Optical emission of (223) Radium: in vitro and in vivo preclinical applications

(223) Radium ((223) Ra) is widely used in Nuclear medicine to treat patients with osseous metastatic prostate cancer. In clinical practice (223) Ra cannot be imaged directly, however gamma photons produced by its short-lived daughter nuclides can be captured by conventional gamma cameras. In this work we show that (223) Ra and its short-lived daughter nuclides can be detected with optical imaging techniques. The light emission of (223) Ra was investigated in vitro using different setups in order to clarify the mechanism of light production. The results demonstrate that the luminescence of the (223) Ra chloride solution, usually employed in clinical treatments, is compatible with Cerenkov luminescence having an emission spectrum that is almost indistinguishable from Cerenkov radiation one. This study proves that luminescence imaging can be successfully employed to detect (223) Ra in vivo in mice by imaging whole body (223) Ra biodistribution and more precisely its uptake in bones.