Main Session
Sep
30
PQA 08 - Gastrointestinal Cancer, Nonmalignant Disease, Palliative Care
3409 - CT-Based Target Delineation and Low-Dose Radiotherapy for Knee Osteoarthritis - A Single Center Experience
Presenter(s)
Yu-Hsuan Chuang, MD - Far Eastern Memorial Hospital, New Taipei City, Taiwan
Y. H. Chuang1, Y. F. Lu1, P. W. Shueng2, C. X. Hsu1, D. Y. Kuo1, P. Hou1, and C. H. Hsieh1; 1Division of Radiation Oncology, Department of Radiology, Far Eastern Memorial Hospital, New Taipei City 220, Taiwan, 2School of Medicine, College of Medicine, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
Purpose/Objective(s):
Low-dose radiotherapy (LDRT) has been a noninvasive and cost-effective treatment used to reduce pain and improve joint function in osteoarthritis (OA). Previous literature showed 60-90% pain relief in irradiated patients. However, standardized guidelines for target delineation remain limited, particularly for modern RT techniques. This study aimed to evaluate the feasibility and safety of LDRT using a soft tissue anatomy-based clinical target volume (CTV) in patients with symptomatic knee OA.Materials/Methods:
We retrospectively analyzed patients with symptomatic knee OA (Kellgren–Lawrence grade 1–4) at our institution who were treated with linear accelerators using the VMAT technique from August 2024 to January 2025. We defined the CTV based on simulation CT to encompass the entire knee joint, including the articular cavity and synovial membrane, while sparing the adjacent muscles. A 1 cm setup margin was then added to create the planning target volume (PTV). Patients received a total of 3 Gy in 6 fractions (0.5 Gy per fraction, administered on non-consecutive days). Orthogonal kV imaging was performed prior to treatment to confirm accurate setup. We collected pain measurements (on a 10-point visual analog scale [VAS]) before and 2 weeks after treatment completion. Toxicity was defined as any adverse events occurring during this interval, graded according to CTCAE v5.0.Results:
We retrospectively analyzed patients with symptomatic knee OA (Kellgren–Lawrence grade 1–4) at our institution who were treated with linear accelerators using the VMAT technique from August 2024 to January 2025. We defined the CTV based on simulation CT to encompass the entire knee joint, including the articular cavity and synovial membrane, while sparing the adjacent muscles. A 1 cm setup margin was then added to create the planning target volume (PTV). Patients received a total of 3 Gy in 6 fractions (0.5 Gy per fraction, administered on non-consecutive days). Orthogonal kV imaging was performed prior to treatment to confirm accurate setup. We collected pain measurements (on a 10-point visual analog scale [VAS]) before and 2 weeks after treatment completion. Toxicity was defined as any adverse events occurring during this interval, graded according to CTCAE v5.0. Mild, transient erythema (Grade 1) was seen in 1 patient, with spontaneous recovery. Another patient reported slight hyperesthesia, which resolved within a week.Conclusion:
Our experience supports the application of LDRT with a soft tissue anatomy-based target delineation in treating symptomatic knee OA patients. Standardization of anatomy-based contouring may further enhance reproducibility and treatment precision. Larger prospective studies with extended follow-up are needed to validate our results and assess long-term safety and efficacy.