Activity leakage and radiation exposure in radiation synovectomy of the knee: influence of different therapeutic modalities

In rheumatic diseases, radiation synovectomy is a reliable method. Meanwhil e, radiation synovectomy is an outpatient therapy. In addition, combination with arthroscopic synovectomy is an in creasing therapeutic modality. In c omparison to the hitherto inpatient modality, a greater lymphatic emigratio n of the radionuclide and, therefore, a higher radiation exposure is possib le. In 35 patients we found radionuclide emigration in 17 cases by whole bo dy scintigraphy, resulting in a 50%-percentile with 68.27%-confidence inter val of 1.8 (0.45-4.78)% of the injected yttrium-90-activity. Comparison of 3 groups with the above mentioned therapy modalitites resulted in no statis tical difference (p>0.05). Because of the found radionuclide emigration, a radiation dose of 0.1 (0.05-0,18) mSv in women and 0.2 (0.1-0.38) mSv in me n was calculated. For lymph nodes, liver, spleen and whole body radiation d oses of 619 (154-1644) mSv, 62 (15-165) mSv, 62 (15-165) mSv and 37 (9-99) mSv were calculated. Gonadal radiation dose can be neglected and the morbid ity rate for tumors bacause of the whole body radiation dose is low with a value of 0.4 per thousand. Therefore, radiation synovectomy can be used unl imited by patients age and independent of the therapeutic modality.