Optimizing Safe and Efficient Lung Biopsy Trajectories Using Voxel-Based Straight-Line Path Planning
Abstract
Purpose
To develop and evaluate a voxel-based straight-line trajectory planning framework for CT-guided lung biopsy that enables safe and efficient pre-procedural identification of needle paths while minimizing risk to organs at risk (OARs).
Methods
A voxel-level trajectory planning framework was implemented using a high-resolution three-dimensional XCAT digital phantom (567 × 567 × 567 voxels) with labeled anatomical structures, including skin, fat, muscle, lung, and implanted tumors. To ensure conservative safety modeling, all remaining labeled tissues were treated as OARs. Candidate straight-line trajectories were generated by uniformly sampling radial directions from the tumor center across spherical angles (θ, φ). Each trajectory was voxel-traced outward to the skin surface and rejected if it intersected any OAR voxel or violated a clinically motivated 3-mm OAR clearance margin defined using a distance transform. Additional constraints excluded trajectories with clinically unfavorable insertion angles. To address potential needle overshoot during lung biopsy, post-target path segments beyond the tumor were evaluated, and trajectories aligned with OARs immediately downstream of the tumor were excluded. Feasible trajectories were ranked by total path length, and the shortest candidates were retained for visualization and analysis.
Results
The proposed framework consistently generated multiple clinically feasible lung biopsy trajectories that satisfied safety, angular, and post-target clearance constraints while maintaining minimal path length. Rather than producing a single globally shortest trajectory, the method identified and ranked multiple shortest feasible paths, enabling clinician-in-the-loop selection of safe alternatives based on procedural considerations. Voxel-level evaluation enabled rapid and systematic assessment of anatomical feasibility, trajectory risk, and spatial orientation within a standard patient coordinate system.
Conclusion
This safety-aware straight-line planning approach provides an efficient and interpretable solution for patient-specific lung biopsy trajectory optimization. The method establishes a practical baseline for decision support and future extensions to curved-path planning, respiratory motion compensation, and robotic image-guided biopsy systems.