The assignee ranking covers 100 companies, with the leader holding 114 of the 1,495 records in scope. Fifth place holds 55 records and tenth place holds 30, showing a gradual taper rather than a small clique holding everything. Together the top 5 assignees account for 26.2% of all records, and the top 10 account for 39.8%, leaving a substantial long tail of smaller filers.

Filing volume peaked at 166 records in 2021 and had fallen to 60 by 2024, a 64% decline over that span. That is the most reliable read available, because publication typically lags filing by roughly 18 months, so 2025 and 2026 figures in the dataset are still incomplete and should not be read as confirming or denying a continued slowdown. Based on complete years only, the field has cooled from its early-2020s peak.

While A61N (electrotherapy and radiation therapy) covers 69.9% of the 1,495 records, a meaningful share also touches A61B diagnosis and surgery (19.8%), G16H healthcare informatics (11.1%), G01T radiation measurement (7.2%) and G06F data processing (6.9%). Because records can carry multiple classes, these figures overlap rather than sum to 100%, and they show that planning-system patents increasingly cross into software and measurement territory alongside the core radiation-therapy hardware.

US8085899B2, assigned to Siemens Healthineers and granted in 2011, claims a treatment planning method that uses two dose calculation algorithms together — a complete, high-precision calculation and a faster, lower-precision incremental calculation used to speed up plan optimization. Anyone building a dual-precision or tiered dose-calculation workflow for speeding up optimization should review this claim scope closely, since it predates much of the field's current work on calculation-time reduction. It does not block single-algorithm dose engines or approaches that reduce calculation time through other means such as GPU parallelization or model simplification.

The comparatively thin sub-areas relative to the dominant A61N class include plan robustness under anatomical uncertainty, knowledge-based planning model transfer across treatment sites, Monte Carlo calculation-time reduction specific to particle therapy, automated objective-weighting for multi-criteria optimization, and commissioning workflow validation tools. These sit at the intersection of the smaller G16H and G06F classes and the core radiation-therapy claim space, which is where filing density is lower relative to the hardware-heavy majority of the dataset. A first claim in one of these areas should be checked against the existing knowledge-based planning and robustness literature already filed by the leading assignees before drafting.