Clinical Trial of Low-dose Radiation Therapy in Patients With Knee Osteoarthritis (LoRD-KNeA Trial)

Inclusion Criteria: * Age 50-85 years old * Kellgren-Lawrence grade 2-3 and diagnosed as a patient with primary knee osteoarthritis according to the ACR knee OA diagnostic criteria * Patients with VAS 40 or higher when walking, with or without medication at the time of screening * Patients who have VAS 50 or more and 90 or less when walking at the baseline * Among patients who were previously taking analgesic drugs at the time of screening, those with an increase in pain of 10 points or more at the baseline * Patients who do not want to take non-narcotic analgesics, those who have failed to control their pain due to the use of non-narcotic analgesics, or candidates for invasive treatment (intra-articular injection, arthroplasty, etc.) * A person who has a will to discontinue all pain medications except for rescue medications throughout screening, baseline, and clinical trials related to knee arthritis * A person who gives consent to use an approved contraceptive method from screening to 3 months after the end of the clinical trial * A person who understands the eligibility requirements for the study and has signed the consent form Exclusion Criteria: * A history of knee irradiation in the past * Patients participating in other degenerative arthritis clinical trials * Kellgren-Lawrence grade 4 * A history of malignancy within the last 5 years * A history of knee or hip surgery in the past * Patients who have received systemic steroid treatment or intra-articular steroid/hyaluronic acid injection within 2 months of screening * Patients with hip degenerative arthritis or other diseases of NRS 5 or higher that may affect functional score evaluation * Patients who are scheduled for surgical treatment of the knee joint during the clinical trial period * BMI \> 39 kg/m2 * Known history of analgesic or substance abuse within 2 years of screening * History, diagnostic signs or symptoms of any of the following clinically significant psychiatric disorders that would render the study ineligible (psychotic disorder, depression, somatic disorder) * History, diagnostic signs, or symptoms of any of the following clinically significant heart diseases that would render the study ineligible (surgery or stenting for ischemic heart disease and coronary artery disease within 6 months prior to screening) * History of other diseases that may affect the index joint, including autoimmune diseases (lupus, rheumatoid arthritis, etc.) * Fibromyalgia history or diagnosis * If the researcher judges that a person with significant trauma or other findings considered clinically important is inappropriate for participation in this study