DEVELOPMENT OF A NOVEL RADIATION IMAGING DETECTOR SYSTEM FOR IN-VIVO GENE IMAGING IN SMALL ANIMAL STUDIES

We report preliminary results from a prototype of radiation imaging te chnology which takes advantage of the emission properties of the radio isotope iodine 125 (I-125) as the probe, The detector system utilizes crystal scintillators and a position sensitive photomultiplier tube. I odine 125 decays via electron capture emitting a 35-keV gamma ray with the prompt emission of several 27-32-keV K alpha and K beta shell X r ays. Because of this, a coincidence condition can be set to detect the I-125 decay, thus reducing background radiation contribution to the i mage. The prototype detector we report has a limited sensitivity and d etection area because of the size of the scintillators and photomultip lier tubes, Set it performed well enough to demonstrate the viability of this method for imaging I-125 in a mouse, Mouse imaging studies of iodine uptake by the thyroid and melatonin binding have been done with this detector system using doses of I-125 alone or attached to the me latonin, Many studies in molecular biology follow the expression and r egulation of a gene at different stages of an organism's development o r under different physiological conditions. Molecular biology research could benefit from this detection system by utilizing I-125-labeled g ene probes.