KEY POINTS
- OSTEO was developed specifically for low-dose RT in osteoarthritis, where conventional oncology plan-review tools do not fully address field-based joint treatment. The acronym covers Overdose, Size, Target coverage, Epicenter and Orientation.
- The framework recommends an ideal maximum point dose of ≤110% of prescription, with >120% considered unacceptable. For a standard prescription of 3 Gy in 6 fractions, the authors also recommend avoiding absolute hotspots above 1 Gy per fraction.
- Target coverage should ideally encompass the entire joint with the 95% isodose, while at minimum the whole joint should receive ≥90% of prescription. Major cold spots below 90% within the joint should prompt replanning.
- Each plan is scored across three domains — overdose, target coverage and field setup — from 0 to 3, yielding a total score of 0–9. A score of 0 in any domain indicates that the plan requires major revision.
- Validation included 21 clinically approved manual knee plans and 21 automated plans, independently reviewed by four radiation oncologists, producing 168 individual plan assessments.
- Inter-rater reliability was high for both manual plans (ICC 0.91) and automated plans (ICC 0.86). Mean total OSTEO scores were similar between the two planning approaches.
- All manual assessments scored acceptable or ideal in every domain, compared with 90% of automated assessments. No plan received a rejection score, so the ability of OSTEO to identify truly unacceptable plans remains untested.
CLINICAL TAKEAWAY
OSTEO gives clinicians a simple common language for reviewing osteoarthritis LDRT plans at a time when practice is expanding but planning conventions remain heterogeneous. It appears reproducible for knee plans, but the thresholds remain provisional QA criteria, not validated biological dose limits or evidence of treatment efficacy.