The prevalence of chronic degenerative and inflammatory disorders, such as osteoarthritis, is constantly rising. As not all patients do respond adequately to the standard therapies, alternative treatment options such as low dose radiation therapy (LDRT) has gained further importance. LDRT is known to induce a long-lasting pain reduction, while having few side effects. Nonetheless, the detailed biological and immunological modes of action remain mostly elusive. In addition, there is a lack in placebo controlled randomised controlled trials (RCTs) proofing the pain-relieving effects of LDRT. So, the prospective, placebo-controlled, double-blind, randomized IMMO-LDRT02 trial to investigate the clinical efficacy of LDRT in the treatment of arthrosis should close this gap. Newly diagnosed or already existing arthroses of the fingers, wrists, shoulders, knees, ankles and feet will be enclosed. Finally, the evidence of clinical benefit from LDRT (6 x 0.5 Gy) will be compared to the placebo group (6 x 0 Gy), by determination via a visual analog scale (VAS) and identification of immunological changes, which contribute to the success of therapy and are specifically found in the test group (IMMO-LDRT01 trial; ClinicalTrials.gov Identifier: NCT02653079).