The Use of Low-Dose Radiation Therapy In Osteoarthritis: A Practical Joint-Specific Simulation and Planning Workflow
Abstract
Purpose
Low-dose radiation therapy (LDRT) is used in Europe for painful osteoarthritis (OA) and other inflammatory musculoskeletal conditions; however, U.S. adoption is limited in part by a lack of practical, reproducible simulation and planning guidance. We developed a joint-specific CT simulation and megavoltage photon planning template library to support consistent implementation of LDRT across small and large joints.
Methods
Joint-specific setup and planning templates were created for foot/toes, ankle, hand/wrist (prone and supine CT options plus clinical-simulation standing and stretcher options), knee, elbow, hip/shoulder, and spine. CT simulation emphasized reproducible positioning and immobilization, and superficial dose support with a 0.5-1.0 cm bolus placed anterior/posterior depending on geometry. MV photon energies were selected by site and depth (6 MV for small joints; 6-10 MV for larger or deeper joints). Beam arrangements were kept simple (AP/PA, opposed laterals, or single PA for spine). Nail beds were shielded with MLCs for hand/foot treatments when appropriate. Targeting encompassed the symptomatic joint and peri-articular tissues with 1.0-1.5 cm margins and a dose homogeneity goal of approximately +/-15%. Representative plans used 0.5 Gy x 6 fractions (3 Gy total) and were evaluated by target coverage (V100%) and maximum dose (Dmax).
Results
The protocol library provided a standardized workflow for seven anatomic regions and included alternative clinical-simulation pathways for patients unable to tolerate arms-over-head CT positioning, with measurement-based hand calculations and kV imaging for field verification. Across representative cases, V100% ranged 95%-99%. Dmax ranged 109%–115% across representative plans.
Conclusion
A practical CT simulation and MV planning template library for LDRT in OA was developed across small and large joints, including contingency workflows for limited mobility. Representative plans achieved hotspot levels consistent with a +15% homogeneity objective, providing a reproducible approach that may reduce barriers to safe and consistent clinical adoption of LDRT for benign inflammatory indications.