Rhenium Re-186 is radioisotope of rhenium. It is produced in many nuclear reactors throughout the world, and the 90-hour half-life can often permit distribution to sites distant from the production facilities. Re-186 decays with emission of beta-particles which have a range of up to 4.5 mm in tissues. Rhenium-186 complex with 1-hydroxy-ethylidene-1,1 diphosphonic acid (HEDP) is used for palliative treatment of bone metastases originating from breast or prostate cancer. Re-186-labeled sulfur colloid particles are used for the therapy of rheumatoid arthritis of the synovial joints.