Applied Radiation and Isotopes 55 (2001) 471–475 Preparation and studies with 90 Y-labelled particles for use in radiation synovectomy Usha Pandey a , Atchana Mukherjee a , P.R. Chaudhary b , M.R.A. Pillai b , Meera Venkatesh a, * a Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai 400085, India b Radiation Medicine Centre, Bhabha Atomic Research Centre, Mumbai 400085, India Received 8 August 2000; received in revised form 22 January 2001; accepted 25 January 2001 Abstract 90 Y-FHMA (Ferric hydroxide macroaggregates) and 90 Y-HA (hydroxyapatite) were prepared in >95% yield using 90 Y from an in-house 90 Sr– 90 Y generator. Most of the particles ranged from 5 to 20 mm in diameter and retained radiochemical purity >95% in human serum for at least 7 days at 378C. Gamma camera imaging of normal rabbits after intraarticulation of the particles showed complete retention of activity within the knee cavity with no measurable radioactivity leaching out of the joints over a 96 hour period. # 2001 Elsevier Science Ltd. All rights reserved. 1. Introduction It is estimated that about 3% of the population worldwide (M . odder, 1995) is affected by rheumatoid arthritis which manifests mainly in the synovium. Because of the pain and debilitation, patients afflicted by this degenerative disease are grateful even for symptomatic relief without a permanent cure. The aim of radiation synovectomy is to reduce the pain, improve mobility and preserve joint function, resulting in better quality of life for the patient. Radiation synovectomy has been pursued for a number of years as an effective alternative to chemical and surgical synovectomy for treatment of arthritis (Zuckerman et al., 1987; Hosain et al., 1990; Deutsch et al., 1993; M . odder, 1995). Studies have shown the effectiveness of this procedure in controlling the symptoms of arthritis. Advances in this area have been facilitated by the availability of a wide range of beta emitting radionuclides and the feasibility of incorporating radionuclides into bio-degradable particles and colloids. Radiation synovectomy involves intraarticular injection at the synovial joint, of colloids or particles incorporating a b  emitting radionuclides. The inflamed synovium is ablated and the mechanism of action is believed to be the engulfment of particles by the macrophages present in large numbers, which then get irradiated and destroyed. Several radioisotopes such as 165 Dy, 199 Au, 32 P, 153 Sm, 166 Ho, 186/188 Re and 90 Y have been tested as potential nuclides for radiation synovect- omy in various forms (Hnatowich et al., 1977; Wang et al., 1995; Shortkroff et al., 1992). Identification of the radionuclide of choice and retention of the preparation within the joint cavity are the two main concerns for this procedure. Leakage of radioactivity from the joint will result in unnecessary and unacceptable radiation doses to non-target organs and usually results from either the very small size of the particles or the instability of the preparation leading to dissociation of the activity from the particles. The size distribution of the particles is of importance in this connection and particles between 5 and 20 mm diameter are believed to be ideally suited. Because of its favourable physical characteristics, 90 Y is used in radiation synovectomy, for treatment of rheumatoid arthritis particularly in Europe (Davis et al., 1989). It has a half-life of 64.1 h and decays to the stable 90 Zr daughter product, by emission of high energy b  radiation (E max =2.28MeV). The beta rays have a maximum tissue range of 11 mm which is useful for the *Corresponding author. Tel.: +91-22-5592449; fax: +91-22- 5505345. E-mail address: meerav@apsara.barc.ernet.in (M. Venkatesh). 0969-8043/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII:S0969-8043(01)00061-6