Hydroxyapatite (Ha) labeling with a phosphorus-32 radioisotope of the TRIGA 2000 reactor irradiation result as a candidate for radiosinovectomy therapy

Abstract

Radiosynovectomy is a therapy performed on patients with acute-level arthritis (rheumatoid arthritis) as an alternative solution besides surgery. Radiosynovectomy is performed using a labeled compound with a particle size of 0.5-10 μm labeled with a β radioisotope. Hydroxyapatite (HA) is a 1-10 μm-sized compound found in bones with the components of Calcium (Ca) & Phosphorus (P). Phosphorus-32 (32P) is a radioactive form of Phosphorus which emits pure beta rays and is often used for therapy. Labelling HA with 32P tends to be easy to do with a substitution reaction, because phosphorus is the main constituent of HA. Phosphorus-32 was made by irradiating natural sulfur at the Bandung TRIGA 2000 reactor facility following the 32S (n, p) 32P reaction mechanism. The separation process of Phosphorus-32 was carried out by a distillation method followed by extraction with 0.01 N HCl accompanied by heating for 30 minutes. The Phosphorus-32 solution is then passed through a 3 gr cation exchange resin. Before Phosphorus-32 was used for Labelling of HA, a Radionuclide Purity test was performed with a gamma-MCA spectrophotometer and a Radiochemical Purity test using paper chromatography. The test results showed Phosphorus-32 had Radionuclide Purity > 99.99% and Radiochemical Purity > 96%. 0.5 mCi Phosphorus-32 which meets the quality test requirements is reacted with 7 mg Ha at pH 7. Then it is vortexed at 1500 rpm for 60 minutes with 70 ° C heating. HA-32P is separated using centrifugation into residual and supernatant fractions. Measure the radioactivity of both fractions with a dose calibrator. Labeling Yield HA with Phosphorus-32 was obtained 98%. Furthermore this HA is ready to be used in in vivo tests for radiosynovectomy.