore the use of the O-arm imager in the OR to create CT images for planning. The goal of this study is to evaluate the quality and ease of using O-arms for interstitial plans and determine whether pre-treatment imaging can assist in catheter and ROI reconstruction, thereby reducing staff time and workflow burden.
Methods:
The O-arm (Medtronic O-arm MVS O2) is a mobile CBCT scanner used in orthopedic, neuro-, and veterinary surgeries, providing accurate imaging of both bony and soft tissues. In the proposed workflow, after the implant procedure is completed in the OR, a volume image is captured by the technologist to verify needle placement. This image is then used as the starting point for the planning process. Once the patient is imaged on the department simulator, the O-arm image is registered, and the preliminary plan is adjusted accordingly.
Results:
The 3D displacement between the O-arm-based plan and the CT-sim plan was 0.76±1.6 cm (n=511 catheter dwell times). Catheter deflection increased, with a mean difference of 1.22±0.74° (n=42 catheters). For cases using the O-arm, the physics time required for planning increased by 1:22±0:33 (h:mm), compared to the standard workflow. Image quality was insufficient to clearly delineate OARs or catheter tips, which are crucial for accurate planning.
Conclusion:
Despite the promising nature of the O-arm integration, it did not improve the efficiency of the interstitial HDR workflow. Future revisions of the workflow will take place once an updated O-arm is installed, with protocol improvements aimed at better catheter visualization and soft tissue contrast for more effective planning.