陽子線治療における複数システム環境での複数室ダウンタイムイベントの管理：事例報告

To describe the management of a 5-day downtime event of a multi-room ProteusPLUS (P-PLUS) proton therapy (PT) system, including the triage and treatment of patients on a single-room ProteusONE (P-ONE) system and 2 linear accelerators.

Following the failure of a radiofrequency (RF) coupler, patients were triaged for PT on the P-ONE according to medical necessity and available capacity, aiming to minimize the complexity of the P-ONE workload while ensuring each patient received at least 4 fractions of radiotherapy that week. Replanning was required across non-beam matched systems (P-ONE, TrueBeam, and Synergy) and rapidly accomplished primarily via remote planning. Treatment adaptations included extending PT availability from 12 to 19 hours, the suspension of training of students and new therapists, the delay of new starts, and the use of kV oblique imaging for brain cases in lieu of cone-beam CT (CBCT).

A total of 42 patients were replanned within 30 hours, with an additional 5 patients replanned thereafter. The P-ONE averaged 60 patient treatments per day during the downtime event and achieved 61 treatments in 17.5 hours on a given day. Overall, 73% of scheduled PT fractions across all systems were treated with PT, with an additional 8% treated with photon therapy (XT), 13% postponed, and 6% canceled. All patients currently under treatment received at least 4 fractions of radiation therapy, with 73.6% receiving a full 5 fractions. The case mix on the P-ONE shifted towards less complex treatments overall (+13.4% prostate).

Swift triage, extended operating hours, and cross-platform re-planning enabled high-throughput and continuity of care during a significant downtime event. The event offers an early look at how downtime events can be successfully managed in a multi-system PT environment.