Alpha emitter radiation

Radium Ra 223 (223Ra) emits alpha particles (i.e., two protons and two neutrons bound together, identical to a helium nucleus) with a half-life of 11.4 days. It is administered intravenously and selectively taken up by newly formed bone stroma. The high-energy alpha particles have a short range of less than 100 mcM. 223Ra improved OS in patients with prostate cancer metastatic to bone. In a double-blind, randomized, controlled trial, 921 men with symptomatic castration-resistant prostate cancer, two or more metastases, and no known visceral metastases were randomly assigned in a 2:1 ratio to 223Ra versus placebo. 223Ra statistically significantly improved OS (median 14.9 months vs. 11.3 months), rate of symptomatic skeletal events (33% vs. 38%), and spinal cord compression (4% vs. 7%).[81,82][Level of evidence A1] With administration at a dose of 50kBq per kg body weight every 4 weeks for six injections, the side effects were similar to those of a placebo.