Labeling, such as with radio pharmaceuticals, fluorescence emitting compounds or other probe detectable materials, of diseased or malfunctioning candidate cells for subsequent treatment with a medicinal compound, the identification in situ of the candidate cells using a probe sensitive to the presence of the label and then treatment of the identified cell is disclosed.The invention also covers in situ gene therapy using a beta or gamma radiation detection probe to locate radio-labeled cells, and the delivery of corrective or therapeutic genes to the candidate cells identified by the radiation detection probe while the probe is positioned adjacent to the labeled and located cells. Also covered is the identification of vulnerable plaque in atherosclerotic vessels and diseased myocardial tissue in the heart, treatment of that plaque or diseased tissue and the subsequent determination of the efficacy of the treatment.Devices for use in the procedures include, intraoperative radiation detection probes, intraoperative radiation detection probes, intraoperative radiation imaging probes, catheter mounted radiation detection probes and probes attached to surgical gloves so that the probe tip can be manually manipulated by the physician and placed adjacent to suspect tissue at an operative site.