Stanford Completes Commissioning of First Gantry-Less Upright Proton Therapy System

The team at Stanford Radiation Oncology, in collaboration with Mevion Medical Systems and Leo Cancer Care, performed end-to-end testing of the Leo upright positioning platform integrated with a compact Mevion synchrocyclotron. Commissioning included beam modeling, patient-specific QA, and workflow validation across 50 simulated treatment fractions. Upright setups reduced gantry rotation needs and allowed real-time surface imaging for motion management.

This approach directly addresses access barriers in proton therapy, where traditional gantries cost $40-50 million and occupy large vaults. The compact design fits existing linac rooms, potentially cutting facility costs by half and allowing treatment of more patients per day. Related work at MGH and PSI has explored upright positioning for lung and head-neck cases, but this is the first full clinical commissioning report.

Key limitation is the absence of long-term patient outcome data; all metrics derive from phantom and commissioning measurements rather than a prospective trial. A multi-center study tracking local control and toxicity in the first 200 patients would strengthen evidence for routine adoption.

Next steps include FDA clearance and initiation of a phase II trial at Stanford targeting thoracic and pediatric indications within 18 months.