A CsI(Na) based radiation detector for high resolution imaging studies using iodine 125 in small animal research

The authors report on the development of a high resolution radiation imaging system which is capable of detecting and imaging the coincident gamma and X-ray emissions of the radioisotope iodine 125 (125I). Iodine 125 is commonly available as a radioactive label to tag molecular biology probes. Iodine 125 decays via electron capture emitting a 35 keV gamma-ray with the prompt emission of several 27-32 keV X-rays. A coincidence condition can be set to detect the 125I decays thus reducing background radiation contribution to the image. They are testing the use of arrays of CsI(Na) crystal scintillators coupled to position sensitive photomultiplier tubes for this application. Laboratory studies have thus far been done on mice using a prototype of the detector which is intended to be used to image gene expression in live mice to advance research in neurobiology