[en] The remarkable advances in the design and synthesis of radiopharmaceuticals has created the opportunity of generating new agents for the treatment of radiosynoviortheses (RSV) which exhibit a minimum leakage from the synovial joint reducing, this way, the non desired absorbed doses to non target organs such as liver, spleen, kidney. Nowadays, the variety of beta emitters used in RSV ranges between 0.34 MeV - 0.33 mm penetration in tissue (¹⁶⁹Er) and 2.27 MeV - 3.6 mm penetration in tissue (⁹⁰Y). The half life of these isotopes goes from 2.3 hours (¹⁶⁵Dy) to 27.8 days (⁵¹Cr). The selection criterion on which radionuclide should be used, in modern clinics, depends on which joints are to be treated. Thus, the smaller the joint, the lowest should be the energy of the beta emitted and the penetration in soft tissue of these particles. This leads to the use of fixed radionuclides and doses for each kind of joint. In the Isotopes Centre, we've been carrying on studies for the development of radiopharmaceuticals for the radiosynoviortheses treatment and focused our attention in the following radionuclides: ³²P, ⁹⁰Y, ¹⁸⁸Re, ¹⁷⁷Lu, ⁵¹Cr, ¹⁵³Sm and ¹⁶⁹Er. The main objective of this paper was to obtain the absorbed dose profiles for radionuclides of frequent or potential use in radiosynoviortheses. These profiles reveal the absorbed dose imparted per unit activity of injected radionuclide (Gy/h*MBq) in the synovial membrane and the articular cartilage. The researched radionuclides were those previously mentioned. Also were calculated the therapeutic range of each radionuclides in synovial tissue. The therapeutic range is defined as the deepness at which the absorbed dose equals the 10 % of the maximum dose deposited in the synovial surface. This range determines the synovial thickness that can be sufficiently irradiated and thus successfully treated. The synovial membrane model consisted on a cylinder with the source uniformly distributed in its volume. This model was simulated varying the radius of the cylinder (from 0.5 cm to 9 cm, with 0.5 cm increments) and its height (from 0.01 cm to 0.04 cm with 0.005 cm increments). The radii represent different sizes of the synovial surface (the area in the base of the cylinder) for small, medium and large joints. The height represents different stages of the progression of the rheumatoid arthritis (RA). The same model was employed for the simulation of the articular cartilage but, the source was uniformly distributed into a cylindrical slab (0.01 cm) and 1 cm of radio. The results obtained allow the estimation of the dose that will be delivered to the synovial membrane and the articular cartilage for different sizes of the joint and different stages of the disease. (author)