Abstract Purpose/objectives Collision avoidance is critical in external beam radiotherapy to ensure patient safety and plan deliverability. Limited understanding of the collision‐free treatment space risks both patient safety and unnecessary exclusion of useful beams—particularly in noncoplanar setups—resulting in suboptimal plans. Conventional methods (manual clearance checks or CT‐based assessments, etc.) are either labor‐intensive or fail to account for collision‐prone anatomy outside the scan. We investigated and clinically implemented a virtual patient‐specific clearance mapping system and evaluated its utility as a noncoplanar beam selection tool to improve plan quality. Materials/methods The system integrates full‐body, patient‐specific surfaces—acquired during simulation using near‐infrared imaging—with interactive 3D linac/couch models. Clearance mapping accuracy was validated through phantom measurements and a comparative analysis with manual clearance checks of 60 patients across treatment sites. Workflow efficiency data were reported over three years of clinical implementation. A workflow for patient‐specific non coplanar beam selection was proposed and evaluated in 20 lung stereotactic body radiation therapy (SBRT) and 18 breast stereotactic partial breast irradiation (sPBI) cases. Results The clearance mapping accuracy was within ± 1° (gantry/couch rotation) of phantom measurements. For 60 patients, the virtual predictions accurately identified all potential clearance issues, while manual verification missed 5 collision events. Virtual checks saved approximately 15 min of linac and therapist time per plan and eliminated an average 6.2‐clinical hour planning delay. With the proposed beam selection workflow, noncoplanar replans for lung SBRT improved target conformality (Paddick Conformity Index from 0.89 to 0.91, p < 0.01) and reduced low dose spillage. For breast sPBI, heart mean dose was lowered (103 cGy to 68 cGy, p < 0.01). Delivery time increased by approx. 30s per plan. Conclusions The virtual clearance mapping system outperformed manual verification, streamlined clinical workflow, and could significantly improve plan quality through efficient noncoplanar beam selection. It has replaced manual verification at our institution.
Wang et al. (Thu,) studied this question.
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