BETA-PARTICLE DOSIMETRY IN RADIATION SYNOVECTOMY

Beta-particle dosimetry of various radionuclides used in the treatment of rheumatoid arthritis was estimated using Monte Carlo radiation tra nsport simulation coupled with experiments using reactor-produced radi onuclides and radiachromic film dosimeters inserted into joint phantom s and the knees of cadavers. Results are presented as absorbed dose fa ctors (cGy-cm(2)/MBq-s) versus depth in a mathematical model of the rh eumatoid joint which includes regions of bone, articular cartilage, jo int capsule, and tissue (synovium) found in all synovial joints. The f actors can be used to estimate absorbed dose and dose rate distributio ns in treated joints. In particular, guidance is provided for those in terested in (a) a given radionuclide's therapeutic range, (b) the amou nt of radioactivity to administer on a case-by-case basis, (c) the exp ected therapeutic dose to synovium, and (d) the radiation dose imparte d to other, nontarget components in the joint, including bone and arti cular cartilage.